Mysql::__construct PHP Method

    private function __construct()
    {
        $this->conn = mysql_connect('localhost', 'root', '');
    }

	public function __construct($port){   //重写了继承过父类的参数

		//有了保险，选继承父类的构造函数
		parent::__construct();
		$this->prot = $port;
		$this->conn = mysql_connect("localhost:$prot", 'root', '123456');
		echo $this->port,'----<br/>';



	}