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public ConfigurableApplicationContext (String... args) {
StopWatch stopWatch = new StopWatch();
stopWatch.start();
ConfigurableApplicationContext context = null;
FailureAnalyzers analyzers = null;
this.configureHeadlessProperty();
SpringApplicationRunListeners listeners = this.getRunListeners(args);
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
ConfigurableEnvironment environment = this.prepareEnvironment(listeners, applicationArguments);
Banner printedBanner = this.printBanner(environment);
context = this.createApplicationContext();
new FailureAnalyzers(context);
this.prepareContext(context, environment, listeners, applicationArguments, printedBanner);
this.refreshContext(context);
this.afterRefresh(context, applicationArguments);
listeners.finished(context, (Throwable)null);
stopWatch.stop();
if (this.logStartupInfo) {
(new StartupInfoLogger(this.mainApplicationClass)).logStarted(this.getApplicationLog(), stopWatch);
}
return context;
} catch (Throwable var9) {
this.handleRunFailure(context, listeners, (FailureAnalyzers)analyzers, var9);
throw new IllegalStateException(var9);
}
}
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核心步骤一：启动 SpringApplicationRunListener
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SpringApplicationRunListeners listeners = this.getRunListeners(args);
listeners.starting();
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SpringApplicationRunListener 接口：
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public interface SpringApplicationRunListener {
void starting();
void environmentPrepared(ConfigurableEnvironment var1);
void contextPrepared(ConfigurableApplicationContext var1);
void contextLoaded(ConfigurableApplicationContext var1);
void finished(ConfigurableApplicationContext var1, Throwable var2);
}
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SpringApplicationRunListener 接口目前只有 EventPublishingRunListener 一个实现类。
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private SpringApplicationRunListeners getRunListeners(String[] args) {
Class<?>[] types = new Class[]{SpringApplication.class, String[].class};
return new SpringApplicationRunListeners(logger, this.getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
}
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同理也是实例化 SpringApplicationRunListener 接口实现类，最终实际是调用 EventPublishingRunListener 的 starting() 方法：
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public void starting() {
this.initialMulticaster.multicastEvent(new ApplicationStartedEvent(this.application, this.args));
}
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最终调用：
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public void multicastEvent(final ApplicationEvent event, ResolvableType eventType) {
ResolvableType type = eventType != null ? eventType : this.resolveDefaultEventType(event);
Iterator var4 = this.getApplicationListeners(event, type).iterator();
while(var4.hasNext()) {
final ApplicationListener<?> listener = (ApplicationListener)var4.next();
Executor executor = this.getTaskExecutor();
if (executor != null) {
executor.execute(new Runnable() {
public void () {
SimpleApplicationEventMulticaster.this.invokeListener(listener, event);
}
});
} else {
this.invokeListener(listener, event);
}
}
}
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SpringApplicationRunListener 会被构建为 AppicationEvent，然后被 ApplicationEventMulticaster 广播，最后转变为 ApplicationListener。
这中间比较复杂，看的也不是特别的深入，后续继续深入分析。
原文:大专栏 Spring Boot 启动源码解析系列六：执行启动方法一