使用Node.js实现HTTP 206内容分片的教程

// Indicate the current range.
  responseHeaders['Content-Range'] = 'bytes ' + start + '-' + end + '/' + stat.size;
  responseHeaders['Content-Length'] = start == end ? 0 : (end - start + 1);
  responseHeaders['Content-Type'] = getMimeNameFromExt(path.extname(filename));
  responseHeaders['Accept-Ranges'] = 'bytes';
  responseHeaders['Cache-Control'] = 'no-cache';
  // Return the 206 'Partial Content'.
  sendResponse(response, 206,
    responseHeaders, fs.createReadStream(filename, { start: start, end: end }));

下面是完整的 httpListener() 回调函数.

function httpListener(request, response) {
  // We will only accept 'GET' method. Otherwise will return 405 'Method Not Allowed'.
  if (request.method != 'GET') {
    sendResponse(response, 405, { 'Allow': 'GET' }, null);
    return null;
  }
  var filename =
    initFolder + url.parse(request.url, true, true).pathname.split('/').join(path.sep);
  // Check if file exists. If not, will return the 404 'Not Found'.
  if (!fs.existsSync(filename)) {
    sendResponse(response, 404, null, null);
    return null;
  }
  var responseHeaders = {};
  var stat = fs.statSync(filename);
  var rangeRequest = readRangeHeader(request.headers['range'], stat.size);
  // If 'Range' header exists, we will parse it with Regular Expression.
  if (rangeRequest == null) {
    responseHeaders['Content-Type'] = getMimeNameFromExt(path.extname(filename));
    responseHeaders['Content-Length'] = stat.size; // File size.
    responseHeaders['Accept-Ranges'] = 'bytes';
    // If not, will return file directly.
    sendResponse(response, 200, responseHeaders, fs.createReadStream(filename));
    return null;
  }
  var start = rangeRequest.Start;
  var end = rangeRequest.End;
  // If the range can't be fulfilled.
  if (start >= stat.size || end >= stat.size) {
    // Indicate the acceptable range.
    responseHeaders['Content-Range'] = 'bytes */' + stat.size; // File size.
    // Return the 416 'Requested Range Not Satisfiable'.
    sendResponse(response, 416, responseHeaders, null);
    return null;
  }
  // Indicate the current range.
  responseHeaders['Content-Range'] = 'bytes ' + start + '-' + end + '/' + stat.size;
  responseHeaders['Content-Length'] = start == end ? 0 : (end - start + 1);
  responseHeaders['Content-Type'] = getMimeNameFromExt(path.extname(filename));
  responseHeaders['Accept-Ranges'] = 'bytes';
  responseHeaders['Cache-Control'] = 'no-cache';
  // Return the 206 'Partial Content'.
  sendResponse(response, 206,
    responseHeaders, fs.createReadStream(filename, { start: start, end: end }));
}

测试实现

我们怎么来测试我们的代码呢？就像在介绍中提到的，部分正文最常用的场景是流和播放视频。所以我们创建了一个ID为mainPlayer并包含一个<source/>标签的<video/>。函数onLoad()将在mainPlayer预读取当前视频的元数据时被触发，这用于检查在URL中是否有数字参数，如果有，mainPlayer将跳到指定的时间点。