java事件监听机制

在Java中，事件监听机制是通过注册监听器来响应事件的发生。事件源对象（event source）发生特定事件时，调用注册的监听器（event listener）中的相应方法。平时的开发中也经常会用到。

1.定义我们的事件类 CustomEvent ：

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;
    }
}

2.定义事件监听 CustomEventListener ：

import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

@Component
public class CustomEventListener {

    @EventListener
    public void handleCustomEvent(CustomEvent event) {
        //这里根据自己的业务场景，实现对应的业务逻辑
        System.out.println("Received custom event - " + event.getMessage());
    }
}

3.事件发布类  CustomEventPublisher：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.stereotype.Service;

@Service
public class CustomEventPublisher{

    @Autowired
    private ApplicationEventPublisher applicationEventPublisher;

    public void publishEvent(String message) {
        CustomEvent customEvent = new CustomEvent(this, message);
        applicationEventPublisher.publishEvent(customEvent);
    }
}

4.测试

@RestController
public class ListenerController {

    @Autowired
    private CustomEventPublisher customEventPublisher;


    @GetMapping("/testListener")
    public String triggerEvent(@RequestParam String message) {
        customEventPublisher.publishEvent(message);
        return "Event triggered!";
    }
}