/**
* 将对象的数据重新初始化,用于多次重用一个SaeImgae对象
*
* <code>
* $img = new SaeImage( $bin );
* $img->resize(100);
* $data1 = $img->exec();
* $img->clean();
* $img->setData( $bin2 );
* $img->resize(300);
* $data2 = $img->exec();
* </code>
*
* @return void
* @author Lijun
*/
public function clean()
{
self::$_post = array();
self::$_img_data = NULL;
}