cook的使用（两星期自动登录）
//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＜cookies.length; 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("＜a href=’logon.jsp’>你的Cookie已经失效,请重新登陆＜/a>");
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();
}
}
下面的是对CookieUtil工具类各方法的调用演示：
User.java
封装用户信息的JavaBean对象模型
package com.itcast.bean;
public class User {
private int id;
private String userName;
private String password;
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
}
AutoLogonFilter.java
过滤器程序,可在WEB-INF/web.xml中设置过滤规则,本文对过滤规则不作介绍，此程序主要作用是检查用户在上一次登陆时是否保存了Cookie，如果保存了，就处理Cookie信息，并帮助用户自动登陆
本程序主要调用了CookieUtil.java中的读取与自动登陆方法，即readCookieAndLogon方法
package cn.itcast.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;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.itcast bean.User;
import cn.itcast.util.CookieUtil;
public class AutoLogonFilter implements Filter {
public void destroy() {
}
//保存cookie时的cookieName,与CookieUtil.java中的设置相同
private final static String cookieDomainName = “cn.itcast”;
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)resp;
HttpSession session = request.getSession(true);
User user = (User)session.getAttribute("user");
//如果封装的user不为空,说明已经登陆,则继续执行用户的请求.下面的就不处理了
if(user!=null){
chain.doFilter(request,response);
return;
}
//user为空，说明用户还没有登陆,就尝试得到浏览器传送过来的Cookie
Cookie cookies[] = request.getCookies();
String cookieValue = null;
if(cookies!=null){
for(int i=0; i＜cookies.length; i++){
if (cookieDomainName.equals(cookies[i].getName())) {
cookieValue = cookies[i].getValue();
break;
}
}
}
//如果cookieValue为空,也继续执行用户请求
if(cookieValue==null){
chain.doFilter(request,response);
return;
}
//cookieValue不为空执行下面的方法,调用CookieUtil.java中的readCookieAndLogon方法
try{
CookieUtil.readCookieAndLogon(cookieValue, request, response, chain);
}catch(Exception e){
e.printStackTrace();
}
}
public void init(FilterConfig arg0) throws ServletException {
}
}
CheckLogonServlet.java
验证用户登陆信息的Servlet，此程序调用了CookieUtil.java中的saveCookie方法
package cn.itcast.servlet;
/*
* update 2007.09.23 by lyhapple
* 检查用户登陆
* */
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.itcast.bean.User;
import cn.itcast.dao.UserDAO;
import cn.itcast.factory.DaoImplFactory;
import cn.itcast.util.CookieUtil;
public class CheckLogonServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
String username = request.getParameter("username").trim();
String password = CookieUtil.getMD5(request.getParameter("password"));
String remeberMe = request.getParameter("remeberMe");
HttpSession session = request.getSession(false);
// 将接收到的用户名传递到UserDao的checkUser方法中,检查用户
// 返回一个User类型的对象
UserDAO ud = DaoImplFactory.getInstance();
User user = ud.selectUserByUsername(username);
if (user == null) {
request.setAttribute("checkUserError","＜a href='register.jsp'>＜font color=red>用户名不存在,请先注册＜/font>＜/a>");
request.getRequestDispatcher("index.jsp").forward(request, response);
return;
}
if(!password.equals(user.getPassword())){
request.setAttribute("checkPasswordError","＜font color=red>密码输入错误,请重新输入＜/font>");
request.getRequestDispatcher("index.jsp").forward(request, response);
return;
}
//保存Cookie,这里调用了CookieUtil.java中的saveCookie方法，将上面的user对象作为参数传递
if ("on".equals(remeberMe)) {
CookieUtil.saveCookie(user, response);
}
//在Session中保存用户信息，并转向用户的个人信息页面
session.setAttribute("user", user);
request.getRequestDispatcher("User/userInfo.jsp").forward(request,response);
}
}
UserDAO.java与DaoImplFactory.java属于持久层相关的程序，这里就不贴出来了，读者可根据自己需要选择不同的持久层框架，在本程序中只要实现查询用户的功能就可以了
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