spring-事件

spring事件类型：ApplicationEvent

spring事件监听器： ApplicationListener

spring事件广播器： ApplicationEventMulticaster

监听所有spring事件：

public class SpringEventDemo {
    public static void main(String[] args) {
        GenericApplicationContext context = new GenericApplicationContext();
        context.addApplicationListener(new ApplicationListener<ApplicationEvent>() {
            @Override
            public void onApplicationEvent(ApplicationEvent event) {
                System.err.println(event);
            }
        });
        context.refresh(); //ContextRefreshedEvent
        context.publishEvent("first"); //PayloadApplicationEvent
        context.publishEvent(new MyEvent("myEvent")); //SpringEventDemo$MyEvent
        context.close(); //ContextClosedEvent
    }

    private static class MyEvent extends ApplicationEvent{

        /**
         * Create a new ApplicationEvent.
         *
         * @param source the object on which the event initially occurred (never {@code null})
         */
        public MyEvent(Object source) {
            super(source);
        }
    }

}

打印结果：

org.springframework.context.event.ContextRefreshedEvent[source=org.springframework.context.support.GenericApplicationContext@707f7052, started on Sun Sep 22 21:25:19 CST 2019]
21:25:20.225 [main] DEBUG org.springframework.context.support.GenericApplicationContext - Closing org.springframework.context.support.GenericApplicationContext@707f7052, started on Sun Sep 22 21:25:19 CST 2019
org.springframework.context.PayloadApplicationEvent[source=org.springframework.context.support.GenericApplicationContext@707f7052, started on Sun Sep 22 21:25:19 CST 2019]
com.example.springbootdemo.SpringEventDemo$MyEvent[source=myEvent]
org.springframework.context.event.ContextClosedEvent[source=org.springframework.context.support.GenericApplicationContext@707f7052, started on Sun Sep 22 21:25:19 CST 2019]

监听某个事件：

public class SpringEventDemo {
    public static void main(String[] args) {
        GenericApplicationContext context = new GenericApplicationContext();
//        context.addApplicationListener(new ApplicationListener<ApplicationEvent>() {
//            @Override
//            public void onApplicationEvent(ApplicationEvent event) {
//                System.err.println(event);
//            }
//        });
        context.addApplicationListener(new MyEventListener());
        context.refresh(); //ContextRefreshedEvent
        context.publishEvent("first"); //PayloadApplicationEvent
        context.publishEvent(new MyEvent("myEvent")); //SpringEventDemo$MyEvent
        context.close(); //ContextClosedEvent
    }

    private static class MyEvent extends ApplicationEvent{

        /**
         * Create a new ApplicationEvent.
         *
         * @param source the object on which the event initially occurred (never {@code null})
         */
        public MyEvent(Object source) {
            super(source);
        }
    }

    private static class MyEventListener implements ApplicationListener<MyEvent>{

        @Override
        public void onApplicationEvent(MyEvent event) {
            System.err.println(event);
        }
    }

}

输出结果：

com.example.springbootdemo.SpringEventDemo$MyEvent[source=myEvent]

public class DemoApplication {

    public static void main(String[] args) {
        ApplicationEventMulticaster multicaster = new SimpleApplicationEventMulticaster();
        multicaster.addApplicationListener(event -> {
            if(event instanceof PayloadApplicationEvent){
                System.out.println("接收到payloadApplicationEvent");
            }else {
                System.out.println("接收到事件");
            }

        });

        multicaster.multicastEvent(new PayloadApplicationEvent<>("1","yin"));
        multicaster.multicastEvent(new MyEvent("myevent"));
    }

    private static class MyEvent extends ApplicationEvent{

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

}

输出结果：

接收到payloadApplicationEvent
接收到事件