java中cookie的操作（通过cookie实现简单的单点登录）

java中cookie的操作（通过cookie实现简单的单点登录）

 

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（一）取得cookie中的相关信息
Cookie[] cookies = request.getCookies();

            String username = "";
            String password = "";

            if (cookies != null) {
                for (int i = 0; i < cookies.length; i++) {
                    Cookie c = cookies[i];

                    if (c.getName().equalsIgnoreCase("xabpoUsername")) {
                        username = c.getValue();
                    } else if (c.getName().equalsIgnoreCase("xabpoPassword")) {
                        password = c.getValue();
                    }
                }
            }
（二）将登陆用户的用户名和密码保存到cookie中
            Cookie cookieUsername = new Cookie("xabpoUsername",userForm.getUserID());
            Cookie cookiePassword = new Cookie("xabpoPassword",userForm.getPassword())                   cookieUsername.setMaxAge(60*60*24); //设定有效时间
            cookiePassword.setMaxAge(60*60*24);
            cookieUsername.setPath("/");
            cookiePassword.setPath("/");
            cookieUsername.setDomain(".xasourcing.gov.cn"); // 设定有效域
            cookiePassword.setDomain(".xasourcing.gov.cn");
            response.addCookie(cookieUsername);
            response.addCookie(cookiePassword);
（三）退出登录的时候将cookie删除
Cookie[] cookies=request.getCookies();
        try
        {
            if (cookies != null) {
                for (int i = 0; i < cookies.length; i++) {

                    String cookieName = cookies[i].getName();
                    if (cookieName.equals("xabpoUsername")
                            || cookieName.equals("xabpoPassword")) {
                        cookies[i].setValue(null);
                        cookies[i].setPath("/");
                        cookies[i].setMaxAge(0);
                        response.addCookie(cookies[i]);
                    }
                }
            }
        }catch(Exception e)
        {
            LogUtil.error(this.getClass(), e.getMessage(), e);
        }
删除的时候上面标红的几段比较重要
（1）设为null这句如果没有的话，如果你退出登录的逻辑后紧跟着一个从cookie中取值的操作，这时就
能从cookie中取到删除过的值。
（2）cookies[i].setPath("/");这句，如果不和设定cookie的时候的path不对应起来，就有删不掉cookie的可能。
（3）cookies[i].setMaxAge(0);这个就是设定该cookie立马过期的操作。

三个文件：

一个过滤器：

package com.njupt.sso.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.Cookie;
import javax.servlet.http.HttpServletRequest;


public class AutoLoginFilter implements Filter {


@Override
public void destroy() {


}


@Override
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;

if(request.getSession().getAttribute("user")== null){
Cookie[] cs = request.getCookies();


if (cs != null && cs.length > 0) {
for (Cookie c : cs) {
String cName = c.getName();
if (cName.equals("sso")) {
String userName = c.getValue();
request.getSession().setAttribute("user", userName);
}
}
}
}


chain.doFilter(request, resp);


}


@Override
public void init(FilterConfig arg0) throws ServletException {


}


}

一个登陆文件

package com.njupt.sso.servlet;


import java.io.IOException;


import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class LoginServlet extends HttpServlet {


/**
* Constructor of the object.
*/
public LoginServlet() {
super();
}


/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}


/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
* 
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {


this.doPost(request, response);
}


/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
* 
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {


String userName = request.getParameter("userName");
String password = request.getParameter("password");

if(userName != null && password != null){
if(userName.equals(password)){//登录成功，实际应查询数据库
request.getSession().setAttribute("user", userName);

//向客户端写入cookie
Cookie c = new Cookie("sso",userName);

c.setMaxAge(3600);//1小时
c.setDomain(".njupt.com");//www.bbs.njupt.com www.news.njupt.com
c.setPath("/");

response.addCookie(c);
}
}

response.sendRedirect(request.getContextPath() + "/index.jsp");
}


/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}


}

一个web.xml文件

<?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">
  
  <filter>
<filter-name>autoLogin</filter-name>
<filter-class>com.njupt.sso.filter.AutoLoginFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>autoLogin</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
  
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>com.njupt.sso.servlet.LoginServlet</servlet-class>
  </servlet>


  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

主页index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="c"  uri="http://java.sun.com/jsp/jstl/core"%>
<%
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> 
    <c:choose>
   <c:when test="${not empty sessionScope.user}">
    欢迎你：${sessionScope.user}
    </c:when>
    <c:otherwise>
    你还没有登录，请先登录：
    <form action="<%=path %>/login" method="post">
    userName:<input type="text" name="userName"><br>
    password:<input type="password" name="password"><br>
    <input type="submit" value="登录">
    </form>
    </c:otherwise>
  </c:choose>
  </body>
</html>