$file_dir=$totalDirectory;
     $file_name=$filename;
     //echo ''./db/''.$file_dir.$file_name;
    if (file_exists($file_dir.$file_name)){
          $file=fopen($file_dir.$file_name,''r'');
         Header(''Content-type:application/octet-stream'');
         Header(''Accept-Ranges:bytes'');
         Header(''Content-Disposition:attachment;filename=''.$file_name);
         echo fread($file,filesize($file_dir.$file_name));
         fclose($file);
         exit;
        
     }else{
         echo ''file is not exists'';
     }

本文地址：http://www.phprm.com/code/728274f57cb981d9bc65bb1d40e3f7a4.html

转载随意，但请附上文章地址:-)