java连接mysql数据库驱动

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.33</version> <!-- 请使用最新版本，可到 https://mvnrepository.com/artifact/mysql/mysql-connector-java 查看 -->
</dependency>

import java.sql.*;

public class MySQLExample {
    public static void main(String[] args) {
        // JDBC URL, 用户名和密码
        String url = "jdbc:mysql://localhost:3306/你的数据库名?useSSL=false&serverTimezone=UTC";
        String user = "root";      // 替换为你的用户名
        String password = "123456"; // 替换为你的密码

        Connection connection = null;
        Statement statement = null;
        ResultSet resultSet = null;

        try {
            // 1. 加载驱动（MySQL 8.x 可省略，因为 JDBC4 可自动加载，但显式写上也无害）
            Class.forName("com.mysql.cj.jdbc.Driver");

            // 2. 建立连接
            connection = DriverManager.getConnection(url, user, password);
            System.out.println("数据库连接成功！");

            // 3. 创建 Statement 对象
            statement = connection.createStatement();

            // 4. 执行 SQL 查询
            String sql = "SELECT * FROM your_table"; // 替换为你的表名
            resultSet = statement.executeQuery(sql);

            // 5. 处理结果集
            while (resultSet.next()) {
                // 假设表中有 id 和 name 两个字段
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                System.out.println("ID: " + id + ", Name: " + name);
            }

        } catch (ClassNotFoundException e) {
            System.err.println("找不到 JDBC 驱动类！");
            e.printStackTrace();
        } catch (SQLException e) {
            System.err.println("数据库连接或查询出错！");
            e.printStackTrace();
        } finally {
            // 6. 关闭资源（倒序关闭）
            try {
                if (resultSet != null) resultSet.close();
                if (statement != null) statement.close();
                if (connection != null) connection.close();
                System.out.println("数据库连接已关闭。");
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

jdbc:mysql://<host>:<port>/<database>?<参数>

jdbc:mysql://localhost:3306/testdb?useSSL=false&serverTimezone=UTC&allowPublicKeyRetrieval=true

jdbc:mysql://localhost:3306/你的数据库名?useSSL=false&serverTimezone=Asia/Shanghai&characterEncoding=utf8mb4

The server time zone value 'xxx' is unrecognized ...

import java.sql.*;

public class MySQLExampleSimple {
    public static void main(String[] args) {
        String url = "jdbc:mysql://localhost:3306/testdb?useSSL=false&serverTimezone=UTC";
        String user = "root";
        String password = "123456";

        // 使用 try-with-resources 自动关闭资源
        try (Connection conn = DriverManager.getConnection(url, user, password);
             Statement stmt = conn.createStatement();
             ResultSet rs = stmt.executeQuery("SELECT * FROM your_table")) {

            System.out.println("连接成功，查询数据：");

            while (rs.next()) {
                System.out.println(rs.getInt("id") + ", " + rs.getString("name"));
            }

        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

serverTimezone=UTC
// 或者
serverTimezone=Asia/Shanghai

allowPublicKeyRetrieval=true