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 eventApplicationEvent 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。
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