servlet过滤器

来源：互联网发布：打口碟淘宝编辑：程序博客网时间：2024/06/05 21:04

servlet过滤器能够对servlet容器的请求和响应对象进行检查和修改

servlet过滤器本身并不生成请求和响应对象，它只提供过滤作用

servlet过滤器能够在servlet被调用之前检查request对象，修改request header和request内容
servlet过滤器能够在servlet被调用之前检查response对象，修改response header和response内容

servlet过滤器负责过滤的wrb组件可能是servlet，jsp或html文件

这里写图片描述

login的主页面

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>  </head>  <body>    <form action="/test/userloginservlet" method="post">      username：<input type="text" name="username"><br>      password:<input type="password" name="password"><br>      authority:      <select name="authority">       <option value="1">common user</option>       <option value="2">administrator</option>      </select>      <br>      <input type="submit" value="submit">    </form>  </body></html>

用户登录成功的主界面

<%@ page language="java" import="com.hpu.javabean.User" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">    <title>My JSP 'index.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache">    <meta http-equiv="cache-control" content="no-cache">    <meta http-equiv="expires" content="0">        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">    <meta http-equiv="description" content="This is my page">    <!--    <link rel="stylesheet" type="text/css" href="styles.css">    -->  </head>  <body>    <a herf="QueryServlet">query</a><br>    <%if(((User)session.getAttribute("user")).getAuthority().equals("2")){%>    <a herf="UpdateServlet">update</a>  </body>  <%} %></html>

登录成功之后主页面

<%@ page language="java" import="com.hpu.javabean.User" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">    <title>My JSP 'index.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache">    <meta http-equiv="cache-control" content="no-cache">    <meta http-equiv="expires" content="0">        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">    <meta http-equiv="description" content="This is my page">    <!--    <link rel="stylesheet" type="text/css" href="styles.css">    -->  </head>  <body>    <a herf="QueryServlet">query</a><br>    <%if(((User)session.getAttribute("user")).getAuthority().equals("2")){%>    <a herf="UpdateServlet">update</a>  </body>  <%} %></html>

filter的代码

package com.hpu.filter;import java.io.IOException;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.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.omg.CORBA.Request;public class loginfilter implements Filter{    public void destroy()    {        // TODO Auto-generated method stub    }    public void doFilter(ServletRequest request, ServletResponse response,            FilterChain chain) throws IOException, ServletException    {        HttpServletRequest r = (HttpServletRequest)request;        String requestURI = r.getRequestURI();        if(requestURI.endsWith("UserLogin.jsp")||requestURI.endsWith("QueryServlet"))        {            chain.doFilter(request, response);            return;        }        HttpSession session=r.getSession();        if(null == session.getAttribute("user"))        {            ((HttpServletResponse)response).sendRedirect("/UserLogin.jsp");            return;        }        else        {            chain.doFilter(request, response);        }        System.out.println("doFilter invoked!");    }    public void init(FilterConfig arg0) throws ServletException    {        System.out.println("init invoked");    }}

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