PHP判断上传文件类型的解决办法

/** * 读取文件前几个字节 判断文件类型 * @return String */ function checkTitle($filename){   $file=fopen($filename, "rb");   $bin=fread($file, 2); //只读2字节   fclose($file);   $strInfo =@unpack("c2chars", $bin);   $typeCode=intval($strInfo['chars1'].$strInfo['chars2']);   $fileType='';   switch($typeCode){     case 7790:       $fileType='exe';     break;     case 7784:       $fileType='midi';     break;     case 8297:       $fileType='rar';     break;     case 255216:       $fileType='jpg';     break;     case 7173:       $fileType='gif';     break;     case 6677:       $fileType='bmp';     break;     case 13780:       $fileType='png';     break;     default:       $fileType='unknown'.$typeCode;     break;   }   //Fix   if($strInfo['chars1']=='-1' && $strInfo['chars2']=='-40'){     return 'jpg';   }   if($strInfo['chars1']=='-119' && $strInfo['chars2']=='80'){     return 'png';   }   return $fileType; }