无需下载文件的远程文件大小

问题描述：

有没有办法获取远程文件的大小http://my_url/my_file.txt 而无需下载文件?

Is there a way to get the size of a remote file http://my_url/my_file.txt without downloading the file?

答

发现了一些关于此的内容这里:

Found something about this here:

这是获得遥控器大小的最佳方法(我发现的)文件.请注意， HEAD 请求不会获取请求的实际正文，他们只是检索标题.所以向资源发出 HEAD 请求即 100MB 将花费与 HEAD 请求相同的时间1KB 的资源.

Here's the best way (that I've found) to get the size of a remote file. Note that HEAD requests don't get the actual body of the request, they just retrieve the headers. So making a HEAD request to a resource that is 100MB will take the same amount of time as a HEAD request to a resource that is 1KB.

<?php
/**
 * Returns the size of a file without downloading it, or -1 if the file
 * size could not be determined.
 *
 * @param $url - The location of the remote file to download. Cannot
 * be null or empty.
 *
 * @return The size of the file referenced by $url, or -1 if the size
 * could not be determined.
 */
function curl_get_file_size( $url ) {
  // Assume failure.
  $result = -1;

  $curl = curl_init( $url );

  // Issue a HEAD request and follow any redirects.
  curl_setopt( $curl, CURLOPT_NOBODY, true );
  curl_setopt( $curl, CURLOPT_HEADER, true );
  curl_setopt( $curl, CURLOPT_RETURNTRANSFER, true );
  curl_setopt( $curl, CURLOPT_FOLLOWLOCATION, true );
  curl_setopt( $curl, CURLOPT_USERAGENT, get_user_agent_string() );

  $data = curl_exec( $curl );
  curl_close( $curl );

  if( $data ) {
    $content_length = "unknown";
    $status = "unknown";

    if( preg_match( "/^HTTP/1.[01] (ddd)/", $data, $matches ) ) {
      $status = (int)$matches[1];
    }

    if( preg_match( "/Content-Length: (d+)/", $data, $matches ) ) {
      $content_length = (int)$matches[1];
    }

    // http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
    if( $status == 200 || ($status > 300 && $status <= 308) ) {
      $result = $content_length;
    }
  }

  return $result;
}
?>

用法:

$file_size = curl_get_file_size( "http://stackoverflow.com/questions/2602612/php-remote-file-size-without-downloading-file" );

无需下载文件的远程文件大小

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