springboot启动的类为SpringApplication,执行构造函数初始化属性值后进入run方法:
然后返回ConfigurableApplicationContext(spring应用)。
ConfigurableApplicationContext结构图如下:
1.SpringApplicationRunListeners listeners = getRunListeners(args),获取springboot应用监听器,可以主要看SpringApplicationRunListener接口做的一些工作。
2.加载配置Spring环境信息
3.配置上下文信息
重点:SpringFactoriesLoader
getSpringFactoriesInstances在SpringApplication的构造方法中调用了两次
getRunListeners(args):
private SpringApplicationRunListeners getRunListeners(String[] args) {
Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class };
return new SpringApplicationRunListeners(logger,
getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
}
getSpringFactoriesInstances
getSpringFactoriesInstances在第一次被调用时会将类路径下所有的META-INF/spring.factories的文件中的属性进行加载并缓存到SpringFactoriesLoader的缓存cache中,下次被调用的时候就直接从SpringFactoriesLoader的cache中取数据了。这次就是从SpringFactoriesLoader的cache中取SpringApplicationRunListener类型的类(全限定名),然后实例化后返回
/**
* Run the Spring application, creating and refreshing a new
* {@link ApplicationContext}.
* @param args the application arguments (usually passed from a Java main method)
* @return a running {@link ApplicationContext}
*/
public ConfigurableApplicationContext run(String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
configureIgnoreBeanInfo(environment);
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
new Class[] { ConfigurableApplicationContext.class }, context);
prepareContext(context, environment, listeners, applicationArguments, printedBanner);
refreshContext(context);
afterRefresh(context, applicationArguments);
stopWatch.stop();
if (this.logStartupInfo) {
new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
}
listeners.started(context);
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
listeners.running(context);
}
catch (Throwable ex) {
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
未完…