maven中jdbc增删改查

在Maven项目中使用JDBC进行增删改查操作，你需要完成以下几个步骤：

1. 添加JDBC依赖：在项目的pom.xml文件中，添加jdbc相关的依赖。例如，如果你使用的是MySQL数据库，可以添加以下依赖：

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.26</version>
    </dependency>
</dependencies>

2. 创建数据库连接：在Java代码中，使用JDBC连接数据库。你需要提供数据库的URL、用户名和密码。示例代码如下：

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

public class DatabaseUtil {
    public static Connection getConnection() throws SQLException {
        String url = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "root";
        String password = "password";
        return DriverManager.getConnection(url, username, password);
    }
}

3. 执行SQL语句：使用获取的数据库连接对象，可以执行SQL语句进行增删改查操作。示例代码如下：

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

public class UserDao {
    public void insert(User user) throws SQLException {
        String sql = "INSERT INTO users (id, name, email) VALUES (?, ?, ?)";
        try (Connection conn = DatabaseUtil.getConnection();
             PreparedStatement statement = conn.prepareStatement(sql)) {
            statement.setInt(1, user.getId());
            statement.setString(2, user.getName());
            statement.setString(3, user.getEmail());
            statement.executeUpdate();
        }
    }

    public void update(User user) throws SQLException {
        String sql = "UPDATE users SET name = ?, email = ? WHERE id = ?";
        try (Connection conn = DatabaseUtil.getConnection();
             PreparedStatement statement = conn.prepareStatement(sql)) {
            statement.setString(1, user.getName());
            statement.setString(2, user.getEmail());
            statement.setInt(3, user.getId());
            statement.executeUpdate();
        }
    }

    public void delete(int userId) throws SQLException {
        String sql = "DELETE FROM users WHERE id = ?";
        try (Connection conn = DatabaseUtil.getConnection();
             PreparedStatement statement = conn.prepareStatement(sql)) {
            statement.setInt(1, userId);
            statement.executeUpdate();
        }
    }

    public User getById(int userId) throws SQLException {
        String sql = "SELECT * FROM users WHERE id = ?";
        try (Connection conn = DatabaseUtil.getConnection();
             PreparedStatement statement = conn.prepareStatement(sql)) {
            statement.setInt(1, userId);
            try (ResultSet resultSet = statement.executeQuery()) {
                if (resultSet.next()) {
                    User user = new User();
                    user.setId(resultSet.getInt("id"));
                    user.setName(resultSet.getString("name"));
                    user.setEmail(resultSet.getString("email"));
                    return user;
                }
            }
        }
        return null;
    }
}

以上是一个简单的示例，展示了在Maven项目中使用JDBC进行增删改查操作的基本步骤。你可以根据自己的需求进行修改和扩展。