java mysql用户账号管理系统开发

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DatabaseConnector {
    private static final String URL = "jdbc:mysql://localhost:3306/mydatabase";
    private static final String USER = "root";
    private static final String PASSWORD = "password";

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }

    public static void main(String[] args) {
        try (Connection connection = getConnection()) {
            System.out.println("数据库连接成功！");
        } catch (SQLException e) {
            System.out.println("数据库连接失败：" + e.getMessage());
        }
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class UserDAO {
    private Connection connection;

    public UserDAO(Connection connection) {
        this.connection = connection;
    }

    public boolean isValidUser(String username, String password) throws SQLException {
        String sql = "SELECT COUNT(*) FROM users WHERE username = ? AND password = ?";
        try (PreparedStatement statement = connection.prepareStatement(sql)) {
            statement.setString(1, username);
            statement.setString(2, password);
            return statement.executeQuery().next();
        }
    }
}

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class UserService {
    private UserDAO userDAO;

    public UserService(UserDAO userDAO) {
        this.userDAO = userDAO;
    }

    public synchronized boolean registerUser(String username, String password) throws SQLException {
        if (userDAO.isValidUser(username, password)) {
            return false;
        }
        String sql = "INSERT INTO users (username, password) VALUES (?, ?)";
        try (Connection connection = DatabaseConnector.getConnection();
             PreparedStatement statement = connection.prepareStatement(sql)) {
            statement.setString(1, username);
            statement.setString(2, password);
            return statement.executeUpdate() > 0;
        }
    }
}