登录页验证码小案例

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 + '\'' +
                '}';
    }
}

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();
    }
}

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;
        }

    }
}

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);
    }
}

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);
    }
}