cookies session filter 自动登录

webxml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">

  <display-name></display-name>

  <servlet>

    <servlet-name>LoginServlet</servlet-name>

    <servlet-class>com.itheima.web.servlet.LoginServlet</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>LoginServlet</servlet-name>

    <url-pattern>/servlet/LoginServlet</url-pattern>

  </servlet-mapping>

  <welcome-file-list>

    <welcome-file>index.jsp</welcome-file>

  </welcome-file-list>

  <filter>

    <display-name>CharacterEncodingFilter</display-name>

    <filter-name>CharacterEncodingFilter</filter-name>

    <filter-class>com.itheima.web.filter.CharacterEncodingFilter</filter-class>

  </filter>

  <filter-mapping>

    <filter-name>CharacterEncodingFilter</filter-name>

    <url-pattern>/*</url-pattern>

  </filter-mapping>

  <filter>

    <display-name>AutoLoginFilter</display-name>

    <filter-name>AutoLoginFilter</filter-name>

    <filter-class>com.itheima.web.filter.AutoLoginFilter</filter-class>

  </filter>

  <filter-mapping>

    <filter-name>AutoLoginFilter</filter-name>

    <url-pattern>*.jsp</url-pattern>

  </filter-mapping>

</web-app>

domain 实体

package com.itheima.domain;

import java.io.Serializable;

public class User implements Serializable {

    private String username;

    private String password;

    public User(String username, String password) {

        super();

        this.username = username;

        this.password = password;

    }

    public User() {

        super();

    }

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public String getPassword() {

        return password;

    }

    public void setPassword(String password) {

        this.password = password;

    }

}

模仿的数据库连接

package com.itheima.domain;

import java.util.ArrayList;

import java.util.List;

public class UserDB {

    private static List<User> users = new ArrayList<User>();

    static{

        users.add(new User("陈尧","123"));

        users.add(new User("李春鹏","123"));

        users.add(new User("凤姐","123"));

    }

    public static User findUser(String username,String password){

        for(User u:users){

            if(username.equals(u.getUsername())&&password.equals(u.getPassword())){

                return u;

            }

        }

        return null;

    }

    public static User findUser(String username){

        for(User u:users){

            if(username.equals(u.getUsername())){

                return u;

            }

        }

        return null;

    }

}

工具类

package com.itheima.utils;

import java.io.IOException;

import org.junit.Test;

import com.sun.org.apache.xml.internal.security.exceptions.Base64DecodingException;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;

public class Base64Util {

    //编码    中文 -------------5Lit5paH

    public static String encode(String str){

        BASE64Encoder b64= new BASE64Encoder();

        return b64.encode(str.getBytes());

    }

    //解码   5Lit5paH----中文

    public static String decode(String str){

        try {

            BASE64Decoder b64decoder = new BASE64Decoder();

            byte [] afterStr = b64decoder.decodeBuffer(str);

            return new String(afterStr);

        } catch (IOException e) {

            e.printStackTrace();

            throw new RuntimeException(e);

        }

    }

    @Test

    public void testEncode(){

        String str = Base64Util.encode("中文");

        System.out.println(str);

        String newString = Base64Util.decode(str);

        System.out.println(newString);

    }

}

md5

package com.itheima.utils;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import sun.misc.BASE64Encoder;

public class Md5Util {

    //md5加密的方法

    public static String encode(String old){

        try {

            MessageDigest md5 = MessageDigest.getInstance("md5");

            byte newStr[] = md5.digest(old.getBytes());

            BASE64Encoder b64= new BASE64Encoder();

            return b64.encode(newStr);

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

            throw new RuntimeException(e);

        }

    }

}

filter

package com.itheima.web.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 com.itheima.domain.User;

import com.itheima.domain.UserDB;

import com.itheima.utils.Base64Util;

import com.itheima.utils.Md5Util;

/**

 *过滤器，用于实现自动登录过滤

 */

public class AutoLoginFilter implements Filter {

    public void destroy() {

    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;

        HttpServletResponse response = (HttpServletResponse) resp;

        //1.如果是进行登录操作，直接放行

        String resource = request.getRequestURI();//得到资源名

        boolean isLogin = resource.endsWith("login.jsp");//判断是否想进行登录操作

        if(!isLogin){

            //不是登录才处理

            //2.不是做登录操作，是否已登录过？？？

            User user= (User)request.getSession().getAttribute("user");

            if(user==null){

                // 说明之前也没有登录过

                //3.就要读取Cookie并进行用户名密码的验证

                //3.1如何读cookie

                Cookie []cookies = request.getCookies();

                if(cookies==null || cookies.length==0){

                    response.sendRedirect(request.getContextPath()+"/login.jsp");//cookie中没有保存之前的登录信息，就要重新登录

                    return;

                }

                Cookie myCookie =null;

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

                    Cookie c = cookies[i];//找一个cookie

                    if("loginedUser".equals(c.getName())){

                        //找到你想要的登录信息的cookie

                        myCookie = c;

                        break;

                    }

                }

                //判断myCookie是否为空，如果不为空，说明找到登录过的用户信息的Cookie

                if(myCookie!=null){

                    String usernameAndpassword = myCookie.getValue();//base64username_md5password

                    String username = usernameAndpassword.split("_")[0];//得到用户名

                    String password= usernameAndpassword.split("_")[1];//得到密码

                    //得到解码后用户名

                    username = Base64Util.decode(username);

                    //根据用户名，判断该用户在数据库中是否存在

                    User u = UserDB.findUser(username);

                    if(u!=null  && password.equals(Md5Util.encode(u.getPassword()))){

                        //你没登录，我自动给你登录了

                        request.getSession().setAttribute("user", u);

                    }

                }

            }

        }

        chain.doFilter(request, response);

    }

    public void init(FilterConfig fConfig) throws ServletException {

        // TODO Auto-generated method stub

    }

}

编码filter

package com.itheima.web.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;

/**

 * Servlet Filter implementation class CharacterEncodingFilter

 */

public class CharacterEncodingFilter implements Filter {

    public void destroy() {

    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

        request.setCharacterEncoding("UTF-8");//post乱码

        response.setContentType("text/html;charset=UTF-8");//响应时没有乱码

        chain.doFilter(request, response);

    }

    public void init(FilterConfig fConfig) throws ServletException {

    }

}

sevlet

package com.itheima.web.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;

import com.itheima.domain.User;

import com.itheima.domain.UserDB;

import com.itheima.utils.Base64Util;

import com.itheima.utils.Md5Util;

/**

 * 登录

 * @author wangli

 *

 */

public class LoginServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        //1.可能有乱码（不关注 ，因为过滤器已解决了）

        //2.获取参数

        String username = request.getParameter("username");

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

        String expires = request.getParameter("expires");

        //3.判断用户名密码有效性

        User u = UserDB.findUser(username, password);

        if(u==null){

            //登录失败

            response.setHeader("Refresh", "2;URL="+request.getContextPath()+"/login.jsp");

            response.getWriter().write("对不起，登录失败，2秒后跳到登录页");

            return ;

        }

        //4.如果正确，将用户信息存入Session

        request.getSession().setAttribute("user", u);

        //5.判断是否要保存一段 时间，如果是要存储  （存什么？   用户名（编码）_密码（加密））

        Cookie c  = new Cookie("loginedUser",Base64Util.encode(username)+"_"+Md5Util.encode(password));//数据库UserDb中有中文 ，而cookie文件中不能有中文

        //中文 可以先进行编码   ，当要使用中文时，又进行解码

        //6.设置cookie的有效期

        if("never".equals(expires)){

            c.setMaxAge(0);

        }else if("month".equals(expires)){

            c.setMaxAge(30*24*60*60);  //cookie存活时间 的单位：秒

        }else if("year".equals(expires)){

            c.setMaxAge(365*24*60*60);

        }else if("forever".equals(expires)){

            c.setMaxAge(Integer.MAX_VALUE);

        }

        c.setPath(request.getContextPath());

        //7.将cookie信息发送给浏览器

        response.addCookie(c);

        //8.进入主页面

        response.setHeader("Refresh", "2;URL="+request.getContextPath()+"/index.jsp");

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        this.doGet(request, response);

    }

}

jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title>XX网站</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">

    -->

    <%

            //读取cookie

     %>

  </head>

  <body>

          <c:if test="${sessionScope.user==null}">

              <a href="${pageContext.request.contextPath}/login.jsp">登录</a>

          </c:if>

          <c:if test="${sessionScope.user!=null}">

              欢迎您：${user.username}<a href="#">注销</a>

          </c:if>

          <hr/>

          XX网站

          <a href="${pageContext.request.contextPath}/bbs.jsp">帖子</a>

  </body>

</html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title></title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

  </head>

  <body>

    <form action="${pageContext.request.contextPath}/servlet/LoginServlet" method="post">

        用户名：<input type="text" name="username"/><br/>

        密码：<input type="password" name="password"/><br/>

        登录有效期：<input type="radio" name="expires" value="never" checked="checked">无

                <input type="radio" name="expires" value="month">一个月

                <input type="radio" name="expires" value="year">一年

                <input type="radio" name="expires" value="forever">永久<br/>

        <input type="submit" value="登录"/>

    </form>

  </body>

</html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title></title>

    <meta http-equiv="pragma" content="no-cache">

    <meta http-equiv="cache-control" content="no-cache">

    <meta http-equiv="expires" content="0">

    <%

            //读取cookie

     %>

  </head>

  <body>

    ${sessionScope.user.username}

  </body>

</html>