spring：本地事件的應用

應用事件的觀察者模式，可以實作異步，功能解耦的目的，下面簡要說下spring中本地事件ApplicationEvent的用法。話不多說，直接上代碼：

定義一個Event,如下定義了一個新增事件，可以如法炮制定義别的事件

package com.example.event;

import org.springframework.context.ApplicationEvent;

public class AddEvent extends ApplicationEvent {
    private static final Long serialVersionUID = 1l;

    //    定義資訊
    private String message;

    //    繼承重寫構造方法
    public AddEvent(Object source,String message) {
        super(source);
        this.message = message;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }
}

           

1. 定義一個Listener，可以用EventListener注解來表示事件的處理操作：

package com.example.event;

import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

@Component
public class DemoListener{
    //    對消息進行處理
    @EventListener
    public void handleDemo(DemoEvent demoEvent) {
        String message = demoEvent.getMessage();
        System.out.println(message+" 已接受的資訊Demo");
    }

    @EventListener
    public void handleAdd(AddEvent demoEvent) {
        String message = demoEvent.getMessage();
        System.out.println(message+" 已接受的資訊Add");
    }

    @EventListener
    public void handleDelete(DeleteEvent demoEvent) {
        String message = demoEvent.getMessage();
        System.out.println(message+" 已接受的資訊Delete");
    }

    @EventListener
    public void handleUpdate(UpdateEvent demoEvent) {
        String message = demoEvent.getMessage();
        System.out.println(message+" 已接受的資訊Update");
    }
}
           

3.釋出事件：

package com.example.event;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.DependsOn;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

@Component
public class DemoPublisher {
    @Autowired
    private ApplicationContext applicationContext;

    public void publish(String message){
        applicationContext.publishEvent(new DemoEvent(this,message));
    }

    public void publishAdd(String message){
        applicationContext.publishEvent(new AddEvent(this,message));
    }

    public void publishDelete(String message){
        applicationContext.publishEvent(new DeleteEvent(this,message));
    }

    public void publishUpdate(String message){
        applicationContext.publishEvent(new UpdateEvent(this,message));
    }
}
           

1. 測試：

package com.example.demo;

import com.example.event.DemoPublisher;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ApplicationEvent {
	@Resource
	private DemoPublisher demoPublisher;
		@Test
	public void event(){
		demoPublisher.publish("你好嗎");

	}

	@Test
	public void event1(){
		demoPublisher.publishAdd("增加事件");

	}

	@Test
	public void event2(){
		demoPublisher.publishDelete("删除事件");

	}

	@Test
	public void event3(){
		demoPublisher.publishUpdate("更新事件");

	}
}
           

測試結果如下：