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Session实现验证码登陆笔记

分类: IT文章 • 2025-02-07 19:51:43

1.生成验证码Servlet

 1 package com.isit.servlet;
 2 
 3 import javax.imageio.ImageIO;
 4 import javax.servlet.ServletException;
 5 import javax.servlet.annotation.WebServlet;
 6 import javax.servlet.http.HttpServlet;
 7 import javax.servlet.http.HttpServletRequest;
 8 import javax.servlet.http.HttpServletResponse;
 9 import javax.servlet.http.HttpSession;
10 import java.awt.*;
11 import java.awt.image.BufferedImage;
12 import java.io.IOException;
13 import java.util.Random;
14 
15 @WebServlet("/checkCodeServlet")
16 public class CheckCodeServlet extends HttpServlet {
17     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
18 
19 
20         int width = 100;
21         int height = 50;
22 
23         //1.创建一对象，在内存中图片(验证码图片对象)
24         BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
25 
26 
27         //2.美化图片
28         //2.1 填充背景色
29         Graphics g = image.getGraphics();//画笔对象
30         g.setColor(Color.PINK);//设置画笔颜色
31         g.fillRect(0, 0, width, height);
32 
33         //2.2画边框
34         g.setColor(Color.BLUE);
35         g.drawRect(0, 0, width - 1, height - 1);
36 
37         String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
38         //生成随机角标
39         StringBuffer sb = new StringBuffer();
40         Random ran = new Random();
41         for (int i = 1; i <= 4; i++) {
42             int index = ran.nextInt(str.length());
43             //获取字符
44             char ch = str.charAt(index);//随机字符
45             sb.append(ch);
46             //2.3写验证码
47             g.drawString(ch + "", width / 5 * i, height / 2);
48         }
49         String checkCode = sb.toString();
50         HttpSession session = request.getSession();
51         session.setAttribute("checkCode", checkCode);
52         //2.4画干扰线
53         g.setColor(Color.GREEN);
54 
55         //随机生成坐标点
56 
57         for (int i = 0; i < 10; i++) {
58             int x1 = ran.nextInt(width);
59             int x2 = ran.nextInt(width);
60 
61             int y1 = ran.nextInt(height);
62             int y2 = ran.nextInt(height);
63             g.drawLine(x1, y1, x2, y2);
64         }
65 
66 
67         //3.将图片输出到页面展示
68         ImageIO.write(image, "jpg", response.getOutputStream());
69 
70 
71     }
72 
73     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
74         this.doPost(request, response);
75     }
76 }
CheckCodeServlet

2.登陆Servlet

 1 package com.isit.servlet;
 2 
 3 import com.isit.dao.UserDao;
 4 import com.isit.entity.User;
 5 import org.apache.commons.beanutils.BeanUtils;
 6 
 7 import javax.servlet.ServletException;
 8 import javax.servlet.annotation.WebServlet;
 9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 import javax.servlet.http.HttpSession;
13 import java.io.IOException;
14 import java.lang.reflect.InvocationTargetException;
15 import java.util.Map;
16 
17 /**
18  * @program: LoginServlet
19  * @description: 登陆
20  * @author: wxh
21  * @date: 2019-06-11 15:03
22  **/
23 @WebServlet("/loginServlet")
24 public class LoginServlet extends HttpServlet {
25     @Override
26     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
27         this.doPost(req, resp);
28     }
29 
30     @Override
31     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
32         req.setCharacterEncoding("utf-8");
33         //1.验证验证码是否正确
34         HttpSession session = req.getSession();
35         String checkCode = (String) session.getAttribute("checkCode");
36         //1.1.验证码错误
37         String code = req.getParameter("checkCode");
38         if (checkCode != null && !checkCode.equalsIgnoreCase(code)) {
39             req.setAttribute("msg", "验证码错误");
40             req.getRequestDispatcher("/index.jsp").forward(req, resp);
41         } else {
42             //1.2.验证码正确
43             //2.校验登陆密码
44             User user = new User();
45             Map<String, String[]> parameterMap = req.getParameterMap();
46             //使用BeanUtils工具类封装成JavaBean对象
47             try {
48                 BeanUtils.populate(user, parameterMap);
49             } catch (IllegalAccessException e) {
50                 e.printStackTrace();
51             } catch (InvocationTargetException e) {
52                 e.printStackTrace();
53             }
54             UserDao userDao = new UserDao();
55             User entity = userDao.checkUser(user);
56             if (entity != null) {
57                 //2.1.匹配重定向到登录成功 Success.jsp 页面
58                 session.setAttribute("username", entity.getUsername());
59                 resp.sendRedirect(req.getContextPath() + "/success.jsp");
60             } else {
61                 //2.2.不匹配，转发到登陆界面
62                 req.setAttribute("msg", "用户名或密码错误");
63                 req.getRequestDispatcher("/index.jsp").forward(req, resp);
64             }
65         }
66     }
67 }
LoginServlet

3.JavaBean实体类代码

 1 package com.isit.entity;
 2 
 3 /**
 4  * @program: User
 5  * @description: User实体类
 6  * @author: wxh
 7  * @date: 2019-06-11 14:15
 8  **/
 9 public class User {
10     private String id;
11     private String username;
12     private String password;
13 
14     public String getId() {
15         return id;
16     }
17 
18     public void setId(String id) {
19         this.id = id;
20     }
21 
22     public String getUsername() {
23         return username;
24     }
25 
26     public void setUsername(String username) {
27         this.username = username;
28     }
29 
30     public String getPassword() {
31         return password;
32     }
33 
34     public void setPassword(String password) {
35         this.password = password;
36     }
37 }
User

4.UserDao数据库操作层

 1 package com.isit.dao;
 2 
 3 import com.isit.entity.User;
 4 import com.isit.utils.JDBCUtils;
 5 import org.springframework.jdbc.core.JdbcTemplate;
 6 import org.springframework.jdbc.core.RowMapper;
 7 
 8 import java.sql.ResultSet;
 9 import java.sql.SQLException;
10 
11 /**
12  * @program: UserDao
13  * @description: UserDao
14  * @author: wxh
15  * @date: 2019-06-11 14:46
16  **/
17 public class UserDao {
18     JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
19 
20     public User checkUser(User user){
21         String sql = "select * from user where username = ? and password = ?";
22         try{
23             User entity= jdbcTemplate.queryForObject(sql, new RowMapper<User>() {
24                 @Override
25                 public User mapRow(ResultSet resultSet, int i) throws SQLException {
26                     User user = new User();
27                     String username = resultSet.getString("username");
28                     String password = resultSet.getString("password");
29                     user.setUsername(username);
30                     user.setPassword(password);
31                     return user;
32                 }
33             },user.getUsername(),user.getPassword());
34             return entity;
35         }catch (Exception e){
36             e.printStackTrace();
37             return null;
38         }
39     }
40 
41 }
UserDao

5.JDBC工具类

 1 package com.isit.utils;
 2 
 3 import com.alibaba.druid.pool.DruidDataSourceFactory;
 4 
 5 import javax.sql.DataSource;
 6 import java.io.IOException;
 7 import java.io.InputStream;
 8 import java.sql.Connection;
 9 import java.sql.ResultSet;
10 import java.sql.SQLException;
11 import java.sql.Statement;
12 import java.util.Properties;
13 
14 /**
15  * @program: JDBCUtils
16  * @description: 数据库连接池工具类
17  * @author: wxh
18  * @date: 2019-06-11 14:17
19  **/
20 public class JDBCUtils {
21 
22     private static DataSource ds;
23     static {
24         Properties properties = new Properties();
25         InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
26         try {
27             properties.load(resourceAsStream);
28             ds = DruidDataSourceFactory.createDataSource(properties);
29         } catch (IOException e) {
30             e.printStackTrace();
31         }catch (Exception e) {
32             e.printStackTrace();
33         }
34     }
35 
36     public static DataSource getDataSource(){
37         return ds;
38     }
39 
40     public static Connection getConnection() throws SQLException {
41         return ds.getConnection();
42     }
43 
44     public static void close(Connection con, Statement statement, ResultSet resultSet){
45         if(resultSet !=null){
46             try {
47                 resultSet.close();
48             } catch (SQLException e) {
49                 e.printStackTrace();
50             }
51         }
52         if(statement!=null){
53             try {
54                 statement.close();
55             } catch (SQLException e) {
56                 e.printStackTrace();
57             }
58         }
59         if(con!=null){
60             try {
61                 con.close();
62             } catch (SQLException e) {
63                 e.printStackTrace();
64             }
65         }
66     }
67 
68     public static void close(Connection connection,Statement statement){
69         close(connection,statement,null);
70     }
71 
72 }
JDBCUtils

6.JSP页面

 1 <%--
 2   Created by IntelliJ IDEA.
 3   User: isit
 4   Date: 2019/6/11
 5   Time: 14:09
 6   To change this template use File | Settings | File Templates.
 7 --%>
 8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 9 <html>
10   <head>
11     <title>登陆</title>
12     <script>
13       window.onload= function () {
14         document.getElementById("img").onclick=function () {
15           this.src = "/loginJsp/checkCodeServlet?time="+ new Date().getTime();
16         }
17       }
18     </script>
19   </head>
20 
21   <body>
22   <form method="post" action="/loginJsp/loginServlet">
23     <div>登录名：<input type="text" name="username"></div>
24     <div>密  码：<input type="password" name="password"></div>
25     <div><img src="/loginJsp/checkCodeServlet" id="img"></div>
26     <div> <input type="text" name="checkCode"></div>
27     <div><input type="submit"></div>
28   </form>
29   <div><%=request.getAttribute("msg")%></div>
30   </body>
31 </html>
index.jsp 
 1 <%--
 2   Created by IntelliJ IDEA.
 3   User: isit
 4   Date: 2019/6/11
 5   Time: 16:11
 6   To change this template use File | Settings | File Templates.
 7 --%>
 8 <%@ page contentType="text/html;charset=UTF-8" language="java" %>
 9 <html>
10 <head>
11     <title>登陆成功</title>
12 </head>
13 <body>
14 <h1>
15     <%=request.getSession().getAttribute("username")%> ，登陆成功
16 </h1>
17 </body>
18 </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。

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