碎碎念

function dl_file($file){

   //檢查檔案是否存在
   if (!is_file($file)) { die("404 File not found!"); }

   //取得檔案相關資料
   $len = filesize($file);
   $filename = basename($file);
   $file_extension = strtolower(substr(strrchr($filename,"."),1));

   //將檔案格式設定為將要下載的檔案
  switch( $file_extension ) {
     case "pdf": $ctype="application/pdf"; break;
     case "exe": $ctype="application/octet-stream"; break;
     case "zip": $ctype="application/zip"; break;
     case "doc": $ctype="application/msword"; break;
     case "xls": $ctype="application/vnd.ms-excel"; break;
     case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
     case "gif": $ctype="image/gif"; break;
     case "png": $ctype="image/png"; break;
     case "jpeg":
     case "jpg": $ctype="image/jpg"; break;
     case "mp3": $ctype="audio/mpeg"; break;
     case "wav": $ctype="audio/x-wav"; break;
     case "mpeg":
     case "mpg":
     case "mpe": $ctype="video/mpeg"; break;
     case "mov": $ctype="video/quicktime"; break;
     case "avi": $ctype="video/x-msvideo"; break;
     //禁止下面幾種類型的檔案被下載
     case "php":
     case "htm":
     case "html":
     case "txt": die("Cannot be used for ". $file_extension ." files!"); break;

     default: $ctype="application/force-download";
   }

   //開始編寫header
   header("Pragma: public");
   header("Expires: 0");
   header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
   header("Cache-Control: public");
   header("Content-Description: File Transfer");
   
   //使用利用 switch判別的檔案類型
   header("Content-Type: $ctype");

   //執行下載動作
   $header="Content-Disposition: attachment; filename=".$filename.";";
   header($header );
   header("Content-Transfer-Encoding: binary");
   header("Content-Length: ".$len);
   @readfile($file);
   exit;
}