spring 事件

applicationContext 的事件機制是觀察者設計模式，經過ApplicationEvent 類，和ApplicationListener 接口，能夠實現ApplicationContext 的事件處理，若是容器中有一個ApplicationListener Bean每當ApplicationContext發佈ApplicationEvent時，ApplicationListener Bean將自動被觸發：

Spring 內置事件：

• ContextRefreshedEvent：當ApplicationContext初始化或者刷新時觸發該事件。
•   ContextClosedEvent：當ApplicationContext被關閉時觸發該事件。容器被關閉時，其管理的全部單例Bean都被銷燬。
• RequestHandleEvent：在Web應用中，當一個http請求（request）結束觸發該事件。
• ContestStartedEvent：Spring2.5新增的事件，當容器調用ConfigurableApplicationContext的Start()方法開始/從新開始容器時觸發該事件。
• ContestStopedEvent：Spring2.5新增的事件，當容器調用ConfigurableApplicationContext的Stop()方法中止容器時觸發該事件。
• SessionConnectedEvent 爲WebSocket 功能服務
• SessionConnectEvent 爲WebSocket 功能服務
• SessionDisconnectEvnet  爲WebSocket 功能服務

例1

監聽當spring容器的啓動

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.ApplicationListener;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.stereotype.Component;


@Component
public class SpringRefreshedEventListener implements ApplicationListener<ContextRefreshedEvent> {
    private final Logger logger = LoggerFactory.getLogger(SpringRefreshedEventListener.class);


    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
        logger.debug("spring 容器已經就緒。。。。");
    }
}

 

例2：

發佈事件：

//自定義事件

import org.springframework.context.ApplicationEvent;

public class MyEvent extends ApplicationEvent {

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

}

//發佈自定義事件
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

@Component
public class MyEventPublisher implements ApplicationContextAware {

    private ApplicationContext applicationContext;

    public void publish(){
        MyEvent myEvent = new MyEvent(null);
        applicationContext.publishEvent(myEvent);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }


}

 

例3

發佈事件：

Publisher類實現  org.springframework.context.ApplicationEventPublisherAware 接口

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


@Component
public class MyEventPublisherII implements ApplicationEventPublisherAware {

    private ApplicationEventPublisher applicationEventPublisher;

    public void publish(){
        MyEvent myEvent = new MyEvent(null);
        applicationEventPublisher.publishEvent(myEvent);
    }

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