SpringBoot实战分析(一) 入门级启动过程

1.启动类

@SpringBootApplication
public class DemoApplication {

public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}

public static ConfigurableApplicationContext run(Class<?> primarySource,
String... args) {
return run(new Class<?>[] { primarySource }, args);//断点
}

3.SpringApplication调用

public static ConfigurableApplicationContext run(Class<?>[] primarySources,
String[] args) {
return new SpringApplication(primarySources).run(args);//断点
}

public ConfigurableApplicationContext run(String... args) {
//java 查看时间和性能的类
//https://blog.csdn.net/pandawang1989/article/details/78246316
StopWatch stopWatch = new StopWatch();
stopWatch.start();
//定义配置上下文 是个interface 顶级父类包含BeanFactory
ConfigurableApplicationContext context = null;
//定义一个错误集合
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
//定义一个awt的headless
configureHeadlessProperty();
//获取一个run监听器
SpringApplicationRunListeners listeners = getRunListeners(args);
//启动监听
listeners.starting();
try {
//应用程序参数 初始化
ApplicationArguments applicationArguments = new DefaultApplicationArguments(
args);
//创建和配置环境 入参：监听 应用程序参数
ConfigurableEnvironment environment = prepareEnvironment(listeners,
applicationArguments);
//配置bean的忽略信息 扫描 spring.beaninfo.ignore 可选true/fale
//在application.yml中配置
configureIgnoreBeanInfo(environment);
//打印logo信息
Banner printedBanner = printBanner(environment);
//重点 重点 重点 说三遍
//创建app的上下文 初始化bean等操作都在这 后面再说
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(
SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
//准备 使用上下文
prepareContext(context, environment, listeners, applicationArguments,
printedBanner);
//刷新上下文  这个也是  重点 重点  重点
//synchronized (this.startupShutdownMonitor)
refreshContext(context);

afterRefresh(context, applicationArguments);
stopWatch.stop();

if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass)
.logStarted(getApplicationLog(), stopWatch);
}
//带上下文启动
listeners.started(context);
//应该是唤醒运行的线程
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}

try {
//发布事件
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}