关于servlet中Filter的使用 -

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关于servlet中Filter的使用

博客分类：

java
servlet
jsp

 用户登录功能的实现，非法用户不能访问指定资源

代码结构如下：

UserInfo.java代码如下：

package com.bean;

public class UserInfo {
	
	private String name ;
	
	private String password;
	
	public UserInfo(){
		
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}
	
}

FilterStation.java

package com.filter;

import java.io.IOException;
import java.io.PrintWriter;

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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

public class FilterStation extends HttpServlet implements Filter{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		HttpSession session = ((HttpServletRequest)request).getSession();
		 response.setCharacterEncoding("utf-8");
		if(session.getAttribute("user")==null){
			PrintWriter out = response.getWriter();
			out.print("<script language=javascript>alert('you do not login!');window.location.href='../index.jsp';</script>");
		}else{
			chain.doFilter(request, response);
		}
	}

	public void init(FilterConfig config) throws ServletException {
		
	}

}

web.xml代码如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	<filter>
		<filter-name>filterstation</filter-name>
		<filter-class>com.filter.FilterStation</filter-class>
	</filter>
	<filter-mapping>
	 <filter-name>filterstation</filter-name>
	 <url-pattern>/jsp/*</url-pattern>
	</filter-mapping>
</web-app>

index.jsp代码如下：

<%@ 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>
		<base href="<%=basePath%>">

		<title>login</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">
	</head>

	<body>
		<form name="form1" method="post" action="result.jsp">
			<table width="233" border="1" cellpadding="0" cellspacing="0">
				<tr align="center">
					<td width="48" height="30">
						账号
					</td>
					<td width="179">
						<input type="text" name="account">
					</td>
				</tr>
				<tr align="center">
					<td height="30">
						密码
					</td>
					<td>
						<input type="password" name="password">
					</td>
				</tr>
			</table>
			<input type="submit" name="Submit" value="提交" />
		</form>
	</body>
</html>

result.jsp代码如下：

<%@ page import="com.bean.UserInfo"%>
<%
	request.setCharacterEncoding("utf-8");
	String name = request.getParameter("name");
	String password = request.getParameter("password");
	UserInfo user = new UserInfo();
	user.setName(name);
	user.setPassword(password);
	session.setAttribute("user", user);
	response.sendRedirect("jsp/showInformation.jsp");
%>

back.jsp代码如下：

<% 
 session.invalidate();
out.print("<script language='javascript'> window.location.href='../index.jsp';</script>");
%>

showInformation.jsp代码如下：

<%@ 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>
    <base href="<%=basePath%>">
    
    <title>show information</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">
  </head>
  
  <body>
     <script language="javascript">
      window.alert('您登录成功');
      window.location.href="jsp/back.jsp";
     </script>
  </body>
</html>

运行结果：
合法用户登录