Spring事件监听实现了观察者模式。本Demo在junit4测试环境中实现

主要有三个类事件类、监听器类、事件发布类（入口）

事件类必须继承 ApplicationEvent，代码如下：

import org.junit.runner.RunWith;import org.springframework.context.ApplicationEvent;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;/** * Created by *** on 2016/3/15. */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext-indexConfig-test.xml")public class StudentAddEventTest extends ApplicationEvent {    private String sname;    public StudentAddEventTest(Object source, String sname) {        super(source);        this.sname = sname;    }    public String getSname() {        return sname;    }}

监听器Listener类需实现  ApplicationListener 接口  ApplicationListener可以传入一个泛型的事件类型变量，也可以不传。不传的话，需要在监听到事件发生时（onApplicationEvent）自己判断该事件是不是自己要监听的事件。

import org.junit.runner.RunWith;import org.springframework.context.ApplicationListener;import org.springframework.stereotype.Component;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;/** * Created by *** on 2016/3/15. */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext-indexConfig-test.xml")@Componentpublic class StudentAddListenerTest implements ApplicationListener
     
       {    @Override    public void onApplicationEvent(StudentAddEventTest studentAddEventTest) {        String sname = studentAddEventTest.getSname();        System.out.println("增加的学生的名字为：：："+sname);    }}
     

事件发布类实现了 ApplicationContextAware ，实现这个主要是为了拿到 ApplicationContext实例，进而调用他的 publishEvent方法。感觉不实现ApplicationContextAware应该也可以。。。

：

import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.beans.BeansException;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;import org.springframework.stereotype.Component;import org.springframework.test.context.ContextConfiguration;import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;/** * Created by *** on 2016/3/15. */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = "classpath:applicationContext-indexConfig-test.xml")@Componentpublic class StudentAddBeanTest implements ApplicationContextAware {    private static ApplicationContext applicationContext;    @Override    @Autowired    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {        this.applicationContext  = applicationContext;    }    public void addStudent(String sname){        StudentAddEventTest addEvent = new StudentAddEventTest(this, sname);        applicationContext.publishEvent(addEvent);    }    @Test    public void addTest(){        StudentAddBeanTest studentBean = new StudentAddBeanTest();        studentBean.addStudent("张三");        studentBean.addStudent("李四");    }}

需要注意的是 StudentAddListenerTest ——Listener类，StudentAddBeanTest ——事件发布类需在spring容器中注册，Demo中在 applicationContext-indexConfig-test.xml配置了

扫描<context:component-scan> </context:component-scan>路径

然后在类上加了注解@Component，运行测试方法addTest（）经过测试，能顺利实现既定目标。