Java URLClassLoader类来动态加载数据库驱动jar

使用Idea等开发工具可以很方便的自动加载驱动，但在生产环境就没有这么便捷的条件了。为了便于问题排查，于是就有了这种类似demo的小工具

import java.io.File;
import java.net.URL;
import java.net.URLClassLoader;
import java.sql.*;
import java.util.Properties;

public class DynamicMySQLConnectionWithoutConfigFile {
    public static void main(String[] args) {
        String jdbcJarPath = "/Users/xxxx/Downloads/mysql-connector-j-8.0.32.jar"; // 替换为 MySQL 驱动 .jar 路径

        // 直接提供数据库连接信息
        String dbUrl = "jdbc:mysql://192.168.1.19:3306/db"; // 数据库地址

        try {
            // 动态加载 MySQL 驱动 .jar
            File f = new File(jdbcJarPath);

            try (URLClassLoader classLoader = new URLClassLoader(new URL[]{f.toURI().toURL()}, System.class.getClassLoader())) {

                // 动态加载驱动类
                Class<?> driverClass = classLoader.loadClass("com.mysql.cj.jdbc.Driver");

                Driver sqlDriverInstance = ( Driver ) driverClass.newInstance();

                // 连接数据库
                System.out.println("正在连接数据库...");

                Properties userDbCredentials = new Properties();
                userDbCredentials.put( "user", "root" );
                userDbCredentials.put( "password", "xxxxx" );
                try (Connection connection = sqlDriverInstance.connect( dbUrl, userDbCredentials )) {
                    System.out.println("数据库连接成功!");

                    // 测试查询
                    String query = "SELECT VERSION() AS version";
                    try (Statement statement = connection.createStatement();
                         ResultSet resultSet = statement.executeQuery(query)) {
                        if (resultSet.next()) {
                            System.out.println("MySQL 版本: " + resultSet.getString("version"));
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}