Session实现验证码登陆笔记

1.生成验证码Servlet

 package com.isit.servlet;

 import javax.imageio.ImageIO;
 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 import java.awt.*;
 import java.awt.image.BufferedImage;
 import java.io.IOException;
 import java.util.Random;

 @WebServlet("/checkCodeServlet")
 public class CheckCodeServlet extends HttpServlet {
     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

         int width = 100;
         int height = 50;

         //1.创建一对象，在内存中图片(验证码图片对象)
         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

         //2.美化图片
         //2.1 填充背景色
         Graphics g = image.getGraphics();//画笔对象
         g.setColor(Color.PINK);//设置画笔颜色
         g.fillRect(0, 0, width, height);

         //2.2画边框
         g.setColor(Color.BLUE);
         g.drawRect(0, 0, width - 1, height - 1);

         String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
         //生成随机角标
         StringBuffer sb = new StringBuffer();
         Random ran = new Random();
         for (int i = 1; i <= 4; i++) {
             int index = ran.nextInt(str.length());
             //获取字符
             char ch = str.charAt(index);//随机字符
             sb.append(ch);
             //2.3写验证码
             g.drawString(ch + "", width / 5 * i, height / 2);
         }
         String checkCode = sb.toString();
         HttpSession session = request.getSession();
         session.setAttribute("checkCode", checkCode);
         //2.4画干扰线
         g.setColor(Color.GREEN);

         //随机生成坐标点

         for (int i = 0; i < 10; i++) {
             int x1 = ran.nextInt(width);
             int x2 = ran.nextInt(width);

             int y1 = ran.nextInt(height);
             int y2 = ran.nextInt(height);
             g.drawLine(x1, y1, x2, y2);
         }

         //3.将图片输出到页面展示
         ImageIO.write(image, "jpg", response.getOutputStream());

     }

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         this.doPost(request, response);
     }
 }

CheckCodeServlet

2.登陆Servlet

 package com.isit.servlet;

 import com.isit.dao.UserDao;
 import com.isit.entity.User;
 import org.apache.commons.beanutils.BeanUtils;

 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
 import java.util.Map;

 /**
  * @program: LoginServlet
  * @description: 登陆
  * @author: wxh
  * @date: 2019-06-11 15:03
  **/
 @WebServlet("/loginServlet")
 public class LoginServlet extends HttpServlet {
     @Override
     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         this.doPost(req, resp);
     }

     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
         req.setCharacterEncoding("utf-8");
         //1.验证验证码是否正确
         HttpSession session = req.getSession();
         String checkCode = (String) session.getAttribute("checkCode");
         //1.1.验证码错误
         String code = req.getParameter("checkCode");
         if (checkCode != null && !checkCode.equalsIgnoreCase(code)) {
             req.setAttribute("msg", "验证码错误");
             req.getRequestDispatcher("/index.jsp").forward(req, resp);
         } else {
             //1.2.验证码正确
             //2.校验登陆密码
             User user = new User();
             Map<String, String[]> parameterMap = req.getParameterMap();
             //使用BeanUtils工具类封装成JavaBean对象
             try {
                 BeanUtils.populate(user, parameterMap);
             } catch (IllegalAccessException e) {
                 e.printStackTrace();
             } catch (InvocationTargetException e) {
                 e.printStackTrace();
             }
             UserDao userDao = new UserDao();
             User entity = userDao.checkUser(user);
             if (entity != null) {
                 //2.1.匹配重定向到登录成功 Success.jsp 页面
                 session.setAttribute("username", entity.getUsername());
                 resp.sendRedirect(req.getContextPath() + "/success.jsp");
             } else {
                 //2.2.不匹配，转发到登陆界面
                 req.setAttribute("msg", "用户名或密码错误");
                 req.getRequestDispatcher("/index.jsp").forward(req, resp);
             }
         }
     }
 }

LoginServlet

3.JavaBean实体类代码

 package com.isit.entity;

 /**
  * @program: User
  * @description: User实体类
  * @author: wxh
  * @date: 2019-06-11 14:15
  **/
 public class User {
     private String id;
     private String username;
     private String password;

     public String getId() {
         return id;
     }

     public void setId(String id) {
         this.id = id;
     }

     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;
     }
 }

User

4.UserDao数据库操作层

 package com.isit.dao;

 import com.isit.entity.User;
 import com.isit.utils.JDBCUtils;
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.jdbc.core.RowMapper;

 import java.sql.ResultSet;
 import java.sql.SQLException;

 /**
  * @program: UserDao
  * @description: UserDao
  * @author: wxh
  * @date: 2019-06-11 14:46
  **/
 public class UserDao {
     JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());

     public User checkUser(User user){
         String sql = "select * from user where username = ? and password = ?";
         try{
             User entity= jdbcTemplate.queryForObject(sql, new RowMapper<User>() {
                 @Override
                 public User mapRow(ResultSet resultSet, int i) throws SQLException {
                     User user = new User();
                     String username = resultSet.getString("username");
                     String password = resultSet.getString("password");
                     user.setUsername(username);
                     user.setPassword(password);
                     return user;
                 }
             },user.getUsername(),user.getPassword());
             return entity;
         }catch (Exception e){
             e.printStackTrace();
             return null;
         }
     }

 }

UserDao

5.JDBC工具类

 package com.isit.utils;

 import com.alibaba.druid.pool.DruidDataSourceFactory;

 import javax.sql.DataSource;
 import java.io.IOException;
 import java.io.InputStream;
 import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.Properties;

 /**
  * @program: JDBCUtils
  * @description: 数据库连接池工具类
  * @author: wxh
  * @date: 2019-06-11 14:17
  **/
 public class JDBCUtils {

     private static DataSource ds;
     static {
         Properties properties = new Properties();
         InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
         try {
             properties.load(resourceAsStream);
             ds = DruidDataSourceFactory.createDataSource(properties);
         } catch (IOException e) {
             e.printStackTrace();
         }catch (Exception e) {
             e.printStackTrace();
         }
     }

     public static DataSource getDataSource(){
         return ds;
     }

     public static Connection getConnection() throws SQLException {
         return ds.getConnection();
     }

     public static void close(Connection con, Statement statement, ResultSet resultSet){
         if(resultSet !=null){
             try {
                 resultSet.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
         if(statement!=null){
             try {
                 statement.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
         if(con!=null){
             try {
                 con.close();
             } catch (SQLException e) {
                 e.printStackTrace();
             }
         }
     }

     public static void close(Connection connection,Statement statement){
         close(connection,statement,null);
     }

 }

JDBCUtils

6.JSP页面

 <%--
   Created by IntelliJ IDEA.
   User: isit
   Date: 2019/6/11
   Time: 14:09
   To change this template use File | Settings | File Templates.
 --%>
 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 <html>
   <head>
     <title>登陆</title>
     <script>
       window.onload= function () {
         document.getElementById("img").onclick=function () {
           this.src = "/loginJsp/checkCodeServlet?time="+ new Date().getTime();
         }
       }
     </script>
   </head>

   <body>
   <form method="post" action="/loginJsp/loginServlet">
     <div>登录名：<input type="text" name="username"></div>
     <div>密  码：<input type="password" name="password"></div>
     <div><img src="/loginJsp/checkCodeServlet" id="img"></div>
     <div> <input type="text" name="checkCode"></div>
     <div><input type="submit"></div>
   </form>
   <div><%=request.getAttribute("msg")%></div>
   </body>
 </html>

index.jsp

 <%--
   Created by IntelliJ IDEA.
   User: isit
   Date: 2019/6/11
   Time: 16:11
   To change this template use File | Settings | File Templates.
 --%>
 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 <html>
 <head>
     <title>登陆成功</title>
 </head>
 <body>
 <h1>
     <%=request.getSession().getAttribute("username")%> ，登陆成功
 </h1>
 </body>
 </html>

success.jsp

总结：

1.实现登陆操作需要验证码Servlet和登陆Servlet两个Servlet，一个会话中需要请求两次，一个生成验证码图片，一个做验证操作（验证码匹配和登陆账号密码匹配）；

2.CheckCodeServlet生成验证码图片到index.jsp页面，并将生成的验证码存到session中，以供LoginServlet做验证码验证操作；

3.LoginServlet需要两步验证，（1）验证验证码（2）验证登陆名和密码

3.1.通过HttpServletRequst对象获取Session对象，从Session对象中获取CheckCodeServlet添加到session中的验证码，以做验证操作，成功，继续下一步的登陆名和密码操作，失败，转发到登陆index.jsp页面，提示验证码错误；

3.2.验证码校验通过后，通过Dao层操作数据库返回查询结果（使用Druid数据库连接池，并使用JDBCTemple对数据库连接池对象进行封装，执行queryForObject方法返回实体类User）

3.3.校验通过，设置登陆名到session中（setAttribute），重定向到success.jsp页面，jsp页面取session中存放的登录名，展示XXX，登陆成功；

3.4.校验失败，转发到index.jsp页面中，提示登陆名密码错误。