JDBC连接DB2、Oracle、MySQL、PostgreSQL

package com.terac.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class DBTest
{

  public static void main(String[] args)
 {
  try
  {
   String user = "user";
   String password = "password";
   String driver = "COM.ibm.db2.jdbc.net.DB2Driver";
   // "oracle.jdbc.driver.OracleDriver";
   // "com.mysql.jdbc.Driver";
   // "org.postgresql.Driver";
   String url = "jdbc:db2://localhost/a";
   // "jdbc:oracle:thin:@localhost:1521:a";
   // "jdbc:mysql://localhost/a";
   // "jdbc:postgresql://localhost:5740/a";
   String sql = "SELECT   current   timestamp   FROM   sysibm.sysdummy1";
   // "SELECT   sysdate   FROM   dual";
   // "SELECT   now()";
   // "SELECT   current_timestamp";
   Class.forName(driver).newInstance();
   Connection c = DriverManager.getConnection(url, user, password);
   Statement stmt = c.createStatement();
   ResultSet rs = stmt.executeQuery(sql);
   while (rs.next())
   {
    System.out.println(rs.getString(1));
   }
  } catch (Exception e)
  {
   e.printStackTrace();
  }
 }
}