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。

巴特西

Session实现验证码登陆笔记

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