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>