自定义Spring event

通过Spring自定义event

首先我们定义我们的event类

package com.hyenas.spring.custom.event;

import org.springframework.context.ApplicationEvent;

public class CustomEvent extends ApplicationEvent{
    
    private static final long serialVersionUID = -82737763905791865L;

    public CustomEvent(Object source) {
        super(source);
    }

    @Override
    public String toString() {
        return "my custom event";
    }


}

然后我们实现一个ApplicationListener ,这个ApplicationListener是带泛型的，带入我们自定义的event类

package com.hyenas.spring.custom.event;

import org.springframework.context.ApplicationListener;

public class CustomEventHandler implements ApplicationListener<CustomEvent>{

    @Override
    public void onApplicationEvent(CustomEvent event) {
        System.out.println(event.toString());
    }

}

最后我们实现一个Publisher。

package com.hyenas.spring.custom.event;

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

public class CustomEventPublisher implements  ApplicationEventPublisherAware {
    
    private ApplicationEventPublisher publisher;
    
    @Override
    public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {
        this.publisher = publisher;
    }
    
    
    public void publish() {
        CustomEvent event = new CustomEvent(this);
        publisher.publishEvent(event);
    }

}

在这里我们也可以实现一个ApplicationContextAware,因为ApplicationContext接口也是继承了我们的ApplicationEventPublisher接口的。Spring源码如下

public interface ApplicationContext extends ListableBeanFactory, HierarchicalBeanFactory,
        MessageSource, ApplicationEventPublisher, ResourcePatternResolver

我们实现ApplicationContextAware的话，会往我们的程序中setApplicationContext，ApplicationContext同样可以publishEvent

然后，我们定义我们的spring xml文件custom-event.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-3.0.xsd">

   <bean id="customEventHandler" 
      class="com.hyenas.spring.custom.event.CustomEventHandler"/>

   <bean id="customEventPublisher" 
      class="com.hyenas.spring.custom.event.CustomEventPublisher"/>

</beans>

好，最后我们写一个MainApp测试一下我们的程序吧。

package com.hyenas.spring.custom.event;

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

public class MainApp {
     private static ConfigurableApplicationContext context;

    public static void main(String[] args) {
          context = new ClassPathXmlApplicationContext("custom-event.xml");
          
          CustomEventPublisher cvp = 
          (CustomEventPublisher) context.getBean("customEventPublisher");
          cvp.publish();  
          cvp.publish();
       }
}

运行结果

my custom event
my custom event

这样我们就完成了整个event从建立，到触发的过程。