java连接mysql实现登录注册

环境准备

1、安装MySQL数据库，并创建用户表和用户信息表。

CREATE DATABASE test;
USE test;
CREATE TABLE user (
  id INT PRIMARY KEY AUTO_INCREMENT,
  username VARCHAR(255) NOT NULL UNIQUE,
  password VARCHAR(255) NOT NULL
);

2、下载MySQL Connector/J（JDBC驱动），并将其添加到Java项目的类路径中。

Java代码实现登录注册功能

1、导入相关包：

import java.sql.*;
import java.util.Scanner;

2、编写数据库连接工具类：

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
    private static final String USER = "root";
    private static final String PASSWORD = "your_password";
    static {
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    public static Connection getConnection() {
        return null;
    }
}

3、编写用户类：

public class User {
    private int id;
    private String username;
    private String password;
    // 构造方法、getter和setter方法省略...
}

4、编写用户管理类：

public class UserManager {
    public boolean register(User user) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        try {
            connection = DBUtil.getConnection();
            String sql = "INSERT INTO user (username, password) VALUES (?, ?)";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, user.getUsername());
            preparedStatement.setString(2, user.getPassword());
            int result = preparedStatement.executeUpdate();
            return result > 0;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源...
        }
        return false;
    }
    public User login(String username, String password) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        try {
            connection = DBUtil.getConnection();
            String sql = "SELECT * FROM user WHERE username = ? AND password = ?";
            preparedStatement = connection.prepareStatement(sql);
            preparedStatement.setString(1, username);
            preparedStatement.setString(2, password);
            resultSet = preparedStatement.executeQuery();
            if (resultSet.next()) {
                User user = new User();
                user.setId(resultSet.getInt("id"));
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            } else {
                return null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭资源...
        }
        return null;
    }
}

5、编写主程序：

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请选择操作：1.注册 2.登录");
        int operation = scanner.nextInt();
        scanner.nextLine(); // 清除缓冲区换行符
        UserManager userManager = new UserManager();
        switch (operation) {
            case 1: // 注册操作
                System.out.println("请输入用户名：");
                String username = scanner.nextLine();
                System.out.println("请输入密码：");
                String password = scanner.nextLine();
                if (userManager.register(new User(username, password))) {
                    System.out.println("注册成功！");
                } else {
                    System.out.println("注册失败，请检查用户名是否已存在！");
                }
                break;
            case 2: // 登录操作
                System.out.println("请输入用户名：");
                String inputUsername = scanner.nextLine();
                System.out.println("请输入密码：");
                String inputPassword = scanner.nextLine();
                User user = userManager.login(inputUsername, inputPassword);
                if (user != null) {
                    System.out.println("登录成功，欢迎 " + user.getUsername() + "！");
                } else {
                    System.out.println("登录失败，请检查用户名和密码是否正确！");
                }
                break;
            default: // 无效操作，退出程序
                System.out.println("无效操作，程序退出！");
                break;
        }
    }
}