Java Spring 中的监听器Listener详解与实战教程

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class AppInitListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("应用初始化完成");
        // 执行应用初始化逻辑，例如加载配置文件
    }
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("应用销毁");
        // 执行应用销毁逻辑，例如释放资源
    }
}

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class SessionListener implements HttpSessionListener {
    @Override
    public void sessionCreated(HttpSessionEvent se) {
        System.out.println("会话创建，ID: " + se.getSession().getId());
        // 执行会话创建逻辑，例如记录用户登录信息
    }
    @Override
    public void sessionDestroyed(HttpSessionEvent se) {
        System.out.println("会话销毁，ID: " + se.getSession().getId());
        // 执行会话销毁逻辑，例如更新用户状态
    }
}

import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class RequestListener implements ServletRequestListener {
    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        System.out.println("请求初始化，URI: " + sre.getServletRequest().getRequestURI());
        // 执行请求初始化逻辑，例如记录请求开始时间
    }
    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        System.out.println("请求销毁，URI: " + sre.getServletRequest().getRequestURI());
        // 执行请求销毁逻辑，例如记录请求处理时间
    }
}

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;
    }
}

import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;
@Component
public class CustomEventListener implements ApplicationListener<CustomEvent> {
    @Override
    public void onApplicationEvent(CustomEvent event) {
        System.out.println("接收到自定义事件: " + event.getMessage());
        // 执行自定义事件的处理逻辑
    }
}

import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.stereotype.Component;
@Component
public class CustomEventPublisher implements ApplicationEventPublisherAware {
    private ApplicationEventPublisher publisher;
    @Override
    public void setApplicationEventPublisher(ApplicationEventPublisher publisher) {
        this.publisher = publisher;
    }
    public void publishCustomEvent(String message) {
        CustomEvent event = new CustomEvent(this, message);
        publisher.publishEvent(event);
    }
}