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java如何使用mysql

2026-03-03 23:37:18Java

使用Java连接MySQL数据库

Java通过JDBC（Java Database Connectivity）API与MySQL数据库进行交互。以下是详细步骤和示例代码。

添加MySQL JDBC驱动依赖

在项目中添加MySQL JDBC驱动的依赖。如果使用Maven，在pom.xml中添加以下依赖：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.28</version>
</dependency>

如果手动添加，下载MySQL Connector/J的JAR文件并添加到项目的类路径中。

建立数据库连接

使用DriverManager获取数据库连接。需要提供数据库URL、用户名和密码。

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

public class MySQLConnection {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/your_database";
        String username = "your_username";
        String password = "your_password";

        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            System.out.println("Connected to the database!");
            connection.close();
        } catch (SQLException e) {
            System.out.println("Connection failed!");
            e.printStackTrace();
        }
    }
}

执行SQL查询

使用Statement或PreparedStatement执行SQL查询。PreparedStatement更安全，能防止SQL注入。

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

public class QueryExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/your_database";
        String username = "your_username";
        String password = "your_password";

        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            String sql = "SELECT * FROM users WHERE id = ?";
            PreparedStatement statement = connection.prepareStatement(sql);
            statement.setInt(1, 1); // 设置参数
            ResultSet resultSet = statement.executeQuery();

            while (resultSet.next()) {
                System.out.println("User: " + resultSet.getString("name"));
            }

            resultSet.close();
            statement.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

插入、更新和删除数据

使用PreparedStatement执行插入、更新和删除操作。

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

public class InsertExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/your_database";
        String username = "your_username";
        String password = "your_password";

        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            String sql = "INSERT INTO users (name, email) VALUES (?, ?)";
            PreparedStatement statement = connection.prepareStatement(sql);
            statement.setString(1, "John Doe");
            statement.setString(2, "john.doe@example.com");
            int rowsInserted = statement.executeUpdate();
            System.out.println(rowsInserted + " row(s) inserted.");

            statement.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

处理事务

使用Connection对象管理事务，确保数据一致性。

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

public class TransactionExample {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/your_database";
        String username = "your_username";
        String password = "your_password";

        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            connection.setAutoCommit(false); // 关闭自动提交

            String sql1 = "UPDATE accounts SET balance = balance - 100 WHERE id = 1";
            String sql2 = "UPDATE accounts SET balance = balance + 100 WHERE id = 2";

            PreparedStatement statement1 = connection.prepareStatement(sql1);
            PreparedStatement statement2 = connection.prepareStatement(sql2);

            statement1.executeUpdate();
            statement2.executeUpdate();

            connection.commit(); // 提交事务
            System.out.println("Transaction completed.");

            statement1.close();
            statement2.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

使用连接池

为了提高性能，可以使用连接池管理数据库连接。常见的连接池库有HikariCP、Apache DBCP等。

以下是使用HikariCP的示例：

java如何使用mysql

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import java.sql.Connection;
import java.sql.SQLException;

public class ConnectionPoolExample {
    public static void main(String[] args) {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl("jdbc:mysql://localhost:3306/your_database");
        config.setUsername("your_username");
        config.setPassword("your_password");
        config.setMaximumPoolSize(10);

        HikariDataSource dataSource = new HikariDataSource(config);

        try {
            Connection connection = dataSource.getConnection();
            System.out.println("Connection obtained from pool.");
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            dataSource.close();
        }
    }
}