public class EventPublishingRunListener implements SpringApplicationRunListener, Ordered {
private final SpringApplication application;
private final String[] args;
// 拥有一个SimpleApplicationEventMulticaster事件广播器来广播事件
private final SimpleApplicationEventMulticaster initialMulticaster;
public EventPublishingRunListener(SpringApplication application, String[] args) {
this.application = application;
this.args = args;
// 新建一个事件广播器SimpleApplicationEventMulticaster对象
this.initialMulticaster = new SimpleApplicationEventMulticaster();
// 遍历在构造SpringApplication对象时从spring.factories配置文件中获取的事件监听器
for (ApplicationListener<?> listener : application.getListeners()) {
// 将从spring.factories配置文件中获取的事件监听器们添加到事件广播器initialMulticaster对象的相关集合中
this.initialMulticaster.addApplicationListener(listener);
}
}
@Override
public int getOrder() {
return 0;
}
// 发射ApplicationStartingEvent事件
@Override
public void starting() {
this.initialMulticaster.multicastEvent(
new ApplicationStartingEvent(this.application, this.args));
}
// 发射ApplicationEnvironmentPreparedEvent事件
@Override
public void environmentPrepared(ConfigurableEnvironment environment) {
this.initialMulticaster.multicastEvent(new ApplicationEnvironmentPreparedEvent(
this.application, this.args, environment));
}
// 发射ApplicationContextInitializedEvent事件
@Override
public void contextPrepared(ConfigurableApplicationContext context) {
this.initialMulticaster.multicastEvent(new ApplicationContextInitializedEvent(
this.application, this.args, context));
}
// 发射ApplicationPreparedEvent事件
@Override
public void contextLoaded(ConfigurableApplicationContext context) {
for (ApplicationListener<?> listener : this.application.getListeners()) {
if (listener instanceof ApplicationContextAware) {
((ApplicationContextAware) listener).setApplicationContext(context);
}
context.addApplicationListener(listener);
}
this.initialMulticaster.multicastEvent(
new ApplicationPreparedEvent(this.application, this.args, context));
}
// 发射ApplicationStartedEvent事件
@Override
public void started(ConfigurableApplicationContext context) {
context.publishEvent(
new ApplicationStartedEvent(this.application, this.args, context));
}
// 发射ApplicationReadyEvent事件
@Override
public void running(ConfigurableApplicationContext context) {
context.publishEvent(
new ApplicationReadyEvent(this.application, this.args, context));
}
// 发射ApplicationFailedEvent事件
@Override
public void failed(ConfigurableApplicationContext context, Throwable exception) {
ApplicationFailedEvent event = new ApplicationFailedEvent(this.application,
this.args, context, exception);
if (context != null && context.isActive()) {
// Listeners have been registered to the application context so we should
// use it at this point if we can
context.publishEvent(event);
}
else {
// An inactive context may not have a multicaster so we use our multicaster to
// call all of the context's listeners instead
if (context instanceof AbstractApplicationContext) {
for (ApplicationListener<?> listener : ((AbstractApplicationContext) context)
.getApplicationListeners()) {
this.initialMulticaster.addApplicationListener(listener);
}
}
this.initialMulticaster.setErrorHandler(new LoggingErrorHandler());
this.initialMulticaster.multicastEvent(event);
}
}
// ...省略非关键代码
}
