学步园

package cn.itcast.util;

import java.io.IOException;

import java.io.PrintWriter;

import java.io.UnsupportedEncodingException;

import javax.servlet.FilterChain;

import javax.servlet.ServletException;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import cn.itcast.bean.User;

import cn.itcast.dao.UserDAO;

import cn.itcast.factory.DaoImplFactory;

import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;

/*

* 2007.09.21 by lyhapple

* */

public class CookieUtil {

       //保存cookie时的cookieName

       private final static String cookieDomainName = “cn.itcast”;

      

       //加密cookie时的网站自定码

       private final static String webKey = “itcast”;

      

//设置cookie有效期是两个星期，根据需要自定义

       private final static long cookieMaxAge = 60 * 60 * 24 * 7 * 2;

      

       //保存Cookie到客户端--------------------------------------------------------------------------------------------------------

       //在CheckLogonServlet.java中被调用

       //传递进来的user对象中封装了在登陆时填写的用户名与密码

       public static void saveCookie(User user, HttpServletResponse response) {

             

              //cookie的有效期

              long validTime = System.currentTimeMillis() + (cookieMaxAge * 1000);

             

              //MD5加密用户详细信息

              String cookieValueWithMd5 =getMD5(user.getUserName() + ":" + user.getPassword()

                            + ":" + validTime + ":" + webKey);

             

              //将要被保存的完整的Cookie值

              String cookieValue = user.getUserName() + ":" + validTime + ":" + cookieValueWithMd5;

             

              //再一次对Cookie的值进行BASE64编码

              String cookieValueBase64 = new String(Base64.encode(cookieValue.getBytes()));

             

              //开始保存Cookie

              Cookie cookie = new Cookie(cookieDomainName, cookieValueBase64);

              //存两年(这个值应该大于或等于validTime)

cookie.setMaxAge(60 * 60 * 24 * 365 * 2);

//cookie有效路径是网站根目录

              cookie.setPath("/");

              //向客户端写入

              response.addCookie(cookie);

       }

      

       //读取Cookie,自动完成登陆操作--------------------------------------------------------------------------------------------

       //在Filter程序中调用该方法,见AutoLogonFilter.java

       public static void readCookieAndLogon(HttpServletRequest request, HttpServletResponse response,

FilterChain chain) throws IOException, ServletException,UnsupportedEncodingException{

                    

//根据cookieName取cookieValue

Cookie cookies[] = request.getCookies();

                     String cookieValue = null;

                     if(cookies!=null){

                            for(int i=0;i

                                   if (cookieDomainName.equals(cookies[i].getName())) {

                                          cookieValue = cookies[i].getValue();

                                          break;

                                   }

                            }

                     }

                     //如果cookieValue为空,返回,

                     if(cookieValue==null){

                            return;

                     }

             

              //如果cookieValue不为空,才执行下面的代码

              //先得到的CookieValue进行Base64解码

              String cookieValueAfterDecode = new String (Base64.decode(cookieValue),"utf-8");

             

              //对解码后的值进行分拆,得到一个数组,如果数组长度不为3,就是非法登陆

              String cookieValues[] = cookieValueAfterDecode.split(":");

              if(cookieValues.length!=3){

                     response.setContentType("text/html;charset=utf-8");

                     PrintWriter out = response.getWriter();

                     out.println("你正在用非正常方式进入本站...");

                     out.close();

                     return;

              }

             

              //判断是否在有效期内,过期就删除Cookie

              long validTimeInCookie = new Long(cookieValues[1]);

              if(validTimeInCookie < System.currentTimeMillis()){

                     //删除Cookie

                     clearCookie(response);

                     response.setContentType("text/html;charset=utf-8");

                     PrintWriter out = response.getWriter();

                     out.println("");你的Cookie已经失效,请重新登陆

                     out.close();

                     return;

              }

             

              //取出cookie中的用户名,并到数据库中检查这个用户名,

              String username = cookieValues[0];

             

              //根据用户名到数据库中检查用户是否存在

              UserDAO ud = DaoImplFactory.getInstance();

              User user = ud.selectUserByUsername(username);

             

              //如果user返回不为空,就取出密码,使用用户名+密码+有效时间+ webSiteKey进行MD5加密

              if(user!=null){

                     String md5ValueInCookie = cookieValues[2];

                     String md5ValueFromUser =getMD5(user.getUserName() + ":" + user.getPassword()

                                   + ":" + validTimeInCookie + ":" + webKey);

                     //将结果与Cookie中的MD5码相比较,如果相同,写入Session,自动登陆成功,并继续用户请求

                     if(md5ValueFromUser.equals(md5ValueInCookie)){

                            HttpSession session = request.getSession(true);

                            session.setAttribute("user", user);

                            chain.doFilter(request, response);

                     }

              }else{

       //返回为空执行

                     response.setContentType("text/html;charset=utf-8");

                     PrintWriter out = response.getWriter();

                     out.println("cookie验证错误！");

                     out.close();

       return;

}

       }

      

       //用户注销时,清除Cookie,在需要时可随时调用------------------------------------------------------------

       public static void clearCookie( HttpServletResponse response){

              Cookie cookie = new Cookie(cookieDomainName, null);

              cookie.setMaxAge(0);

              cookie.setPath("/");

              response.addCookie(cookie);

       }

//获取Cookie组合字符串的MD5码的字符串----------------------------------------------------------------------------

              public static String getMD5(String value) {

                     String result = null;

                     try{

                            byte[] valueByte = value.getBytes();

                            MessageDigest md = MessageDigest.getInstance("MD5");

                            md.update(valueByte);

                            result = toHex(md.digest());

                     } catch (NoSuchAlgorithmException e2){

                            e1.printStackTrace();

}

                     return result;

              }

      

//将传递进来的字节数组转换成十六进制的字符串形式并返回

              private static String toHex(byte[] buffer){

                     StringBuffer sb = new StringBuffer(buffer.length * 2);

                     for (int i = 0; i < buffer.length; i++){

                            sb.append(Character.forDigit((buffer[i] & 0xf0) >> 4, 16));

                            sb.append(Character.forDigit(buffer[i] & 0x0f, 16));

                     }

                     return sb.toString();

              }

}

转自http://aaagu1234.blog.163.com/blog/static/4009371520109221265426/