Spring Boot中使用SpringEvent组件

Spring的事件机制是基于观察者模式的实现，主要由以下三个部分组成：

事件（Event）：事件是应用中发生的重要事情，通常是一个继承自ApplicationEvent的类。

事件发布器（Publisher）：发布事件的对象，通常是Spring的应用上下文（ApplicationContext）。

事件监听器（Listener）：监听并处理事件的对象，通常是实现了ApplicationListener接口的类。

同步方法

创建自定义事件，自定义事件需要继承ApplicationEvent类，并添加相应的属性和构造方法

package com.ssdl.baize.pub;import org.springframework.context.ApplicationEvent;public class CustomEvent extends ApplicationEvent {private String message;public CustomEvent(Object source, String message) {super(source);this.message = message;}public String getMessage() {return message;}
}

创建事件监听器，用于监听和处理自定义事件。事件监听器需要实现ApplicationListener接口，并覆盖onApplicationEvent方法。

package com.ssdl.baize.pub;import lombok.extern.slf4j.Slf4j;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;@Component
@Slf4j
public class CustomEventListener implements ApplicationListener<CustomEvent> {@Overridepublic void onApplicationEvent(CustomEvent event) {try {Thread.sleep(5000L);} catch (InterruptedException e) {e.printStackTrace();}log.info("休眠5秒");log.info("Received custom event - {}" , event.getMessage());}
}

3.发布事件，要在某个组件中注入ApplicationEventPublisher，并调用其publishEvent方法。

package com.ssdl.baize.pub;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Component;@Component
public class CustomEventPublisher {@Autowiredprivate ApplicationEventPublisher applicationEventPublisher;public void publishEvent(String message) {CustomEvent customEvent = new CustomEvent(this, message);applicationEventPublisher.publishEvent(customEvent);}
}

4.测试

	@Autowiredprivate CustomEventPublisher customEventPublisher;@GetMapping(path = "/pub")@ApiOperation(value = "发布订阅")public String pub(@RequestParam("message") String message) {log.info("start");customEventPublisher.publishEvent(message);log.info("发送完成!!!");return "OK";}

5.结果
在这里插入图片描述

异步方法
说明：创建自定义事件、发布事件、测试这三个如同步方法一样，只需要更改创建事件监听器即可

package com.ssdl.baize.pub;import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;@Configuration
@EnableAsync
public class AsyncConfig {
}

package com.ssdl.baize.pub;import lombok.extern.slf4j.Slf4j;
import org.springframework.context.event.EventListener;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;@Component
@Slf4j
public class AsyncCustomEventListener {@Async@EventListener(condition = "#event.message.startsWith('filter')")public void handleCustomEvent(CustomEvent event) {try {Thread.sleep(5000L);} catch (InterruptedException e) {e.printStackTrace();}log.info("休眠5秒");log.info("Async received custom event - {}" , event.getMessage());}
}