在这里找到有关此的一些信息：
这是（我发现）获取远程文件大小的最佳方法。请注意，HEAD请求不会获取请求的实际主体，它们只是检索标头。因此，对100MB的资源进行HEAD请求所花费的时间与对1KB的资源进行HEAD请求所花费的时间相同。
<?phpfunction 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_pres 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" );
