工厂模式

<?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();