Spring Boot 创建注册Servlet ，Listener ， Filter Spring Boot 添加Servlet Spring Boot 添加Listener Spring Boo

╰半夏微凉° 2022-11-06 04:59 126阅读 0赞

##     Spring Boot 创建注册Servlet ，Listener ， Filter Spring Boot 添加Servlet  Spring Boot 添加Listener  Spring Boot 添加Filter  ##

**一、 前言**

在传统的Spring项目中，添加 Servlet 等，需要在 **web.xml** 文件中进行配置，分别使用3个对应的标签 **<servlet>、<filter>、<listener>** ， 在Spring Boot项目中，一般是没有web.xml 文件，那么该如何实现呢？

**二、Spring Boot 注册Servlet**

1、 创建MyServlet 类 继承 javax.servlet.http.HttpServlet ，重写执行方法

import java.io.IOException;
    import java.util.Date;
    import javax.servlet.ServletException;
    import javax.servlet.ServletOutputStream;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    /**
     * description: 添加一个Servlet
     * @version v1.0
     * @author w
     * @date 2021年3月5日上午10:56:19
     **/
    public class MyServlet extends HttpServlet {
    
    	private static final long serialVersionUID = 1L;
    	
    	@Override
    	protected void doPost(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException {
    		response.reset();
    		response.setContentType("application/json;charset=UTF-8");
    		response.setCharacterEncoding("UTF-8");
    		String res = "这是来自于Servlet的请求！"+ new Date().getTime();
    		ServletOutputStream outputStream = response.getOutputStream();
    		outputStream.write(res.getBytes());
    		outputStream.flush();
    		outputStream.close();
    	}
    	
    	@Override
    	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    		doPost(req, resp);
    	}
    }

2、创建MyServletConfig 类，注册Servlet

import org.springframework.boot.web.servlet.ServletRegistrationBean;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    /**
     * description: 注册Servlet
     * @version v1.0
     * @author w
     * @date 2021年3月5日上午11:03:19
     **/
    @Configuration
    public class MyServletConfig {
    	
    	@Bean
    	public ServletRegistrationBean myServlet() {
    		return new ServletRegistrationBean(new MyServlet() , "/myServlet" );
    	}
    }

**三、Spring Boot注册Filter**

1、创建 MyFilter类 实现 javax.servlet.Filter 接口

import java.io.IOException;
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    
    /**
     * description: 自定义过滤器 MyFilter
     * @version v1.0
     * @author w
     * @date 2021年3月5日上午11:45:30
     **/
    public class MyFilter implements Filter {
    	@Override
    	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    			throws IOException, ServletException {
    		System.out.println("  myFilter  running .... ");
    		chain.doFilter(request, response);
    	}
    }

2、创建MyFilterConfig 类 ，注册 Filter

import org.springframework.boot.web.servlet.FilterRegistrationBean;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    /**
     * description: 注册MyFilter
     * @version v1.0
     * @author w
     * @date 2021年3月5日上午11:59:18
     **/
    @Configuration
    public class MyFilterConfig {
    
    	@Bean
    	public FilterRegistrationBean myFilter() {
    		FilterRegistrationBean register = new FilterRegistrationBean();
    		register.setFilter(new MyFilter());
    		register.addUrlPatterns("/*"); // 过滤所有请求
    		register.setOrder(1);
    		return register ;
    	}
    }

**四、Spring Boot注册Listener**

1、创建 MyListener 类，分别实现 ServletContextListener 、 HttpSessionListener 、ServletRequestListener 接口

import javax.servlet.ServletContextEvent;
    import javax.servlet.ServletContextListener;
    import javax.servlet.ServletRequestEvent;
    import javax.servlet.ServletRequestListener;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpSession;
    import javax.servlet.http.HttpSessionEvent;
    import javax.servlet.http.HttpSessionListener;
    
    /**
     * description:  添加监听器  MyListener
     * @version v1.0
     * @author w
     * @date 2021年3月5日下午1:18:35
     **/
    public class MyListener implements ServletContextListener , HttpSessionListener , ServletRequestListener {
    	
    	@Override
    	public void contextDestroyed(ServletContextEvent sce) {
    		//销毁Servlet上下文时调用 --- 热更新的时候，会销毁
    		System.out.println(" 监听器销毁 ....  destroyed ");
    	}
    	
    	@Override
    	public void contextInitialized(ServletContextEvent sce) {
            //加载Servlet上下文时调用
    		System.out.println( " 监听器启动 .....  initialized  ");
    	}
    	
    	 @Override
        public void requestDestroyed(ServletRequestEvent arg0) {
            //销毁Request时调用
            HttpServletRequest request=(HttpServletRequest)arg0.getServletRequest();
            long time=System.currentTimeMillis()-(long)request.getAttribute("dateCreated");
            System.out.println(request.getRemoteAddr()+"请求处理结束，用时"+time+"毫秒。");
        }
    
        @Override
        public void requestInitialized(ServletRequestEvent arg0) {
            //创建Request时调用
            HttpServletRequest request=(HttpServletRequest) arg0.getServletRequest();
            String uri=request.getRequestURI();
            uri=request.getQueryString()==null?uri:(uri+"?"+request.getQueryString());
            request.setAttribute("dateCreated", System.currentTimeMillis());
            System.out.println("IP:"+request.getRemoteAddr()+" 请求 "+uri);
        }
    	    
    
        @Override
        public void sessionCreated(HttpSessionEvent arg0) {
            //创建session时调用
            HttpSession session =arg0.getSession();
            System.out.println("新创建一个session，ID为："+session.getId());
        }
    
        @Override
        public void sessionDestroyed(HttpSessionEvent arg0) {
            //销毁session前调用
            HttpSession session =arg0.getSession();
            System.out.println("销毁一个session，ID为："+session.getId());
        }
    }

2、创建 MyListenerConfig 类，注册 Listener

@Configuration
    public class MyListenerConfig {
    
    	@Bean
    	public ServletListenerRegistrationBean myListener() {
    		ServletListenerRegistrationBean listener = new ServletListenerRegistrationBean();
    		listener.setEnabled(true); // default true
    		listener.setListener(new MyListener());
    		listener.setOrder(1);
    		return listener;
    	}
    	
    }

参考资料：[Spring中@Component与@Bean的区别][Spring_Component_Bean]

[Spring_Component_Bean]: https://www.jianshu.com/p/3fbfbb843b63