登录页验证码小案例

覃浩

发布于：2021年7月21日

Java

字数：1.7k字

时长：9分钟

次浏览

案例需求：
1. 访问带有验证码的登录页面login.jsp
2. 用户输入用户名，密码以及验证码。

如果用户名和密码输入有误，跳转登录页面，提示:用户名或密码错误

如果验证码输入有误，跳转登录页面，提示：验证码错误

如果全部输入正确，则跳转到主页success.jsp，显示：用户名,欢迎您

目录结构

├─src
│ │ druid.properties
│ │
│ └─cn
│ └─imqinhao
│ ├─dao
│ │ UserDao.java
│ │
│ ├─domain
│ │ User.java
│ │
│ ├─servlet
│ │ CheckCodeServlet.java
│ │ LoginServlet.java
│ │
│ └─utils
│ JDBCUtil.java
│
└─web
│ login.jsp
│ success.jsp
│
└─WEB-INF
└─lib
commons-beanutils-1.8.0.jar
commons-logging-1.2.jar
druid-1.2.6.jar
mchange-commons-java-0.2.12.jar
mysql-connector-java-8.0.25.jar
servlet-api.jar
spring-beans-5.0.0.RELEASE.jar
spring-core-5.0.0.RELEASE.jar
spring-jdbc-5.0.0.RELEASE.jar
spring-tx-5.0.0.RELEASE.jar

创建数据库

先创建数据库

1	CREATE DATABASE day16;

使用day16数据库

1	USE day16;

创建user表

CREATE TABLE USER(
	id INT PRIMARY KEY AUTO_INCREMENT,
	username VARCHAR(32) UNIQUE NOT NULL,
	PASSWORD VARCHAR(16) NOT NULL
);

写入一些数据

1 2	INSERT INTO USER VALUES(NULL, "qinhao", "qinhao123"); INSERT INTO USER VALUES(NULL, "lareina", "lareina123");

<%--
  User: qinhao
  Date: 2021/7/21
  Time: 12:52
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>login</title>
    <script>
        window.onload = function () {
            document.getElementById("checkCode").onclick = function () {
                this.src = "/day16/checkCodeServlet?time=" + new Date().getTime();
            }
        }
    </script>
    <style>
        div {
            color: red;
        }
    </style>
</head>
<body>
    <form action="/day16/loginServlet" method="post">
        <table>
            <tr>
                <td>用户名</td>
                <td>
                    <input type="text" name="username">
                </td>
            </tr>
            <tr>
                <td>密码</td>
                <td>
                    <input type="password" name="password">
                </td>
            </tr>
            <tr>
                <td>验证码</td>
                <td>
                    <input type="text" name="checkCode">
                </td>
            </tr>
            <tr>
                <td colspan="2">
                    <img id="checkCode" src="/day16/checkCodeServlet">
                </td>
            </tr>
            <tr>
                <td colspan="2">
                    <input type="submit" value="登录">
                </td>
            </tr>
        </table>
    </form>

    <div>
        <%= request.getSession().getAttribute("checkCode_error") == null ? "" : request.getSession().getAttribute("checkCode_error") %>
        <%= request.getSession().getAttribute("common_error") == null ? "" : request.getSession().getAttribute("common_error") %>
    </div>
</body>
</html>

User类

package cn.imqinhao.domain;

public class User {
    private int id;
    private String username;
    private String password;

    public int getId() {
        return id;
    }

    public void setId(int 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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

JDBCUtils类

package cn.imqinhao.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.SQLException;
import java.util.Properties;

public class JDBCUtil {
    private static DataSource dataSource;

    static {
        try {
            // 加载配置文件
            Properties properties = new Properties();
            InputStream resourceAsStream = JDBCUtil.class.getClassLoader().getResourceAsStream("druid.properties");
            properties.load(resourceAsStream);
            // 初始化连接对象
            dataSource = DruidDataSourceFactory.createDataSource(properties);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static DataSource getDataSource() {
        return dataSource;
    }

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

UserDao类

package cn.imqinhao.dao;

import cn.imqinhao.domain.User;
import cn.imqinhao.utils.JDBCUtil;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

public class UserDao {
    private JdbcTemplate template = new JdbcTemplate(JDBCUtil.getDataSource());

    public User login(User loginUser) {
        try {
            // 编写sql
            String sql = "select * from user where username = ? and password = ?";
            // 执行sql
            User user = template.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class), loginUser.getUsername(), loginUser.getPassword());
            // 返回user对象
            return user;
        } catch (DataAccessException e) {
            e.printStackTrace();
            return null;
        }

    }
}

CheckCodeServlet类

package cn.imqinhao.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 {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        int width = 100;
        int height = 50;
        // 1.创建对象，在内存存放图片（验证码图片对象）
        BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 2.美化图片
        Graphics graphics = bufferedImage.getGraphics();
        // 填充背景色
        graphics.setColor(Color.pink);  // 设置画笔颜色
        graphics.fillRect(0, 0, width, height); // 填充背景颜色
        // 画边框
        graphics.setColor(Color.BLUE);  // 设置画笔颜色
        graphics.drawRect(0, 0, width - 1, height - 1); // 绘制边框

        String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        StringBuilder sb = new StringBuilder();
        // 生成随机角标
        Random random = new Random();
        for (int i = 1; i <= 4; i++) {
            int index = random.nextInt(str.length());   // 生成随机数索引
            // 获取字符
            char ch = str.charAt(index);    // 抽取随机字符
            sb.append(ch);
            // 写入验证码
            graphics.drawString(ch+"", width / 5 * i, height / 2);
        }
        String checkCode_str = sb.toString();
        // 添加到session中
        HttpSession session = req.getSession();
        session.setAttribute("checkCode_str", checkCode_str);
        // 生成干扰线
        graphics.setColor(Color.GREEN);
        for (int i = 1; i <= 10; i++) {
            int x1 = random.nextInt(width);
            int x2 = random.nextInt(width);
            int y1 = random.nextInt(height);
            int y2 = random.nextInt(height);
            graphics.drawLine(x1, y1, x2, y2);
        }

        // 3.将图片输出到页面上
        ImageIO.write(bufferedImage, "jpg", resp.getOutputStream());
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
}

LoginServlet类

package cn.imqinhao.servlet;

import cn.imqinhao.dao.UserDao;
import cn.imqinhao.domain.User;

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;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 获取生成的验证码
        HttpSession session = req.getSession();
        String checkCode = (String) session.getAttribute("checkCode_str");
        // 获取用户输入的验证码
        String user_checkCode = req.getParameter("checkCode");
        // 清除系统生成的验证码
        session.removeAttribute("checkCode_str");
        if(checkCode != null && checkCode.equalsIgnoreCase(user_checkCode)) {
            // 获取输入的数据
            String username = req.getParameter("username");
            String password = req.getParameter("password");
            // 创建user对象
            User user = new User();
            user.setUsername(username);
            user.setPassword(password);
            // 创建userDao对象
            UserDao userDao = new UserDao();
            User loginUser = userDao.login(user);
            // 查到了
            if(loginUser != null) {
                // 登录成功
                // 持久化存储
                session.setAttribute("user", user.getUsername());
                // 转发
                resp.sendRedirect(req.getContextPath() + "/success.jsp");
            } else {
                // 用户名或密码错误
                session.setAttribute("common_error", "账号或密码错误");
                // 转发
                req.getRequestDispatcher("/login.jsp").forward(req, resp);
            }
        } else {
            // 验证码错误
            session.setAttribute("checkCode_error", "验证码错误");
            // 转发
            req.getRequestDispatcher("/login.jsp").forward(req, resp);
        }
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
}

success.jsp

<%--
  Created by IntelliJ IDEA.
  User: qinhao
  Date: 2021/7/21
  Time: 13:35
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>登录成功</title>
</head>
<body>
    <h1><%= request.getSession().getAttribute("user") %>，欢迎您</h1>
</body>
</html>

druid.properties配置文件

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/day16
username=root
password=XXXXXXXX
initialSize=5
maxActive=10
maxWait=3000

更新于：2021年7月21日

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