阿里巴巴FastJson---高性能JSON开发包

声明：本文内容来源于http://blog.csdn.net/glarystar/article/details/6654494,为了便于查阅故复制到个人博客

Fastjson介绍

Fastjson是一个Java语言编写的JSON处理器,由阿里巴巴公司开发。

1、遵循http://json.org标准，为其官方网站收录的参考实现之一。

2、功能强大，支持JDK的各种类型，包括基本的JavaBean、Collection、Map、Date、Enum、泛型。

3、无依赖，不需要例外额外的jar，能够直接跑在JDK上。

4、开源，使用Apache License 2.0协议开源。http://code.alibabatech.com/wiki/display/FastJSON/Home
5、具有超高的性能，java世界里没有其他的json库能够和fastjson可相比了。

如果获得Fastjson？

SVN:http://code.alibabatech.com/svn/fastjson/trunk/

WIKI:http://code.alibabatech.com/wiki/display/FastJSON/Home

Issue Tracking:http://code.alibabatech.com/jira/browse/FASTJSON

如果你使用了Maven，maven repository配置如下：

<span style="font-size:13px"><repository>
<id>opensesame</id>
<name>Alibaba OpenSource Repsoitory</name>
<url>http:</span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">//code.alibabatech.com/mvn/releases/</url>
</span></span><span style="font-size:13px">	<snapshots>
<enabled></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">false</span></span><span style="font-size:13px"></enabled>
</snapshots>
</repository>
</span>

pom.xml文件中加入依赖依赖：

<span style="font-size:13px"><dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.0.4</version>
</dependency>
</span>

如果没有使用maven，可以直接下载：

Binary : http://code.alibabatech.com/mvn/releases/com/alibaba/fastjson/1.1.1/fastjson-1.1.1.jar

Source :http://code.alibabatech.com/mvn/releases/com/alibaba/fastjson/1.1.1/fastjson-1.1.1-sources.jar

Subversion : http://code.alibabatech.com/svn/fastjson/

使用介绍：

Fastjson的最主要的使用入口是com.alibaba.fastjson.JSON

<span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">import</span></span><span style="font-size:13px"> com.alibaba.fastjson.JSON;

</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Object</span></span><span style="font-size:13px"> parse(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> text); </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">// 把JSON文本parse为JSONObject或者JSONArray
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> JSONObject parseObject(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> text)； </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">// 把JSON文本parse成JSONObject
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> <T> T parseObject(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> text, </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Class</span></span><span style="font-size:13px"><T> clazz); </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">// 把JSON文本parse为JavaBean
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> JSONArray parseArray(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> text); </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">// 把JSON文本parse成JSONArray
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> <T> List<T> parseArray(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> text, </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Class</span></span><span style="font-size:13px"><T> clazz); </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">//把JSON文本parse成JavaBean集合
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> toJSONString(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Object</span></span><span style="font-size:13px"> object); </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">// 将JavaBean序列化为JSON文本
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> toJSONString(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Object</span></span><span style="font-size:13px"> object, </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">boolean</span></span><span style="font-size:13px"> prettyFormat); </span><span class="code-comment" style="color:#808080;background-color:inherit"><span style="font-size:13px">// 将JavaBean序列化为带格式的JSON文本
</span></span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">static</span></span><span style="font-size:13px"> </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">final</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Object</span></span><span style="font-size:13px"> toJSON(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Object</span></span><span style="font-size:13px"> javaObject); 将JavaBean转换为JSONObject或者JSONArray。
</span>

代码示例：

代码示例用到类User和Group：

<span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> class User {
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">private</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Long</span></span><span style="font-size:13px"> id;
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">private</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> name;

</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Long</span></span><span style="font-size:13px"> getId() { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">return</span></span><span style="font-size:13px"> id; }
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> void setId(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Long</span></span><span style="font-size:13px"> id) { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">this</span></span><span style="font-size:13px">.id = id; }

</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> getName() { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">return</span></span><span style="font-size:13px"> name; }
</span><span class="cod
1612e
e-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> void setName(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> name) { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">this</span></span><span style="font-size:13px">.name = name; }
}
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> class Group {
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">private</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Long</span></span><span style="font-size:13px"> id;
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">private</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> name;
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">private</span></span><span style="font-size:13px"> List<User> users = </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">new</span></span><span style="font-size:13px"> ArrayList<User>();

</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Long</span></span><span style="font-size:13px"> getId() { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">return</span></span><span style="font-size:13px"> id; }
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> void setId(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">Long</span></span><span style="font-size:13px"> id) { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">this</span></span><span style="font-size:13px">.id = id; }

</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> </span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> getName() { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">return</span></span><span style="font-size:13px"> name; }
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> void setName(</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> name) { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">this</span></span><span style="font-size:13px">.name = name; }

</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> List<User> getUsers() { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">return</span></span><span style="font-size:13px"> users; }
</span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">public</span></span><span style="font-size:13px"> void setUsers(List<User> users) { </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">this</span></span><span style="font-size:13px">.users = users; }
}
</span>

Encode代码示例：

<span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">import</span></span><span style="font-size:13px"> com.alibaba.fastjson.JSON;

Group group = </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">new</span></span><span style="font-size:13px"> Group();
group.setId(0L);
group.setName(</span><span class="code-quote" style="color:#0910;background-color:inherit"><span style="font-size:13px">"admin"</span></span><span style="font-size:13px">);

User guestUser = </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">new</span></span><span style="font-size:13px"> User();
guestUser.setId(2L);
guestUser.setName(</span><span class="code-quote" style="color:#0910;background-color:inherit"><span style="font-size:13px">"guest"</span></span><span style="font-size:13px">);

User rootUser = </span><span class="code-keyword" style="color:#0091;background-color:inherit"><span style="font-size:13px">new</span></span><span style="font-size:13px"> User();
rootUser.setId(3L);
rootUser.setName(</span><span class="code-quote" style="color:#0910;background-color:inherit"><span style="font-size:13px">"root"</span></span><span style="font-size:13px">);

group.getUsers().add(guestUser);
group.getUsers().add(rootUser);

</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">String</span></span><span style="font-size:13px"> jsonString = JSON.toJSONString(group);

</span><span class="code-object" style="color:#91091;background-color:inherit"><span style="font-size:13px">System</span></span><span style="font-size:13px">.out.println(jsonString);
</span>

Decode 代码示例：

<span style="font-size:13px">Group group2 = JSON.parseObject(jsonString, Group.class);
</span>

之前的一个版本是1.1.0，1.1.0采用asm和SortFastMatch算法提高性能，由于过于着急展示其优越的性能，没有进行严格测试就发布了。

1.1.1相对于1.1.0，这是一个比较稳定的版本了，行测试覆盖率重新提升到90%以上，build verify testcase 983个。

这个版本进一步完善了asm和SortFieldFastMatch算法，进一步提升了性能，同时补充了大量的testcase，提升了稳定性，我向你推荐使用这个版本，使用这个版本你将会得到令人惊奇的性能。

1.1.1版本的asm来源自objectweb的asm项目，根据fastjson的需要做裁剪，确保引入asm的同时不引起包大小的过渡变大。

为了更好使用sort field martch优化算法提升parser的性能，fastjson序列化的时候，缺省把SerializerFeature.SortField特性打开了。反序列化的时候也缺省把SortFeidFastMatch的选项打开了。这样，如果你用fastjson序列化的文本，输出的结果是按照fieldName排序输出的，parser时也能利用这个顺序进行优化读取。这种情况下，parser能够获得非常好的性能。

我使用github.com/eishay/jvm-serializers/提供的程序做测试，性能数据如下：

	序列化时间	反序列化时间	大小	压缩后大小
java序列化	8546	43199	889	541
hessian	6643	10043	501	313
protobuf	3008	1694	239	149
thrift	3182	1951	349	197
avro	3575	2095	221	133
json-lib	45734	149741	485	263
jackson	3245	2986	503	271
fastjson	2292	1499	468	251

测试跑的脚本是：

<span style="font-size:13px">./run -chart -include=`cat serializers.txt | tr </span><span class="code-quote" style="color:#0910;background-color:inherit"><span style="font-size:13px">"\\n"</span></span><span style="font-size:13px"> </span><span class="code-quote" style="color:#0910;background-color:inherit"><span style="font-size:13px">","</span></span><span style="font-size:13px">`  data/media.1.cks
</span>

从上面的数据来看，fastjson的性能已经超越protobuf、thrift、avro这些二进制协议了。一个文本协议的性能超越二进制协议是很难的，我很高兴向大家宣布我做到了！！

鉴于fastjson优越的性能表现，我建议做如下事情；

1、替换其他所有的json库，java世界里没有其他的json库能够和fastjson可相比了。

2、使用fastjson的序列化和反序列化替换java serialize，java serialize不单性能慢，而且体制大。

3、使用fastjson替换hessian，json协议不必hessian体积大，而且fastjson性能优越，数倍于hessian

4、把fastjson用于memached缓存对象数据。

How to get it?

If you're Maven user, just use our maven repository(http://code.alibabatech.com/mvn/releases/)
with folloging dependency

<span style="font-size:13px"><dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.1.1</version>
</dependency>
</span>

Downlaods

Binary : http://code.alibabatech.com/mvn/releases/com/alibaba/fastjson/1.1.1/fastjson-1.1.1.jar

Source :http://code.alibabatech.com/mvn/releases/com/alibaba/fastjson/1.1.1/fastjson-1.1.1-sources.jar

Subversion : http://code.alibabatech.com/svn/fastjson/