http ContentLength 为0 下载问题

 如图 通过http 下载某个东西 ，    WebResponse response = request.GetResponse(); response 调试如图

ContentLength 为0   但Content-Range 是有值的 导致下载的视频是0字节

修改后的代码：

 public static int GetTotalSize(string url)
        {
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
            request.CookieContainer = BaseService.CookiesContainer;
            WebResponse response = request.GetResponse();
            int len = Int32.Parse(response.Headers["Content-Range"].ToString().Split(new char[] { '/' })[1]);
            return len;
        }

        public static byte[] SendRangeGetRequest(string url)
        {
            try
            {
                int len = GetTotalSize(url);
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                request.Method = "get";
                request.AddRange("bytes", 0, len);  //这部是关键 加上它,response 的ContentLength 就有值了

                if (CookiesContainer == null)
                {
                    CookiesContainer = new CookieContainer();
                }

                request.CookieContainer = CookiesContainer;  //启用cookie

                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                Stream response_stream = response.GetResponseStream();

                int count = (int)response.ContentLength;
                int offset = 0;
                byte[] buf = new byte[count];
                while (count > 0)  //读取返回数据
                {
                    int n = response_stream.Read(buf, offset, count);
                    if (n == 0) break;
                    count -= n;
                    offset += n;
                }
                return buf;
            }
            catch
            {
                return null;
            }
        }

最后   File.WriteAllBytes(savePath, bytes);  就能下载到本地了