Spring - 自定义事件

下面通过一个具体的例子来说明如何创建自定义事件：

CustomEvent.java

package com.soygrow.CustomEvent;

import org.springframework.context.ApplicationEvent;

public class CustomEvent extends ApplicationEvent {
    public CustomEvent(Object source) {
        super(source);
    }

    public String toString() {
        return "My Custom Event";
    }
}

扩展ApplicationEvent，创建自定义事件类CustomEvent，这个类必须有一个默认构造函数，并实现父类的构造。

CustomEventPublisher.java

package com.soygrow.CustomEvent;

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

public class CustomEventPublisher implements ApplicationEventPublisherAware {
    private ApplicationEventPublisher publisher;

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

    public void publish() {
        CustomEvent ce = new CustomEvent(this);
        publisher.publishEvent(ce);
    }
}

自定义事件定义成功后，你可以从任何类中发布它，所以需要实现ApplicationEventPublisherAware接口

CustomEventHandler.java

package com.soygrow.CustomEvent;

import org.springframework.context.ApplicationListener;

public class CustomEventHandler implements ApplicationListener<CustomEvent> {
    @Override
    public void onApplicationEvent(CustomEvent customEvent) {
        System.out.println(customEvent.toString());
    }
}

上面代码是发布一个事件。

MainApp.java

package com.soygrow.CustomEvent;

import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
    public static void main(String[] args) {
        ConfigurableApplicationContext context =
                new ClassPathXmlApplicationContext("CustomEventBeans.xml");

        CustomEventPublisher cvp =
                (CustomEventPublisher) context.getBean("customEventPublisher");

        cvp.publish();
        cvp.publish();
    }
}

CustomEventBeans.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="customEventHandler" class="com.soygrow.CustomEvent.CustomEventHandler"/>
    <bean id="customEventPublisher" class="com.soygrow.CustomEvent.CustomEventPublisher"/>
</beans>

如果一切正常，那么运行的结果是：

My Custom Event
My Custom Event