时间：2020-10-30 14:20:41 | 栏目：JAVA代码 | 点击：次
在使用Spring框架开发时, 有时我们需要在spring容器初始化完成后做一些操作, 那么我们可以通过自定义ApplicationListener 来实现.
自定义监听器
@Component
public class MyApplicationListener implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
// 获取spring 上下文
ApplicationContext applicationContext = contextRefreshedEvent.getApplicationContext();
// do your work...
}
源码分析
springboot 启动应用, 执行 SpringApplication.run(String… args) 方法
run方法中执行完初始化上下文方法后, 会执行this.refreshContext方法, 刷新
经过一堆方法跳转, 执行 AbstractApplicationContextl类的publishEvent(Object event, @Nullable ResolvableType eventType) 方法
然后执行 SimpleApplicationEventMulticaster.multicastEvent(ApplicationEvent event, @Nullable ResolvableType eventType)
然后依次执行所有监听器的onApplicationEvent()方法
// 遍历所有ApplicationListeners, 依次执行ApplicationListener 的onApplicationEvent()方法
public void multicastEvent(ApplicationEvent event, @Nullable ResolvableType eventType) {
ResolvableType type = eventType != null ? eventType : this.resolveDefaultEventType(event);
Iterator var4 = this.getApplicationListeners(event, type).iterator();
while(var4.hasNext()) {
ApplicationListener<?> listener = (ApplicationListener)var4.next();
Executor executor = this.getTaskExecutor();
if (executor != null) {
executor.execute(() -> {
this.invokeListener(listener, event);
});
} else {
this.invokeListener(listener, event);
}
}
}