range协议用途：一般是用在断点续传的时候，但是实际的用户很大，例如你的web server需要输出一个大文件，那么用range可以分段输出，缓解压力。同时在提供音乐视频等服务时可以缓冲下载，如果用户中途关闭，可以节约网络带宽。
<?php // 文件名 $filename = $_GET ['filename']; // 文件路径 $location = 'media/' . $filename; // 后缀 $extension = substr ( strrchr ( $filename, '.' ), 1 ); if ($extension == "mp3") { $mimeType = "audio/mpeg"; } else if ($extension == "ogg") { $mimeType = "audio/ogg"; } if (! file_exists ( $location )) { header ( "HTTP/1.1 404 Not Found" ); return; } $size = filesize ( $location ); $time = date ( 'r', filemtime ( $location ) ); $fm = @fopen ( $location, 'rb' ); if (! $fm) { header ( "HTTP/1.1 505 Internal server error" ); return; } $begin = 0; $end = $size - 1; if (isset ( $_SERVER ['HTTP_RANGE'] )) { if (preg_match ( '/bytes=\h*(\d+)-(\d*)[\D.*]?/i', $_SERVER ['HTTP_RANGE'], $matches )) { // 读取文件，起始节点 $begin = intval ( $matches [1] ); // 读取文件，结束节点 if (! empty ( $matches [2] )) { $end = intval ( $matches [2] ); } } } if (isset ( $_SERVER ['HTTP_RANGE'] )) { header ( 'HTTP/1.1 206 Partial Content' ); } else { header ( 'HTTP/1.1 200 OK' ); } header ( "Content-Type: $mimeType" ); header ( 'Cache-Control: public, must-revalidate, max-age=0' ); header ( 'Pragma: no-cache' ); header ( 'Accept-Ranges: bytes' ); header ( 'Content-Length:' . (($end - $begin) + 1) ); if (isset ( $_SERVER ['HTTP_RANGE'] )) { header ( "Content-Range: bytes $begin-$end/$size" ); } header ( "Content-Disposition: inline; filename=$filename" ); header ( "Content-Transfer-Encoding: binary" ); header ( "Last-Modified: $time" ); $cur = $begin; // 定位指针 fseek ( $fm, $begin, 0 ); while ( ! feof ( $fm ) && $cur <= $end && (connection_status () == 0) ) { print fread ( $fm, min ( 1024 * 16, ($end - $cur) + 1 ) ); $cur += 1024 * 16; }
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