解决IOS通过HTML5播放Video或者Audio直接输出数据的问题

大家都知道HTML5通过Video或者Audio标签的src属性可以直接播放网络路径的视频或者音频，IOS对于直接读取文件是没问题的，但是如果需要输出数据的方式读取就有问题，是打不开文件的，为了完美支持html5的视频播放，必须支持byte-range请求。因为html5播放视频之前会发送一个只需文件少数字节的请求，确认服务端是否支持byte-range请求，支持才会继续发送请求剩余的文件数据。

下载代码：

private void RangeDownload(string fullpath, HttpContext context)
    {
        long size, start, end, length, fp = 0;
        using (StreamReader reader = new StreamReader(fullpath))
        {
            size = reader.BaseStream.Length;
            start = 0;
            end = size - 1;
            length = size;
            context.Response.AddHeader("Accept-Ranges", "0-" + size);

            if (!String.IsNullOrEmpty(context.Request.ServerVariables["HTTP_RANGE"]))
            {
                long anotherStart = start;
                long anotherEnd = end;
                string[] arr_split = context.Request.ServerVariables["HTTP_RANGE"].Split(new char[] { Convert.ToChar("=") });
                string range = arr_split[1];

                // Make sure the client hasn't sent us a multibyte range
                if (range.IndexOf(",") > -1)
                {
                    context.Response.AddHeader("Content-Range", "bytes " + start + "-" + end + "/" + size);
                    throw new HttpException(416, "Requested Range Not Satisfiable");
                }
                
                if (range.StartsWith("-"))
                {
                    // The n-number of the last bytes is requested
                    anotherStart = size - Convert.ToInt64(range.Substring(1));
                }
                else
                {
                    arr_split = range.Split(new char[] { Convert.ToChar("-") });
                    anotherStart = Convert.ToInt64(arr_split[0]);
                    long temp = 0;
                    anotherEnd = (arr_split.Length > 1 && Int64.TryParse(arr_split[1].ToString(), out temp)) ? Convert.ToInt64(arr_split[1]) : size;
                }

                anotherEnd = (anotherEnd > end) ? end : anotherEnd;

                if (anotherStart > anotherEnd || anotherStart > size - 1 || anotherEnd >= size)
                {
                    context.Response.AddHeader("Content-Range", "bytes " + start + "-" + end + "/" + size);
                    throw new HttpException(416, "Requested Range Not Satisfiable");
                }
                start = anotherStart;
                end = anotherEnd;

                length = end - start + 1; // Calculate new content length
                fp = reader.BaseStream.Seek(start, SeekOrigin.Begin);
                context.Response.StatusCode = 206;
            }
        }
        // Notify the client the byte range we'll be outputting
        context.Response.AddHeader("Content-Range", "bytes " + start + "-" + end + "/" + size);
        context.Response.AddHeader("Content-Length", length.ToString());
        // Start buffered download
        context.Response.WriteFile(fullpath, fp, length);
        //context.Response.End();
    }

调用：

if (System.IO.File.Exists(fullPath))
            {
                HttpContext context = System.Web.HttpContext.Current;
                
                string mimetype = GetContentType(path);
                if (System.IO.File.Exists(fullPath))
                {
                    context.Response.ContentType = mimetype;
                    if (!String.IsNullOrEmpty(context.Request.ServerVariables["HTTP_RANGE"]))
                    {
                        //request for chunk
                        RangeDownload(fullPath, context);
                    }
                    else
                    {
                        //ask for all 
                        long fileLength = File.OpenRead(fullPath).Length;
                        context.Response.AddHeader("Content-Length", fileLength.ToString());
                        context.Response.WriteFile(fullPath);
                    }
                }
                else
                {
                    throw new HttpException(404, "Video Not Found Path:" + fullPath);
                }
            }