Cookie实现十天内免登录

• 代码：

   - CheckLogin 查看是否获取到了Cookie，如果获取到了连接数据库验证Cookie发过来的用户名和密码，如果没有获取到Cookie信息，那么就跳转到登录页
    
      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 java.io.IOException;
      import java.io.PrintWriter;
      import java.sql.*;

      public class CheckLogin extends HttpServlet {
          @Override
          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


                   //定义需要的变量
                   String userEmail=null;
                   String userPwd=null;
                   String userName=null;
                   boolean loginFlag=false;

                  //获取浏览器提交给服务器的Cookie信息
                    Cookie[] cookies=request.getCookies();

                  //遍历Cookie数组
                   if(cookies!=null){
                       for (Cookie cookie:cookies) {
                           String cookieName=cookie.getName();
                           String cookieValue=cookie.getValue();
                           if(cookieName.equals("userEmail")){
                               userEmail=cookieValue;
                               System.out.println(userEmail);
                           }else if(cookieName.equals("userPwd")){
                               userPwd=cookieValue;
                               System.out.println(userPwd);
                           }
                       }
                   }else{
                       response.sendRedirect("/myWeb/login.html");

                   }

            if(userEmail!=null && userPwd!=null) {
                //创建数据库连接对象
                Connection connection = null;
                PreparedStatement preparedStatement = null;
                ResultSet resultSet = null;

                try {

                    // 连接数据库
                    Class.forName("com.mysql.cj.jdbc.Driver");

                    // 获取连接
                    connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai",
                            "root", "123456");

                    // 获取预编译数据库操作对象
                    String sql = "select username,email,userpwd from t_userInfo where email=? and userpwd=?";
                    preparedStatement = connection.prepareStatement(sql);

                    //给预编译语句传参
                    preparedStatement.setString(1, userEmail);
                    preparedStatement.setString(2, userPwd);

                    //执行SQL语句
                    resultSet = preparedStatement.executeQuery();

                    //处理查询结果集
                    while (resultSet.next()) {
                        loginFlag = true;
                        userName = resultSet.getString("username");
                    }
                } catch (ClassNotFoundException | SQLException e) {
                    e.printStackTrace();
                } finally {

                    //释放资源
                    if (resultSet != null) {
                        try {
                            resultSet.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
                    if (preparedStatement != null) {
                        try {
                            preparedStatement.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }

                    if (connection != null) {
                        try {
                            connection.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
                    //设置字符集，获取字符输入流
                    response.setContentType("text/html;charset=UTF-8");
                    PrintWriter out = response.getWriter();
                    if (loginFlag) {
                        //验证Cookie发过来的邮箱密码都正确
                        //HTML代码
                        out.print("          <!DOCTYPE html>");
                        out.print("<meta http-equiv=\"content-type\" content=\"text/html\" charset=\"utf-8\"/> ");
                        out.print("  <head>");
                        out.print("      <meta charset='UTF-8'>");
                        out.print("      <title>用户信息</title>");
                        out.print("  </head>");
                        out.print("     <body>");
                        out.print("          <h3 align='center'>登陆成功，欢迎" + userName + "</h3>");
                        out.print("    </body>");
                        out.print("  </html>");
                    } else {

                        //登录失败
                        //HTML代码
                        out.print("          <!DOCTYPE html>");
                        out.print("<meta http-equiv=\"content-type\" content=\"text/html\" charset=\"utf-8\"/> ");
                        out.print("  <head>");
                        out.print("      <meta charset='UTF-8'>");
                        out.print("      <title>用户信息</title>");
                        out.print("  </head>");
                        out.print("     <body>");
                        out.print("          <h3 align='center'>密码错误，请重试");
                        out.print("         <a href='/myWeb/login.html'>重新登录</a>");
                        out.print("    </body>");
                        out.print("  </html>");

                    }
                }
            }else{
                response.sendRedirect("/myWeb/login.html");
            }
          }

      }

• 登录页， 获取用户在表单中输入的用户名和密码，连接数据库验证用户名和密码， 验证用户名和密码正确的话，继续验证用户是否勾选了免登录的复选框，如果勾选了，创建cookie，并将cookie发送给浏览器。

             package com.shige.controller;
  
        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 java.io.IOException;
        import java.io.PrintWriter;
        import java.sql.*;
  
        public class LoginServlet extends HttpServlet {
            @Override
            protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
                //解决中文乱码问题
                request.setCharacterEncoding("UTF-8");
  
                //获取用户提交的表单数据
                  String userEmail=request.getParameter("email");
                  String userPwd=request.getParameter("password");
                //创建数据库连接对象
                Connection connection=null;
                PreparedStatement preparedStatement=null;
                ResultSet resultSet=null;
                boolean loginFlag=false;
                String userName=null;
  
  
                try {
  
                    // 连接数据库
                    Class.forName("com.mysql.cj.jdbc.Driver");
  
                    // 获取连接
                    connection= DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai",
                            "root","123456");
  
                    // 获取预编译数据库操作对象
                    String sql="select username,email,userpwd from t_userInfo where email=? and userpwd=?";
                    preparedStatement=connection.prepareStatement(sql);
  
                    //给预编译语句传参
                    preparedStatement.setString(1,userEmail);
                    preparedStatement.setString(2,userPwd);
  
                    //执行SQL语句
                    resultSet=preparedStatement.executeQuery();
  
                    //处理查询结果集
  
                    while(resultSet.next()){
                        loginFlag=true;
                        userName=resultSet.getString("username");
                    }
  
                  } catch (ClassNotFoundException | SQLException e) {
                    e.printStackTrace();
                }finally {
  
                    //释放资源
                    if(resultSet!=null){
                        try {
                            resultSet.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
                    if(preparedStatement!=null){
                        try {
                            preparedStatement.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
  
                    if(connection!=null){
                        try {
                            connection.close();
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                    }
  
                    if(loginFlag){
                      //登录成功
                        //登录成功够查看用户是否选择了自动登录的按钮
                        String tenDayAutoLogin=request.getParameter("tenDayAutoLogin");
                        System.out.println(tenDayAutoLogin);
                        if("ok".equals(tenDayAutoLogin)){
                            //说明用户勾选了十天内免登录的选项
                              //创建Cookie对象
                            Cookie cookie1=new Cookie("userEmail",userEmail);
                            Cookie cookie2=new Cookie("userPwd",userPwd);
  
                              //设置Cookie有效时间
                            cookie1.setMaxAge(60*60*24*10);
                            cookie2.setMaxAge(60*60*24*10);
  
                              //设置Cookie关联路径
                            cookie1.setPath(request.getContextPath());
                            cookie2.setPath(request.getContextPath());
  
                              //将Cookie对象发送给浏览器
                            response.addCookie(cookie1);
                            response.addCookie(cookie2);
                        }
                        response.setContentType("text/html;charset=UTF-8");
                        PrintWriter out=response.getWriter();
                        //HTML代码
                        out.print("          <!DOCTYPE html>");
                        out.print("<meta http-equiv=\"content-type\" content=\"text/html\" charset=\"utf-8\"/> ");
                        out.print("  <head>");
                        out.print("      <meta charset='UTF-8'>");
                        out.print("      <title>用户信息</title>");
                        out.print("  </head>");
                        out.print("     <body>");
                        out.print("          <h3 align='center'>登陆成功，欢迎"+userName+"</h3>");
                        out.print("    </body>");
                        out.print("  </html>");
                    }else{
                        response.setContentType("text/html;charset=UTF-8");
                        PrintWriter out=response.getWriter();
                        //登录失败
                        //HTML代码
                        out.print("          <!DOCTYPE html>");
                        out.print("<meta http-equiv=\"content-type\" content=\"text/html\" charset=\"utf-8\"/> ");
                        out.print("  <head>");
                        out.print("      <meta charset='UTF-8'>");
                        out.print("      <title>用户信息</title>");
                        out.print("  </head>");
                        out.print("     <body>");
                        out.print("          <h3 align='center'>密码错误，请重试");
                        out.print("         <a href='/myWeb/login.html'>重新登录</a>");
                        out.print("    </body>");
                        out.print("  </html>");
  
                    }
                }
  
  
            }
        }