附件下载显示进度条

function downloadFileByUrl() {
    var url = '/api/common/downloadFile?xxxx.srt'
    fetch(url, {
        method: 'GET',
        cache: 'no-cache'
    }).then(res => {
        const fileStream = streamSaver.createWriteStream('文件名.mp4', {
            size: res.headers.get("content-length")
        })
        const readableStream = res.body
        // more optimized
        if (window.WritableStream && readableStream.pipeTo) {
            return readableStream.pipeTo(fileStream)
                .then(() => console.log('done writing'))
        }
        window.writer = fileStream.getWriter()

        const reader = res.body.getReader()
        const pump = () => reader.read()
            .then(res => res.done
                ? window.writer.close()
                : window.writer.write(res.value).then(pump))

        pump()
    })
}

<script src="@Url.Content("~/")Static/js/streamSaver.js"></script>

//if you decide to host mitm + sw yourself
streamSaver.mitm ='https://example.com/custom_mitm.html'

/// <summary>
/// 下载附件
/// </summary>
/// <param name="id">附件ID</param>
/// <returns></returns>
[HttpGet, Route("api/file/download"), AllowAnonymous]
public HttpResponseMessage Download(Guid id)
{
    HttpResponseMessage res = new HttpResponseMessage(HttpStatusCode.OK);

    //附件路径
    string fileNames= AppendixHelper.GetFileName(id, AppendixFormat.档案原始稿);
    if (fileNames.Count == 0)
    {
        throw new Exception(MessageCode.CM0000);
    }
    else
    {
        res.Content = new StreamContent(new FileStream(fileNames[0], FileMode.Open));
        res.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
    }

    return res;
}

/// <summary>
/// 
/// </summary>
/// <param name="attachmentId"></param>
/// <returns></returns>
[HttpGet, HttpHead, Route("api/downloadT/{attachmentId}"), AllowAnonymous]
public IHttpActionResult DownloadServerT2(Guid? attachmentId)
{
    if (!attachmentId.HasValue)
    {
        return ResponseMessage(new HttpResponseMessage(HttpStatusCode.BadRequest));
    }
    HttpResponseMessage res = new HttpResponseMessage(HttpStatusCode.OK);

   
    var fileLength = 2000;//文件大小
    var fileName = "http://xxxxxx/xxxxxx.pdf";//文件地址

    HttpResponseMessage response = new HttpResponseMessage();
    string MimeType = "application/octet-stream";
    long speed = 1024 * 100;
    long packSize = 1024 * 10;
    int sleep = (int)Math.Ceiling(1000.0 * packSize / speed);//毫秒数：读取下一数据块的时间间隔
    ContentInfo contentInfo = GetContentInfoFromRequest(this.Request, fileLength);
    Action<Stream, HttpContent, TransportContext> pushContentAction = (outputStream, content, context) =>
    {
        try
        {
            int length = Convert.ToInt32((fileLength - 1) - contentInfo.From) + 1;
            while (length > 0 && packSize > 0)
            {
                WebClient wc = new WebClient();
                wc.BaseAddress = fileName;
                byte[] fdfs;
                fdfs = wc.DownloadData(wc.BaseAddress);

                outputStream.Write(fdfs, 0, fdfs.Length);
                contentInfo.From = contentInfo.From + fdfs.Length;
                length -= fdfs.Length;
                if (sleep > 1)
                {
                    Thread.Sleep(sleep);
                }
            }
        }
        catch (HttpException ex)
        {
            throw ex;
        }
        finally
        {
            outputStream.Close();
        }
    };
    response.Content = new PushStreamContent(pushContentAction, new MediaTypeHeaderValue(MimeType));
    var browser = String.Empty;
    if (Request.Headers.UserAgent != null)
    {
        browser = Request.Headers.UserAgent.ToString().ToUpper();
    }
    response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") // 设置头部其他内容特性, 文件名
    {
        FileName = browser.Contains("FIREFOX") ? fileName : HttpUtility.UrlEncode(fileName)
    };

    return ResponseMessage(response);
}

/// <summary>
/// 
/// </summary>
/// <param name="FileName">文件名称</param>
/// <param name="FilePath">文件路径</param>
public void DownLoad(string FileName, string FilePath)
{
    string result = string.Empty;
    WebClient wc = new WebClient();
    wc.BaseAddress = FilePath;
    byte[] bytes;
    bytes = wc.DownloadData(wc.BaseAddress);
    Response.ContentType = "application/octet-stream";
    Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}", HttpUtility.UrlEncode(
    FileName), System.Text.Encoding.UTF8));
    MemoryStream ms = new MemoryStream(bytes); 
    ms.WriteTo(Response.OutputStream); 
    ms.Dispose(); 
    ms.Close();
}

/// <summary>
/// 下载实时返回下载进度
/// </summary>
/// <param name="URL">下载地址</param>
/// <param name="filename">本地存储地址</param>
public void DownloadFileData2(string URL, string filename)
{
    float percent = 0;
    try
    {
        HttpWebRequest Myrq = (HttpWebRequest)HttpWebRequest.Create(URL);
        HttpWebResponse myrp = (HttpWebResponse)Myrq.GetResponse();
        long totalBytes = myrp.ContentLength, totalDownloadedByte = 0;
        Stream st = myrp.GetResponseStream();


        using (MemoryStream ms = new MemoryStream())
        {
            HttpResponse response = System.Web.HttpContext.Current.Response;
            response.Clear();

            response.Charset = "GB2312";
            response.ContentType = "application/msword";
            byte[] by = new byte[1024];
            int osize = st.Read(by, 0, (int)by.Length);
            while (osize > 0)
            {
                totalDownloadedByte = osize + totalDownloadedByte;
                ms.Write(by, 0, osize);
                osize = st.Read(by, 0, (int)by.Length);
                percent = (float)totalDownloadedByte / (float)totalBytes * 100;//当前位置
            }
            st.Close();
            System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename=" + filename));
            response.ContentEncoding = System.Text.Encoding.Unicode;
            ms.WriteTo(response.OutputStream);
            ms.Close();
        }
        HttpContext.Current.Response.End();

    }
    catch (System.Exception)
    {
        throw;
    }
}

//string fileName = DateTime.Now.ToString("yyyyMMddHHmmss") + ".doc";
                using (MemoryStream ms = new MemoryStream())
                {
                    HttpResponse response = System.Web.HttpContext.Current.Response;
                    response.Clear();

                    response.Charset = "GB2312";
                    response.ContentType = "application/msword";
                    doc.Save(ms, SaveFormat.Doc);
                    System.Web.HttpContext.Current.Response.AddHeader("Content-Disposition", string.Format("attachment; filename=" + filename));
                    response.ContentEncoding = System.Text.Encoding.Unicode;
                    ms.WriteTo(response.OutputStream);
                    ms.Close();
                }
                HttpContext.Current.Response.End();