function resize($srcname,$dst_w=150,$dst_h=120){
$dst=imagecreatetruecolor($dst_w,$dst_h);
// $src="imagecreatefrom".$ext($srcname);
$imageinfo=getimagesize($srcname);
$ex=explode("/",$imageinfo['mime']);
$ext=end($ex);//后缀名
$create="imagecreatefrom".$ext;//拼接函数
$src=$create($srcname);//imagecreatefromjpeg()
$src_w=$imageinfo['0'];
$src_h=$imageinfo['1'];
imagecopyresampled($dst,$src,0,0,0,0,$dst_w,$dst_h,$src_w,$src_h);
header('content-type:'.$imageinfo['mime']);
$showimg="image".$ext;//拼接函数
$showimg($dst);
imagedestroy($src);
imagedestroy($dst);
}