android6.0源码分析之Runtime的初始化

Android运行时作为android架构的一部分，起着非常重要的作用，它和核心库(Core Libraries)组成了Android运行时库层。本文将依据android源码对AndroidRuntime(android运行时)的建立过程进行分析。

1、Android架构中的AndroidRuntime

android采用的是层次化系统架构，它的架构图如下： 


 

由架构图可知，AndroidRuntime处于Linux内核层以及应用框架层中间，而Java的运行环境依赖于Java虚拟机，所以AndroidRuntime对于android系统非常重要。Init进程是Linux环境下非常重要的一个进程，而Zygote进程是Java环境下的第一个进程，所有其他的Java环境下的进程都是由Zygote进程来进行fork的，而init进程在启动Zygote进程之后，初始化Zygote进程之前，会先进行AndroidRuntime的启动和环境建立，下文将对此过程进行详细分析。

2、init进程分析

init进程作为linux启动过程中的一个重要的进程，它主要负责文件系统的挂载，属性的初始化，各种配置的加载启动以及Action触发，Service的启动，而Zygote作为Java环境下的服务进程，也在Init.rc中进行了配置，而init进程是由main函数进行触发的，其main函数如下：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//Init.cpp
int main(int argc, char **argv){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//清除umask默认属性
umask();
add_environment(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"PATH"</span>,_PATH_DEFPATH);
//判断是不是初始化的第一阶段
bool is_first_stage = (arg == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)||(strcmp(argv[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>],<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"--second-stage"</span>)!=<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(is_first_stage){
//进行系统文件系统等的挂载
mount(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"tmpfs"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/dev"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"tmpfs"</span>,MS_NOSUID,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"mode=0755"</span>);
mkdir(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/dev/pts"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0755</span>);
mkdir(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/dev/socket"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0755</span>);
mount(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"devpts"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/dev/pts"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"devpts"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>);
mount(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"proc"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/proc"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"proc"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>);
mount(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"sysfs"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/sys"</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"sysfs"</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>,<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>);
}
open_devull_stdio();
//klog初始化
klog_init();
klog_set_level(KLOG_NOTICE_LEVEL);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(!is_first_stage){
//关闭/dev/.booting文件的相关权限
close(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"/dev/.booting"</span>,O_WRONLY|O_WCREAT|O_CLOEXEC,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">000</span>);
//初始化部分属性
property_init();
//先初始化DT，因为DT的属性集的优先级高于comand line
process_kernel_dt();
//处理内核命令行
process_kernel_cmdline;
//导出内核变量
export_kernel_boot_props();
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//初始化信号量
signal_handler_init();

property_load_boot_defaults();
//开启属性服务
start_property_service();

//解析/init.rc文件
init_parse_config_file(/init.rc);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li></ul>

此处的代码与android 4.4等，在代码上有略微的差别，但是基本的操作还是一样的，首先进行一些属性的初始化，内核命令行等以及信号量的初始化，最后再启动属性服务以及对init.rc文件进行解析，所以，接下来分析Init.rc文件：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//Init<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>
import /init<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.environ</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>
import /init<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.usb</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>
import /init.${ro<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.hardware</span>}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>
import /init.${ro<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.zygote</span>}<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>
import /init<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.trace</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.rc</span>
...</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

由代码可知，与android4.4等有明显的差别，此处采用导入.rc文件的方式来初始化相应模块，此处分析zygote模块，对于android6.0来说，它提供了多个zygote相关的.rc文件，有Init.zygote32.rc、Init.zygote32_64.rc、Init.zygote64.rc、Init.zygote64_32.rc等，本文分析Init.zygote32.rc，其他流程是一样的，但是在源码中，只发现了Init.zygote32.rc的相关实现。 

看Init.zygote32.rc文件：

<code class="hljs livecodeserver has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//Init.zygote32.rc
service zygote /<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">system</span>/bin/app_process -Xzygote /<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">system</span>/bin <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">--zygote --start-system-server</span>
class main
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">socket</span> zygote stream <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">660</span> root <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">system</span>
onrestart <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">write</span> /sys/android_power/request_state wake
onrestart <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">write</span> /sys/power/state <span class="hljs-command" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">on</span></span>
onrestart restart media
onrestart restart netd</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>

由代码可知，它将会执行/system/bin/app_process，而后面的是它的参数，请注意–zygote和–start-system-server参数，后面将会分析到，而对于/system/bin/app_process的实现app_main.cpp(frameworks/base/cmds/app_process)，它的配置在frameworks/base/cmds/app_process目录下的Android.mk文件中：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//Android.mk(frameworks/base/cmds/app_process)
LOCAL_PATH = $(call my-dir)
app_process_common-shared_libs:=\
libwilhelm\
include $(CLEAR_VARS)
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">#看，app_process命令绑定的源码就是该目录下的app_main.cpp</span>
LOCAL_SRC_FILES:=\
app_main.cpp
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

所以，app_process命令绑定的源码实现就是app_main.cpp，在解析Init.zygote32.rc文件的时候，会调用到它的main函数，即app_main.cpp的main函数。

3、Android运行时的启动分析

上一节分析了Init进程启动与android运行时的关系，因为对于android运行时的启动来说，它是在Init进程之后，zygote进程启动之后，初始化之前初始化的，所以此时它的入口和zygote的入口一致，即app_main.cpp的main函数，代码如下：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//app_main.cpp
int main(int argc, char* const argv[]){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//AppRuntime继承自AndroidRuntime
AppRuntime runtime(argv[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>], computeArgBlockSize(argc, argv));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (zygote) {//如果init.rc配置中有--Zygote，参数为com.android.internal.os.ZygoteInit
runtime.start(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"com.android.internal.os.ZygoteInit"</span>, args);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (className) {//否则参数为com.android.internal.os.RuntimeInit
runtime.start(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"com.android.internal.os.RuntimeInit"</span>, args);
}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>{
//显示命令的用法说明
app_usage();
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>

首先创建一个AppRuntime对象，接着调用它的start方法，而此start方法在父类AndroidRuntime中进行了定义，并且此处的参数为com.android.internal.os.ZygoteInit，而对于两种不同的参数而言，只是最后启动的类不一样，如果有–zygote参数，其最后会启动ZygoteInit类，否则就会执行RuntimeInit类，继续追踪start方法。

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//AndroidRuntime.cpp
void AndroidRuntime::start(const char* className, const Vector<String8>& options){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//启动虚拟机
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (startVm(&mJavaVM, &env) != <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span>;
}
//模板方法模式，只是为了创建VM之后释放slashClassName的内存
onVmCreated(env);
//注册Android JNI函数
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (startReg(env) < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
ALOGE(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Unable to register all android natives\n"</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span>;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//解析类名
char* slashClassName = toSlashClassName(className);
//找到需要启动的java类
jclass startClass = env->FindClass(slashClassName);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (startClass == <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>) {
ALOGE(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JavaVM unable to locate class '%s'\n"</span>, slashClassName);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
//得到指定类中指定方法的ID，这里得到的是RuntimeInit.main()的方法ID
jmethodID startMeth = env->GetStaticMethodID(startClass, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"main"</span>,
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"([Ljava/lang/String;)V"</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (startMeth == <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>) {
ALOGE(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JavaVM unable to find main() in '%s'\n"</span>, className);
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> {
//调用上面得到的方法ID和相关参数，即调用Java类ZygoteInit.main();
env->CallStaticVoidMethod(startClass, startMeth, strArray);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li></ul>

首先分析Java虚拟机的启动：由以上代码可知，在start方法中，调用startVm()方法进行虚拟机的启动，startVm()的具体代码如下：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//AndroidRuntime.cpp
int AndroidRuntime::startVm(JavaVM** pJavaVM, JNIEnv** pEnv, bool zygote){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//读取第一个参数指定的属性操作到buffer，并设置默认的参数
parseRuntimeOption(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"dalvik.vm.stack-trace-file"</span>, stackTraceFileBuf,
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"-Xstacktracefile:"</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//添加相应的handler操作
addOption(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"exit"</span>, (void*) runtime_exit);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//读取作为dex2oat compiler运行时操作
parseCompilerOption(dex2oat_isa_variant_key, dex2oat_isa_variant,
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"--instruction-set-variant="</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"-Xcompiler-option"</span>);
// 拷贝特性
sprintf(dex2oat_isa_features_key, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"dalvik.vm.isa.%s.features"</span>, instruction_set);
parseCompilerOption(dex2oat_isa_features_key, dex2oat_isa_features,
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"--instruction-set-features="</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"-Ximage-compiler-option"</span>);
parseCompilerOption(dex2oat_isa_features_key, dex2oat_isa_features,
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"--instruction-set-features="</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"-Xcompiler-option"</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//初始化虚拟机
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (JNI_CreateJavaVM(pJavaVM, pEnv, &initArgs) < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
ALOGE(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JNI_CreateJavaVM failed\n"</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li></ul>

由代码可知：首先进行一系列的属性读取到buffer的操作，如JIT相关的options,DexClassLoader的相关options等，并将其添加到操作数组容器里面，最后再调用JNI_CreateJavaVM方法进行VM的创建,如果此调用发挥成功的话，那么我们就能够济宁JNI调用了，继续看此方法的代码，它的定义出现在DdmConnection的start方法里：

<code class="hljs cpp has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//DdmConnection.cpp</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> DdmConnection::start(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">const</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">char</span>* name) {
...
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//定义JNI_CreateJavaVM方法</span>
jint (*JNI_CreateJavaVM)(JavaVM** p_vm, JNIEnv** p_env, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>* vm_args);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//从libart_dso库中解析JNI_CreateJavaVM方法</span>
JNI_CreateJavaVM = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">reinterpret_cast</span><<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">decltype</span>(JNI_CreateJavaVM)>(
dlsym(libart_dso, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JNI_CreateJavaVM"</span>));
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//定义registerNatives方法</span>
jint (*registerNatives)(JNIEnv* env, jclass clazz);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//从libandroid_runtime_dso库中解析registerNatives方法</span>
registerNatives = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">reinterpret_cast</span><<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">decltype</span>(registerNatives)>(
dlsym(libandroid_runtime_dso,
<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"Java_com_android_internal_util_WithFramework_registerNatives"</span>));

...
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li></ul>

JNI_CreateJavaVM方法是从libart_dso库中解析得到的，同样后面要用到的registerNatives方法从事libandroid_runtime_dso库中解析得到的，而这两个库也是在DdmConnection的start方法中打开的，代码如下：

<code class="hljs cs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>* libart_dso = dlopen(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"libart.so"</span>, RTLD_NOW);
ALOGE_IF(!libart_dso, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"DdmConnection: %s"</span>, dlerror());
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>* libandroid_runtime_dso = dlopen(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"libandroid_runtime.so"</span>, RTLD_NOW);
ALOGE_IF(!libandroid_runtime_dso, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"DdmConnection: %s"</span>, dlerror());</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

而当JNI_CreateJavaVM函数执行成功后，当前本地线程已经把自己的控制权交给JVM，而具体的JNI_CreateJavaVM方法的实现在libart_dso库中，此处不做深究。至此，成功创建了Java虚拟机，而startVm方法也分析结束。

接着分析onVmCreated方法，它使用的是模板方法的设计模式，在androidRuntime中声明并使用，而具体的实现在appRuntime子类中进行，其代码如下：

<code class="hljs lasso has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">virtual <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">void</span> onVmCreated(JNIEnv<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">*</span> env){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(mClassName<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">.</span>isEmpty()){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span>;<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//Zygote.Nothing to do here</span>
}
char<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">*</span> slashClassName <span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=</span> toSlashClassName(mClassName<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">.</span><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">string</span>());
mClass <span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=</span> env<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">-></span>FndClass(slashClassName);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(mClass <span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">==</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NULL</span>){
ALOGE(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ERROR:could not find class '%s'\n"</span>,mClassName<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">.</span><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">string</span>);
}
free(slashClassName);
mClass <span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=</span> reinterpret<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;"><</span>jclass<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">></span>(env<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">-></span>NewGlobalRef(mClass));
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

只是简单根据类名获取了类，并释放了类名，所以此处不做过多的分析，接下来分析startReg()方法，方法定义代码如下：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">/*static*/ int AndroidRuntime::startReg(JNIEnv* env)
/*
* This hook causes all future threads created <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> this process to be
* attached to the JavaVM.  (This needs to go away <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> favor of JNI
* Attach calls.)
*/
androidSetCreateThreadFunc((android_create_thread_fn) javaCreateThreadEtc);

ALOGV(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"--- registering native functions ---\n"</span>);

/*
* Every <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"register"</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span> calls one or more things that <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span>
* a local reference (e.g. FindClass).  Because we haven<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'t really
* started the VM yet, they'</span>re all getting stored <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">in</span> the base frame
* and never released.  Use Push/Pop to manage the storage.
*/
env->PushLocalFrame(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">200</span>);

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (register_jni_procs(gRegJNI, NELEM(gRegJNI), env) < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) {
env->PopLocalFrame(<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> -<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;
}
env->PopLocalFrame(<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">NULL</span>);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li></ul>

startReg方法主要的作用是进行android JNI函数的注册，从代码可知：它调用函数register_jni_procs()方法将gRegJNI中的方法注册到虚拟机，而gRegJNI中的Native方法如下：

<code class="hljs autohotkey has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">static const RegJNIRec gRegJNI[] = {
REG_JNI(register_com_android_internal_os_RuntimeInit),
REG_JNI(register_android_os_SystemClock),
REG_JNI(register_android_util_EventLog),
REG_JNI(register_android_util_Log),
REG_JNI(register_android_content_AssetManager),
REG_JNI(register_android_content_StringBlock),
REG_JNI(register_android_content_XmlBlock),
REG_JNI(register_android_emoji_EmojiFactory),
REG_JNI(register_android_text_AndroidCharacter),
REG_JNI(register_android_text_StaticLayout),
REG_JNI(register_android_text_AndroidBidi),
REG_JNI(register_android_view_InputDevice),
REG_JNI(register_android_view_KeyCharacterMap),
REG_JNI(register_android_os_Process),
REG_JNI(register_android_os_SystemProperties),
REG_JNI(register_android_os_Binder),
REG_JNI(register_android_os_Parcel),
REG_JNI(register_android_nio_utils),
REG_JNI(register_android_graphics_Graphics),
REG_JNI(register_android_view_DisplayEventReceiver),
REG_JNI(register_android_view_RenderNode),
REG_JNI(register_android_view_RenderNodeAnimator),
REG_JNI(register_android_view_GraphicBuffer),
REG_JNI(register_android_view_DisplayListCanvas),
REG_JNI(register_android_view_HardwareLayer),
REG_JNI(register_android_view_ThreadedRenderer),
REG_JNI(register_android_view_Surface),
REG_JNI(register_android_view_SurfaceControl),
REG_JNI(register_android_view_SurfaceSession),
REG_JNI(register_android_view_TextureView),
REG_JNI(register_com_android_internal_view_animation_NativeInterpolatorFactoryHelper),
REG_JNI(register_com_google_android_gles_jni_EGLImpl),
REG_JNI(register_com_google_android_gles_jni_GLImpl),
REG_JNI(register_android_opengl_jni_EGL14),
REG_JNI(register_android_opengl_jni_EGLExt),
REG_JNI(register_android_opengl_jni_GLES10),
REG_JNI(register_android_opengl_jni_GLES10Ext),
REG_JNI(register_android_opengl_jni_GLES11),
REG_JNI(register_android_opengl_jni_GLES11Ext),
REG_JNI(register_android_opengl_jni_GLES20),
REG_JNI(register_android_opengl_jni_GLES30),
REG_JNI(register_android_opengl_jni_GLES31),
REG_JNI(register_android_opengl_jni_GLES31Ext),

REG_JNI(register_android_graphics_Bitmap),
REG_JNI(register_android_graphics_BitmapFactory),
REG_JNI(register_android_graphics_BitmapRegionDecoder),
REG_JNI(register_android_graphics_Camera),
REG_JNI(register_android_graphics_CreateJavaOutputStreamAdaptor),
REG_JNI(register_android_graphics_Canvas),
REG_JNI(register_android_graphics_CanvasProperty),
REG_JNI(register_android_graphics_ColorFilter),
REG_JNI(register_android_graphics_DrawFilter),
REG_JNI(register_android_graphics_FontFamily),
REG_JNI(register_android_graphics_Interpolator),
REG_JNI(register_android_graphics_LayerRasterizer),
REG_JNI(register_android_graphics_MaskFilter),
REG_JNI(register_android_graphics_Matrix),
REG_JNI(register_android_graphics_Movie),
REG_JNI(register_android_graphics_NinePatch),
REG_JNI(register_android_graphics_Paint),
REG_JNI(register_android_graphics_Path),
REG_JNI(register_android_graphics_PathMeasure),
REG_JNI(register_android_graphics_PathEffect),
REG_JNI(register_android_graphics_Picture),
REG_JNI(register_android_graphics_PorterDuff),
REG_JNI(register_android_graphics_Rasterizer),
REG_JNI(register_android_graphics_Region),
REG_JNI(register_android_graphics_Shader),
REG_JNI(register_android_graphics_SurfaceTexture),
REG_JNI(register_android_graphics_Typeface),
REG_JNI(register_android_graphics_Xfermode),
REG_JNI(register_android_graphics_YuvImage),
REG_JNI(register_android_graphics_pdf_PdfDocument),
REG_JNI(register_android_graphics_pdf_PdfEditor),
REG_JNI(register_android_graphics_pdf_PdfRenderer),

REG_JNI(register_android_database_CursorWindow),
REG_JNI(register_android_database_SQLiteConnection),
REG_JNI(register_android_database_SQLiteGlobal),
REG_JNI(register_android_database_SQLiteDebug),
REG_JNI(register_android_os_Debug),
REG_JNI(register_android_os_FileObserver),
REG_JNI(register_android_os_MessageQueue),
REG_JNI(register_android_os_SELinux),
REG_JNI(register_android_os_Trace),
REG_JNI(register_android_os_UEventObserver),
REG_JNI(register_android_net_LocalSocketImpl),
REG_JNI(register_android_net_NetworkUtils),
REG_JNI(register_android_net_TrafficStats),
REG_JNI(register_android_os_MemoryFile),
REG_JNI(register_com_android_internal_os_Zygote),
REG_JNI(register_com_android_internal_util_VirtualRefBasePtr),
REG_JNI(register_android_hardware_Camera),
REG_JNI(register_android_hardware_camera2_CameraMetadata),
REG_JNI(register_android_hardware_camera2_legacy_LegacyCameraDevice),
REG_JNI(register_android_hardware_camera2_legacy_PerfMeasurement),
REG_JNI(register_android_hardware_camera2_DngCreator),
REG_JNI(register_android_hardware_Radio),
REG_JNI(register_android_hardware_SensorManager),
REG_JNI(register_android_hardware_SerialPort),
REG_JNI(register_android_hardware_SoundTrigger),
REG_JNI(register_android_hardware_UsbDevice),
REG_JNI(register_android_hardware_UsbDeviceConnection),
REG_JNI(register_android_hardware_UsbRequest),
REG_JNI(register_android_hardware_location_ActivityRecognitionHardware),
REG_JNI(register_android_medi<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">a_AudioRecord</span>),
REG_JNI(register_android_medi<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">a_AudioSystem</span>),
REG_JNI(register_android_medi<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">a_AudioTrack</span>),
REG_JNI(register_android_medi<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">a_JetPlayer</span>),
REG_JNI(register_android_medi<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">a_RemoteDisplay</span>),
REG_JNI(register_android_medi<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">a_ToneGenerator</span>),

REG_JNI(register_android_opengl_classes),
REG_JNI(register_android_server_NetworkManagementSocketTagger),
REG_JNI(register_android_ddm_DdmHandleNativeHeap),
REG_JNI(register_android_backup_BackupDataInput),
REG_JNI(register_android_backup_BackupDataOutput),
REG_JNI(register_android_backup_FileBackupHelperBase),
REG_JNI(register_android_backup_BackupHelperDispatcher),
REG_JNI(register_android_app_backup_FullBackup),
REG_JNI(register_android_app_ActivityThread),
REG_JNI(register_android_app_NativeActivity),
REG_JNI(register_android_view_InputChannel),
REG_JNI(register_android_view_InputEventReceiver),
REG_JNI(register_android_view_InputEventSender),
REG_JNI(register_android_view_InputQueue),
REG_JNI(register_android_view_KeyEvent),
REG_JNI(register_android_view_MotionEvent),
REG_JNI(register_android_view_PointerIcon),
REG_JNI(register_android_view_VelocityTracker),

REG_JNI(register_android_content_res_ObbScanner),
REG_JNI(register_android_content_res_Configuration),

REG_JNI(register_android_animation_PropertyValuesHolder),
REG_JNI(register_com_android_internal_content_NativeLibraryHelper),
REG_JNI(register_com_android_internal_net_NetworkStatsFactory),
}<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li><li style="box-sizing: border-box; padding: 0px 5px;">111</li><li style="box-sizing: border-box; padding: 0px 5px;">112</li><li style="box-sizing: border-box; padding: 0px 5px;">113</li><li style="box-sizing: border-box; padding: 0px 5px;">114</li><li style="box-sizing: border-box; padding: 0px 5px;">115</li><li style="box-sizing: border-box; padding: 0px 5px;">116</li><li style="box-sizing: border-box; padding: 0px 5px;">117</li><li style="box-sizing: border-box; padding: 0px 5px;">118</li><li style="box-sizing: border-box; padding: 0px 5px;">119</li><li style="box-sizing: border-box; padding: 0px 5px;">120</li><li style="box-sizing: border-box; padding: 0px 5px;">121</li><li style="box-sizing: border-box; padding: 0px 5px;">122</li><li style="box-sizing: border-box; padding: 0px 5px;">123</li><li style="box-sizing: border-box; padding: 0px 5px;">124</li><li style="box-sizing: border-box; padding: 0px 5px;">125</li><li style="box-sizing: border-box; padding: 0px 5px;">126</li><li style="box-sizing: border-box; padding: 0px 5px;">127</li><li style="box-sizing: border-box; padding: 0px 5px;">128</li><li style="box-sizing: border-box; padding: 0px 5px;">129</li><li style="box-sizing: border-box; padding: 0px 5px;">130</li><li style="box-sizing: border-box; padding: 0px 5px;">131</li><li style="box-sizing: border-box; padding: 0px 5px;">132</li><li style="box-sizing: border-box; padding: 0px 5px;">133</li><li style="box-sizing: border-box; padding: 0px 5px;">134</li><li style="box-sizing: border-box; padding: 0px 5px;">135</li><li style="box-sizing: border-box; padding: 0px 5px;">136</li><li style="box-sizing: border-box; padding: 0px 5px;">137</li><li style="box-sizing: border-box; padding: 0px 5px;">138</li><li style="box-sizing: border-box; padding: 0px 5px;">139</li><li style="box-sizing: border-box; padding: 0px 5px;">140</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li><li style="box-sizing: border-box; padding: 0px 5px;">64</li><li style="box-sizing: border-box; padding: 0px 5px;">65</li><li style="box-sizing: border-box; padding: 0px 5px;">66</li><li style="box-sizing: border-box; padding: 0px 5px;">67</li><li style="box-sizing: border-box; padding: 0px 5px;">68</li><li style="box-sizing: border-box; padding: 0px 5px;">69</li><li style="box-sizing: border-box; padding: 0px 5px;">70</li><li style="box-sizing: border-box; padding: 0px 5px;">71</li><li style="box-sizing: border-box; padding: 0px 5px;">72</li><li style="box-sizing: border-box; padding: 0px 5px;">73</li><li style="box-sizing: border-box; padding: 0px 5px;">74</li><li style="box-sizing: border-box; padding: 0px 5px;">75</li><li style="box-sizing: border-box; padding: 0px 5px;">76</li><li style="box-sizing: border-box; padding: 0px 5px;">77</li><li style="box-sizing: border-box; padding: 0px 5px;">78</li><li style="box-sizing: border-box; padding: 0px 5px;">79</li><li style="box-sizing: border-box; padding: 0px 5px;">80</li><li style="box-sizing: border-box; padding: 0px 5px;">81</li><li style="box-sizing: border-box; padding: 0px 5px;">82</li><li style="box-sizing: border-box; padding: 0px 5px;">83</li><li style="box-sizing: border-box; padding: 0px 5px;">84</li><li style="box-sizing: border-box; padding: 0px 5px;">85</li><li style="box-sizing: border-box; padding: 0px 5px;">86</li><li style="box-sizing: border-box; padding: 0px 5px;">87</li><li style="box-sizing: border-box; padding: 0px 5px;">88</li><li style="box-sizing: border-box; padding: 0px 5px;">89</li><li style="box-sizing: border-box; padding: 0px 5px;">90</li><li style="box-sizing: border-box; padding: 0px 5px;">91</li><li style="box-sizing: border-box; padding: 0px 5px;">92</li><li style="box-sizing: border-box; padding: 0px 5px;">93</li><li style="box-sizing: border-box; padding: 0px 5px;">94</li><li style="box-sizing: border-box; padding: 0px 5px;">95</li><li style="box-sizing: border-box; padding: 0px 5px;">96</li><li style="box-sizing: border-box; padding: 0px 5px;">97</li><li style="box-sizing: border-box; padding: 0px 5px;">98</li><li style="box-sizing: border-box; padding: 0px 5px;">99</li><li style="box-sizing: border-box; padding: 0px 5px;">100</li><li style="box-sizing: border-box; padding: 0px 5px;">101</li><li style="box-sizing: border-box; padding: 0px 5px;">102</li><li style="box-sizing: border-box; padding: 0px 5px;">103</li><li style="box-sizing: border-box; padding: 0px 5px;">104</li><li style="box-sizing: border-box; padding: 0px 5px;">105</li><li style="box-sizing: border-box; padding: 0px 5px;">106</li><li style="box-sizing: border-box; padding: 0px 5px;">107</li><li style="box-sizing: border-box; padding: 0px 5px;">108</li><li style="box-sizing: border-box; padding: 0px 5px;">109</li><li style="box-sizing: border-box; padding: 0px 5px;">110</li><li style="box-sizing: border-box; padding: 0px 5px;">111</li><li style="box-sizing: border-box; padding: 0px 5px;">112</li><li style="box-sizing: border-box; padding: 0px 5px;">113</li><li style="box-sizing: border-box; padding: 0px 5px;">114</li><li style="box-sizing: border-box; padding: 0px 5px;">115</li><li style="box-sizing: border-box; padding: 0px 5px;">116</li><li style="box-sizing: border-box; padding: 0px 5px;">117</li><li style="box-sizing: border-box; padding: 0px 5px;">118</li><li style="box-sizing: border-box; padding: 0px 5px;">119</li><li style="box-sizing: border-box; padding: 0px 5px;">120</li><li style="box-sizing: border-box; padding: 0px 5px;">121</li><li style="box-sizing: border-box; padding: 0px 5px;">122</li><li style="box-sizing: border-box; padding: 0px 5px;">123</li><li style="box-sizing: border-box; padding: 0px 5px;">124</li><li style="box-sizing: border-box; padding: 0px 5px;">125</li><li style="box-sizing: border-box; padding: 0px 5px;">126</li><li style="box-sizing: border-box; padding: 0px 5px;">127</li><li style="box-sizing: border-box; padding: 0px 5px;">128</li><li style="box-sizing: border-box; padding: 0px 5px;">129</li><li style="box-sizing: border-box; padding: 0px 5px;">130</li><li style="box-sizing: border-box; padding: 0px 5px;">131</li><li style="box-sizing: border-box; padding: 0px 5px;">132</li><li style="box-sizing: border-box; padding: 0px 5px;">133</li><li style="box-sizing: border-box; padding: 0px 5px;">134</li><li style="box-sizing: border-box; padding: 0px 5px;">135</li><li style="box-sizing: border-box; padding: 0px 5px;">136</li><li style="box-sizing: border-box; padding: 0px 5px;">137</li><li style="box-sizing: border-box; padding: 0px 5px;">138</li><li style="box-sizing: border-box; padding: 0px 5px;">139</li><li style="box-sizing: border-box; padding: 0px 5px;">140</li></ul>

由上可知，在系统建立androidRuntime的时候，创建Java虚拟机，并将系统中一些JNI函数注册到Java虚拟机中，此后只需要通过JNI的方法就可以调用这些Native方法，此外JNI函数的注册还有一种方法，即通过静态代码块System.LoadLibrary(“…”);来加载自定义的JNI方法。至此，其实Runtime已经初始化完成了。，其时序图如下： 

4、非zygote模式的RuntimeInit分析

非zygote模式下，app_process命令行的输入参数没有了–zygote等，所以className变成了com.android.internal.os.RuntimeInit，但是前面的流程还是差不多，只是在AndroidRuntime的start方法中的最后有代码：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//AndroidRuntime.cpp
void AndroidRuntime::start(const char* className, const Vector<String8>& options){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
//调用上面得到的方法ID和相关参数，这里调用的是RuntimeInit.main();
env->CallStaticVoidMethod(startClass, startMeth, strArray);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

它会根据输入的参数com.android.internal.os.ZygoteInit和RuntimeInit，通过反射以及JNI，找到相应的类，并调用类的main方法，本文是在Init进程中来进行Runtime的初始化并启动Zygote进程(Java域的第一个进程)的，它的启动分析请参考我的文章android6.0源码分析之Zygote进程分析，另外，系统提供app_process的命令，我们可以利用此命令来实现很多供我们自己开发、测试、定制一些特殊的程序，给开发带来了很大的便利。所以，接下来继续分析非zygote模式下的RuntimeInit，首先分析RuntimeInit类的main方法：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//RuntimeInit.java
public static final void main(String[] argv){
//看到没有，Ddms使能，我们调试时要用到的
enaleDdms();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span>(argv.length == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>&&argv[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>].equals(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"application"</span>)){
//设置系统输出System.out和System.err的Log Stream
redirectLogStreams();
}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>{}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
commonInit();
nativeFinishInit();
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

commonInit方法主要就是初始化VM里的线程的默认Handler，初始化Log Manager以及一些属性的初始化等，接着看nativeFinishInit方法:

<code class="hljs scss has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//AndroidRuntime.cpp</span>
<span class="hljs-value" style="box-sizing: border-box;">static</span> void <span class="hljs-function" style="box-sizing: border-box;">com_android_internal_os_RuntimeInit_nativeFinishInit(JNIEnv* env,jobject clazz)</span>{
gCurRuntime-><span class="hljs-function" style="box-sizing: border-box;">onStarted()</span>;
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

onStarted方法的实现在app_main.cpp的AppRuntime类中：

<code class="hljs lasso has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//app_main.cpp</span>
virtual <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">void</span> onStarted(){
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//在进程中开启线程池</span>
sp<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;"><</span>ProcessState<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">></span> proc <span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=</span> ProcessState<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;">::self</span>();
proc<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">-></span>startThreadPool();
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取运行时对象</span>
AndroidRuntime<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">*</span> ar <span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">=</span> AndroidRuntime<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;">::getRuntime</span>();
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//调用mClassName的main方法</span>
ar<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">-></span>callMain(mClassName,mClass,mArgs);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//停止线程池</span>
IPCThreadState<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;">::self</span>()<span class="hljs-subst" style="color: rgb(0, 0, 0); box-sizing: border-box;">-></span>stopProcess();
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li></ul>

其中最主要的就是callMain的调用：

<code class="hljs r has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">//AndroidRuntime
status_t AndroidRuntime::callMain(const String8& className,jclass clazz,const Vector<String8>&
args){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
env = getJNIEnv();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">...</span>
env.CallStaticVoidMethod(clazz,methodId,strArray);
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> NO_ERROR;
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>

最后，在进行相应的RuntimeInit初始化后，会执行命令中相应测试应用（或命令）的main方法。其时序图如下： 



原文地址：http://blog.csdn.net/yangzhihuiguming/article/details/51697801