Spring事件監聽Demo

Spring事件監聽實現了觀察者模式。本Demo在junit4測試環境中實現

主要有三個類事件類、監聽器類、事件發佈類（入口）

事件類必須繼承 ApplicationEvent，代碼以下：

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;
    }
}

監聽器Listener類需實現  ApplicationListener 接口  ApplicationListener能夠傳入一個泛型的事件類型變量，也能夠不傳。不傳的話，須要在監聽到事件發生時（onApplicationEvent）本身判斷該事件是否是本身要監聽的事件。

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")
@Component
public class StudentAddListenerTest implements ApplicationListener<StudentAddEventTest> {

    @Override
    public void onApplicationEvent(StudentAddEventTest studentAddEventTest) {
        String sname = studentAddEventTest.getSname();
        System.out.println("增長的學生的名字爲：：："+sname);
    }
}

事件發佈類實現了 ApplicationContextAware ，實現這個主要是爲了拿到 ApplicationContext實例，進而調用他的 publishEvent方法。感受不實現ApplicationContextAware應該也能夠。。。

：

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")
@Component
public 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("張三");
        studentBean.addStudent("李四");
    }

}

須要注意的是 StudentAddListenerTest ——Listener類，StudentAddBeanTest ——事件發佈類需在spring容器中註冊，Demo中在 applicationContext-indexConfig-test.xml配置了

掃描<context:component-scan> </context:component-scan>路徑

而後在類上加了註解@Component，運行測試方法addTest（）通過測試，能順利實現既定目標。