2024/10/6

软件设计实验一：

[实验任务二]：单一职责原则
登录模块在实际项目开发中很常见，请按照教材28页（PPT49页）利用单一职责原则重构后的类图实现这一模块。
实验要求：
1.    提交源代码和对应的数据库文件（注意将此模块保存，以备以后使用）；
MainClass:
public class MainClass {

    public static void main(String[] args) {
        new LoginForm();
    }
}
LoginForm:
public class LoginForm {
    private JTextField usernameField;
    private JPasswordField passwordField;
    private JButton loginButton;

    public LoginForm() {
        JFrame frame = new JFrame("登录");
        frame.setSize(300, 200);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(null);

        JLabel usernameLabel = new JLabel("用户名:");
        usernameLabel.setBounds(10, 20, 80, 25);
        frame.add(usernameLabel);

        usernameField = new JTextField(20);
        usernameField.setBounds(100, 20, 165, 25);
        frame.add(usernameField);

        JLabel passwordLabel = new JLabel("密码:");
        passwordLabel.setBounds(10, 50, 80, 25);
        frame.add(passwordLabel);

        passwordField = new JPasswordField(20);
        passwordField.setBounds(100, 50, 165, 25);
        frame.add(passwordField);

        loginButton = new JButton("登录");
        loginButton.setBounds(10, 80, 255, 25);
        frame.add(loginButton);

        loginButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                handleLogin();
            }
        });

        frame.setVisible(true);
    }

    private void handleLogin() {
        String username = usernameField.getText();
        String password = new String(passwordField.getPassword());

        if (UserDAO.login(username, password)) {
            JOptionPane.showMessageDialog(null, "登录成功");
        } else {
            JOptionPane.showMessageDialog(null, "用户名或密码错误");
        }
    }

    public static void main(String[] args) {
        new LoginForm();
    }
}

UserDAO:
public class UserDAO {
    public static boolean login(String username, String password) {
        Connection conn = DBUtil.getConnection();
        try {
            String sql = "SELECT * FROM users WHERE username = ? AND password = ?";
            PreparedStatement pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, username);
            pstmt.setString(2, password);
            ResultSet rs = pstmt.executeQuery();
            return rs.next(); // 如果能找到用户则登陆成功
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        } finally {
            DBUtil.closeConnection(conn);
        }
    }
}
DBUtil:
public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/design";
    private static final String USER = "root";
    private static final String PASSWORD = "1234";

    public static Connection getConnection() {
        try {
            return DriverManager.getConnection(URL, USER, PASSWORD);
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    public static void closeConnection(Connection conn) {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}
数据库设计部分：
create database design;
CREATE TABLE users (
                       id INT AUTO_INCREMENT PRIMARY KEY,  -- 用户唯一标识
                       username VARCHAR(50) NOT NULL UNIQUE,  -- 用户名，唯一
                       password VARCHAR(255) NOT NULL  -- 密码
);
insert into users(username,password) values('20223717','20223717');