springboot 容器启动事件

在springboot 容器启动时，我们需要在启动过程中做一些操作，比如启动容器后，执行某些代码。

spring 提供了监听器，我们可以方便的实现这些操作。

在容器启动开始时：

package com.neo.filter;

import org.springframework.boot.context.event.ApplicationStartingEvent;
import org.springframework.context.ApplicationListener;

public class ApplicationStartingEventListener implements ApplicationListener<ApplicationStartingEvent> {
    @Override
    public void onApplicationEvent(ApplicationStartingEvent arg0) {
        System.err.println("ApplicationStartingEventListener");
    }

}

在容器启动完成后执行操作：

package com.neo.filter;

import org.springframework.boot.context.event.ApplicationStartedEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.Ordered;

public class ApplicationStartedEventListener implements ApplicationListener<ApplicationStartedEvent>,Ordered {

    @Override
    public void onApplicationEvent(ApplicationStartedEvent ev) {
        System.out.println("ApplicationStartedEventListener1");
    }
    @Override
    public int getOrder() {
        return 1;
    }

}

如果需要有顺序执行，我们可以实现Ordered接口，只越小，越先执行。

package com;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import com.neo.filter.ApplicationStartedEventListener;
import com.neo.filter.ApplicationStartedEventListener2;
import com.neo.filter.ApplicationStartingEventListener;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication app=new SpringApplication(DemoApplication.class);
        app.addListeners(new ApplicationStartedEventListener());
        app.addListeners(new ApplicationStartingEventListener());
        app.addListeners(new ApplicationStartedEventListener2());
        app.run(args);
    }
}