問題描述

我用 PHP 創(chuàng)建了一個(gè)文件下載腳本，它可以工作，但網(wǎng)絡(luò)瀏覽器將文件報(bào)告為未知長(zhǎng)度".我的代碼如下:

I created a file download script in PHP, it works, but web browsers report the file as "Unknown Length". My code is as follows:

function downloadFile($file){
  // Set up the download system...
  header('Content-Description: File Transfer');
  header('Content-Type: '.mime_content_type($file));
  header('Content-Disposition: attachment; filename="'.basename($file).'"');
  header('Content-Transfer-Encoding: binary');
  header('Expires: 0');
  header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
  header('Pragma: public');
  header('Content-Length: '.filesize($file));

  // Flush the cache
  ob_clean();
  flush();

  // Send file to browser
  readfile($file);

  // DO NOT DO ANYTHING AFTER FILE DOWNLOAD
  exit;
}

推薦答案

原文來自 http://paul.luminos.nl/update/471:

CrimsonBase 網(wǎng)站通過一個(gè)強(qiáng)大的 PHP 腳本來驗(yàn)證下載，類似于 Andrew Johnson 發(fā)布的腳本在 他關(guān)于 PHP 控制的文件下載的文章中.

The CrimsonBase website verifies downloads by passing them through a robust PHP script similar to the one published by Andrew Johnson in his article about PHP-controlled file downloads.

Andrew 在文章末尾發(fā)表了一個(gè)非常重要的評(píng)論:

Andrew makes a very important comment at the end of the article:

"如果您使用 Zlib、mod_deflate 等壓縮文件，則 Content-Length 標(biāo)頭將不準(zhǔn)確，因此您最終會(huì)看到未知大小"和剩余時(shí)間未知"下載文件時(shí)."

"If you compress files with Zlib, mod_deflate and so on the Content-Length header won't be accurate so you'll end up seeing "Unknown size" and "Unknown time remaining" when downloading files."

我想強(qiáng)調(diào)一點(diǎn):如果您的瀏覽器似乎沒有遵守由您的 PHP 腳本生成的標(biāo)頭——尤其是 Content-Length——很可能是 Apache 的 mod_deflate 擴(kuò)展已啟用.

I would like to stress this: if your browser doesn't appear to be obeying the headers generated by your PHP script—especially Content-Length—it is fairly likely that Apache's mod_deflate extension is enabled.

您可以使用適用的 .htaccess 文件中的以下行輕松為單個(gè)腳本禁用它:

You can easily disable it for a single script using the following line in an applicable .htaccess file:

SetEnvIfNoCase Request_URI ^/download.php no-gzip dont-vary

此處假定 download.php 位于服務(wù)器根目錄路徑中的下載腳本中(例如 www.crimsonbase.com/download.php).(那是因?yàn)檎齽t表達(dá)式是^/download.php.)

where download.php is here assumed to be in the download script located in the server's root directory path (e.g. www.crimsonbase.com/download.php). (That's because the regular expression is ^/download.php.)

這篇關(guān)于使用 PHP 下載腳本發(fā)送正確的文件大小的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！