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();   
  }   
  }   
  }