过滤器拦截方式的配置的代码

package cn.itcast.web.filter;

import java.io.IOException;

import javax.servlet.DispatcherType;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;

/**
 * 表示浏览器直接请求index.jsp资源时，过滤器会被执行
 * Servlet Filter implementation class FilterDemo5
 */
//@WebFilter(value="/index.jsp",dispatcherTypes=DispatcherType.REQUEST)
//只有转发访问index.jsp时，该过滤器才会被执行
//@WebFilter(value="/index.jsp",dispatcherTypes=DispatcherType.FORWARD)
//浏览器直接请求index.jsp和转发访问index.jsp都会被执行
//@WebFilter(value="/index.jsp",dispatcherTypes= {DispatcherType.FORWARD,DispatcherType.REQUEST})
@WebFilter(value="/*",dispatcherTypes= {DispatcherType.FORWARD,DispatcherType.REQUEST})
public class FilterDemo5 implements Filter {

    /**
     * Default constructor.
     */
    public FilterDemo5() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Filter#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("FilterDemo5...");
        chain.doFilter(request, response);
    }

    /**
     * @see Filter#init(FilterConfig)
     */
    public void init(FilterConfig fConfig) throws ServletException {
        // TODO Auto-generated method stub
    }

}

package cn.itcast.web.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class ServletDemo2
 */
@WebServlet("/user/updateServlet")
public class ServletDemo2 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ServletDemo2() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("updateServlet...");
        //转发到index.jsp
        request.getRequestDispatcher("../index.jsp").forward(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
  <display-name>day19</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <filter>
      <filter-name>demo5</filter-name>
      <filter-class>cn.itcast.web.filter.FilterDemo5</filter-class>
  </filter>
  <filter-mapping>
      <filter-name>demo5</filter-name>
      <url-pattern>/*</url-pattern>
      <dispatcher>REQUEST</dispatcher>
      <dispatcher>FORWARD</dispatcher>
  </filter-mapping>
</web-app>