Java JDBC 連接 金倉、達夢、MySQL、Oracle數據庫 示例

package utils;

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

public class DBUtil
{
    //kingbase7
//    private static final String DB_URL = "jdbc:kingbase://13.90.3.40:54321/PSM2000";
//    private static final String USERNAME = "PSM";
//    private static final String PASSWORD = "METERAGE"; 

    //kingbase8
//    private static final String DB_URL = "jdbc:kingbase8://localhost:54321/FR3000W";
//    private static final String USERNAME = "PSM";
//    private static final String PASSWORD = "meterage"; 

    //oracle
//    private static final String DB_URL = "jdbc:oracle:thin:@192.168.1.111:1521:orcl12";
//    private static final String USERNAME = "psm";
//    private static final String PASSWORD = "meterage"; 

    //dm7
//    private static final String DB_URL = "jdbc:dm://localhost:5236/psm";
//    private static final String USERNAME = "SYSDBA";
//    private static final String PASSWORD = "SYSDBA"; 

    //mysql(Version>=8.0)
    private static final String DB_URL = "jdbc:mysql://localhost:3306/psm2000?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "root"; 

    private static Connection conn = null;

    public static Connection getConnection()
    {
        try
        {
            if( conn == null )
            {
//                DriverManager.registerDriver( new com.kingbase.Driver() );
//                DriverManager.registerDriver( new com.kingbase8.Driver() );
//                DriverManager.registerDriver( new oracle.jdbc.OracleDriver() );
//                DriverManager.registerDriver( new dm.jdbc.driver.DmDriver() );
                DriverManager.registerDriver( new com.mysql.cj.jdbc.Driver() );
                conn = DriverManager.getConnection( DB_URL, USERNAME, PASSWORD );
                return conn;
            }
        }
        catch( Exception e )
        {
            e.printStackTrace();
        }

        return conn;
    }

    ///////////////////////////////////////////////////////////////////////////

    //test begin
    public static void queryErtu() throws Exception
    {
        String strSql = "select * from ertu";
        conn = getConnection();
        try
        {
            PreparedStatement pst = conn.prepareStatement( strSql );
            ResultSet ret = pst.executeQuery();
            while( ret.next() )
            {
                System.out.println( ret.getString("ertu_no") + "--" + ret.getString("ertu_name") + "--" + ret.getString("run_ratio") );
            }
            ret.close();
            pst.close();
        }
        catch( SQLException e )
        {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws Exception
    {
        System.out.println( "Query Ertu:" );
        queryErtu();
    }
    //test end
}