使用IDEA 编写一个增删改查

好的，以下是一个基于Java和MySQL数据库的增删改查示例：

1. 首先，在MySQL数据库中创建一个名为“test”的数据库，并在其中创建一个名为“users”的表，该表包含以下列：id（INT），name（VARCHAR（50）），age（INT）和email（VARCHAR（100））。

2. 在IDEA中创建一个Java项目，并添加MySQL驱动程序和JDBC库。

3. 创建一个名为“User”的Java类，该类具有以下属性：id，name，age和email，并创建相应的Setter和Getter方法。

4. 创建一个名为“UserDAO”的Java类，在该类中实现增删改查的方法。以下是示例代码：

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class UserDAO {
    private Connection connection;

    public UserDAO() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection("jdbc:mysql://localhost/test", "root", "");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public List<User> getAllUsers() {
        List<User> users = new ArrayList<User>();
        try {
            Statement statement = connection.createStatement();
            ResultSet rs = statement.executeQuery("SELECT * FROM users");
            while (rs.next()) {
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setAge(rs.getInt("age"));
                user.setEmail(rs.getString("email"));
                users.add(user);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return users;
    }

    public User getUserById(int id) {
        User user = new User();
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM users WHERE id=?");
            preparedStatement.setInt(1, id);
            ResultSet rs = preparedStatement.executeQuery();
            if (rs.next()) {
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setAge(rs.getInt("age"));
                user.setEmail(rs.getString("email"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return user;
    }

    public void addUser(User user) {
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("INSERT INTO users(name, age, email) VALUES (?, ?, ?)");
            preparedStatement.setString(1, user.getName());
            preparedStatement.setInt(2, user.getAge());
            preparedStatement.setString(3, user.getEmail());
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void updateUser(User user) {
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("UPDATE users SET name=?, age=?, email=? WHERE id=?");
            preparedStatement.setString(1, user.getName());
            preparedStatement.setInt(2, user.getAge());
            preparedStatement.setString(3, user.getEmail());
            preparedStatement.setInt(4, user.getId());
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void deleteUser(int id) {
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("DELETE FROM users WHERE id=?");
            preparedStatement.setInt(1, id);
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

5. 创建一个名为“Main”的Java类，该类包含主函数和用户交互。

import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        UserDAO userDAO = new UserDAO();
        Scanner scanner = new Scanner(System.in);
        boolean running = true;
        while (running) {
            System.out.println("请选择操作：");
            System.out.println("1. 查询所有用户");
            System.out.println("2. 根据id查询用户");
            System.out.println("3. 添加用户");
            System.out.println("4. 更新用户");
            System.out.println("5. 删除用户");
            System.out.println("0. 退出");
            String option = scanner.nextLine();
            switch (option) {
                case "1":
                    List<User> users = userDAO.getAllUsers();
                    for (User user : users) {
                        System.out.println(user.getId() + "\t" + user.getName() + "\t" + user.getAge() + "\t" + user.getEmail());
                    }
                    break;
                case "2":
                    System.out.println("请输入用户id：");
                    int id = scanner.nextInt();
                    scanner.nextLine();
                    User user = userDAO.getUserById(id);
                    System.out.println(user.getId() + "\t" + user.getName() + "\t" + user.getAge() + "\t" + user.getEmail());
                    break;
                case "3":
                    System.out.println("请输入用户姓名：");
                    String name = scanner.nextLine();
                    System.out.println("请输入用户年龄：");
                    int age = scanner.nextInt();
                    scanner.nextLine();
                    System.out.println("请输入用户邮箱：");
                    String email = scanner.nextLine();
                    User newUser = new User();
                    newUser.setName(name);
                    newUser.setAge(age);
                    newUser.setEmail(email);
                    userDAO.addUser(newUser);
                    System.out.println("用户添加成功！");
                    break;
                case "4":
                    System.out.println("请输入用户id：");
                    int updateId = scanner.nextInt();
                    scanner.nextLine();
                    User updateUser = userDAO.getUserById(updateId);
                    System.out.println("请输入新的姓名：");
                    String updateName = scanner.nextLine();
                    System.out.println("请输入新的年龄：");
                    int updateAge = scanner.nextInt();
                    scanner.nextLine();
                    System.out.println("请输入新的邮箱：");
                    String updateEmail = scanner.nextLine();
                    updateUser.setName(updateName);
                    updateUser.setAge(updateAge);
                    updateUser.setEmail(updateEmail);
                    userDAO.updateUser(updateUser);
                    System.out.println("用户更新成功！");
                    break;
                case "5":
                    System.out.println("请输入用户id：");
                    int deleteId = scanner.nextInt();
                    scanner.nextLine();
                    userDAO.deleteUser(deleteId);
                    System.out.println("用户删除成功！");
                    break;
                case "0":
                    running = false;
                    break;
                default:
                    System.out.println("输入有误，请重新输入！");
                    break;
            }
        }
    }
}

6. 运行Main类，即可进行增删改查操作。