Spring事件通知机制介绍

发布时间：2021-12-10 18:17:47 所属栏目：PHP教程来源：互联网

导读：优势解耦对同一种事件有多种处理方式不干扰主线(main line) 起源要讲spring的事件通知机制，就要先了解一下spring中的这些接口和抽象类： ApplicationEventPublisherAware 接口:用来 publish event ApplicationEvent 抽象类，记录了source和初始化时间戳

优势

解耦
对同一种事件有多种处理方式
不干扰主线(main line)
起源

要讲spring的事件通知机制，就要先了解一下spring中的这些接口和抽象类：

ApplicationEventPublisherAware        接口:用来 publish event
ApplicationEvent                  抽象类，记录了source和初始化时间戳：用来定义Event
ApplicationListener<E extends ApplicationEvent> :用来监听事件
构建自己的事件机制案例

测试案例

测试入口

package com.meituan.spring.testcase.listener;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.concurrent.TimeUnit;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:40.
* -----------------------------
* Desc:
*/
public class TestPortal {
  public static void main(String[] args) throws InterruptedException {

      final ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-config.xml");

      String[] definitionNames = applicationContext.getBeanDefinitionNames();
      System.out.println("==============bean====start=================");
      for (String definitionName : definitionNames) {
        System.out.println("bean----:" + definitionName);
      }
      System.out.println("==============bean====end=================");
      System.out.println();
      final CustomizePublisher customizePublisher = applicationContext.getBean(CustomizePublisher.class);

      Thread thread = new Thread(new Runnable() {
        @Override
        public void run() {
            try {
              System.out.println("开始吃饭：");

              MealEvent lunchEvent = new MealEvent("A吃午饭了", MealEnum.lunch);
              MealEvent breakfastEvent = new MealEvent("B吃早饭了", MealEnum.breakfast);
              MealEvent dinnerEvent = new MealEvent("C吃晚饭了", MealEnum.dinner);
              customizePublisher.publish(lunchEvent);
              TimeUnit.SECONDS.sleep(1l);
              customizePublisher.publish(breakfastEvent);
              TimeUnit.SECONDS.sleep(1l);
              customizePublisher.publish(dinnerEvent);
              TimeUnit.SECONDS.sleep(1l);

              System.out.println("他们吃完了！");
            } catch (InterruptedException e) {
              e.printStackTrace();
            }
        }
      });
      thread.setName("meal-thread");
      thread.start();

      System.out.println(Thread.currentThread().getName() + " is waiting for ....");
      thread.join();
      System.out.println("Done!!!!!!!!!!!!");
  }
}

TestPortal

测试结果

测试成员
MealListener ：MealEvent                  演员
TroubleListener ：TroubleEvent         演员
AllAcceptedListener                            演员
MealEnum                                          道具
TestPortal                                           入口
CustomizePublisher                           导演
成员代码
接受全部事件的演员（很负责任啊）

package com.meituan.spring.testcase.listener;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:27.
* -----------------------------
* Desc:
*/
@Component
public class AllAcceptedListener implements ApplicationListener<ApplicationEvent> {
  @Override
  public void onApplicationEvent(ApplicationEvent event) {
      System.out.println(">>>>>>>>>>>>>>>>event:" + event);
  }
}

AllAcceptedListener

导演负责分发事件

package com.meituan.spring.testcase.listener;

import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.stereotype.Component;

/**
* Created by zhangxiaoguang on 16/1/28 上午1:41.
* -----------------------------
* Desc:
*/
@Component
public class CustomizePublisher implements ApplicationEventPublisherAware {

  private ApplicationEventPublisher applicationEventPublisher;

  public void publish(MealEvent event) {
      applicationEventPublisher.publishEvent(event);
  }

  @Override
  public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
      this.applicationEventPublisher = applicationEventPublisher;
  }
}

CustomizePublisher

负责处理吃饭事件的演员

package com.meituan.spring.testcase.listener;

import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:27.
* -----------------------------
* Desc:
*/
@Component
public class MealListener implements ApplicationListener<MealEvent> {
  @Override
  public void onApplicationEvent(MealEvent event) {
      System.out.println(String.format(">>>>>>>>>>>thread:%s,type:%s,event:%s",
            Thread.currentThread().getName(), event.getMealEnum(), event));

      dispatchEvent(event);
  }

  private void dispatchEvent(MealEvent event) {
      switch (event.getMealEnum()) {
        case breakfast:
            System.out.println(event.getMealEnum() + " to handle!!!");
            break;
        case lunch:
            System.out.println(event.getMealEnum() + " to handle!!!");
            break;
        case dinner:
            System.out.println(event.getMealEnum() + " to handle!!!");
            break;
        default:
            System.out.println(event.getMealEnum() + " error!!!");
            break;
      }
  }
}

MealListener

吃饭消息

package com.meituan.spring.testcase.listener;

import org.springframework.context.ApplicationEvent;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:24.
* -----------------------------
* Desc:吃饭事件
*/
public class MealEvent extends ApplicationEvent {

  private MealEnum mealEnum;

  /**
    * @param mealContent
    *        吃什么
    * @param mealEnum
    *        早餐还是午餐？
    */
  public MealEvent(String mealContent, MealEnum mealEnum) {
      super(mealContent);
      this.mealEnum = mealEnum;
  }

  public MealEnum getMealEnum() {
      return mealEnum;
  }
}

MealEvent

工具

package com.meituan.spring.testcase.listener;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:29.
* -----------------------------
* Desc:
*/
public enum MealEnum {
  breakfast,
  lunch,
  dinner
}

MealEnum

令人厌烦的演员

package com.meituan.spring.testcase.listener;

import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:27.
* -----------------------------
* Desc:
*/
@Component
public class TroubleListener implements ApplicationListener<TroubleEvent> {
  @Override
  public void onApplicationEvent(TroubleEvent event) {
      System.out.println(">>>>>>>>>>>>>>>>event:" + event);
  }
}

TroubleListener

令人厌烦的事件

package com.meituan.spring.testcase.listener;

import org.springframework.context.ApplicationEvent;

/**
* Created by zhangxiaoguang on 16/1/27 下午11:24.
* -----------------------------
* Desc:令人厌烦的事件
*/
public class TroubleEvent extends ApplicationEvent {
  public TroubleEvent(Object source) {
      super(source);
  }
}

TroubleEvent

总结

详细定制 event 类型的，则相关定制的listener会处理对应的消息，其他listener不会管闲事；

制定顶级 event 类型的，ApplicationEvent的，则会处理所有的事件。

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