<?php/** * 工厂模式 * Class DB */class DB{}class Mysql extends DB{    public function toString(){        echo ‘Mysql‘;    }}class Oracle extends DB{    public function toString(){        echo ‘Oracle‘;    }}class Mssql extends DB{    public function toString(){        echo ‘Mssql‘;    }}class DBFactory{    public static function db($dbType)    {        return new $dbType();    }}$handle=DBFactory::db(‘Oracle‘);echo $handle->toString();