如何获取上传到服务器的数据百分比

Question

我有一个包含以下参数的模型

 public class FileExchangeDetails
{
    public Guid SenderId { get; set; }
  
    public List<Files> Files { get; set; }

    public Guid Id { get; set; }
}

public class Files
{
    public string FilePath { get; set; }

    public string FileName { get; set; }

    public byte[] FileBytes { get; set; }

    public string FileType { get; set; }
}

我正在使用FileExchangeDetails 发送文件数据（图像或文件）

 public static async Task<string> PostFilesToToApi(string apiUrl, FileExchangeDetails exchangeDetails)
    {
        

        try
        {
            
            using (var httpreqclient = new httpclient())
            {
                httpreqclient.baseaddress = new uri(string.format(apiurls.weburl, application.current.properties["currentsitename"]));

                httpreqclient.defaultrequestheaders.add("authorization", "bearer " + applicationcontext.accesstoken);

                httpreqclient.defaultrequestheaders.accept.add(new mediatypewithqualityheadervalue("application/json"));//accept header

                var content = jsonconvert.serializeobject(exchangedetails, formatting.none);

                var stringcontentinput = new stringcontent(content, encoding.utf8, "application/json");

                var response = await httpreqclient.postasync(new uri(string.format(apiurls.weburl, application.current.properties["currentsitename"]) + apiurl), stringcontentinput);

                var stringasync = await response.content.readasstringasync();

                if (response.issuccessstatuscode)
                {
                    var responsejson = stringasync;

                    return responsejson;
                }
            }
        }
        catch (Exception exception)
        {
            LoggingManager.Error(exception, "PostFilesToToApi", "ApiWrapper");
        }

        return null;
    }

功能上一切正常，但现在我需要在上传到服务器时显示文件上传的百分比。

我对 web 客户端几乎没有指导方针，但参数只有字节 [] 或字符串。

如何使用 httpclient 获取该 % 数据。有人可以帮我解决这个问题吗？

Answer 1

您可以创建一个自定义 HttpContent，如下所示

internal class ProgressableStreamContent : HttpContent
{
    private const int defaultBufferSize = 4096;

    private Stream content;
    private int bufferSize;
    private bool contentConsumed;
    private Download downloader;

    public ProgressableStreamContent(Stream content, Download downloader) : this(content, defaultBufferSize, downloader) {}

    public ProgressableStreamContent(Stream content, int bufferSize, Download downloader)
    {
        if(content == null)
        {
            throw new ArgumentNullException("content");
        }
        if(bufferSize <= 0)
        {
            throw new ArgumentOutOfRangeException("bufferSize");
        }

        this.content = content;
        this.bufferSize = bufferSize;
        this.downloader = downloader;
    }

    protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
    {
        Contract.Assert(stream != null);

        PrepareContent();

        return Task.Run(() =>
        {
            var buffer = new Byte[this.bufferSize];
            var size = content.Length;
            var uploaded = 0;

            downloader.ChangeState(DownloadState.PendingUpload);

            using(content) while(true)
            {
                var length = content.Read(buffer, 0, buffer.Length);
                if(length <= 0) break;

                downloader.Uploaded = uploaded += length;

                stream.Write(buffer, 0, length);

                downloader.ChangeState(DownloadState.Uploading);
            }

            downloader.ChangeState(DownloadState.PendingResponse);
        });
    }

    protected override bool TryComputeLength(out long length)
    {
        length = content.Length;
        return true;
    }

    protected override void Dispose(bool disposing)
    {
        if(disposing)
        {
            content.Dispose();
        }
        base.Dispose(disposing);
    }


    private void PrepareContent()
    {
        if(contentConsumed)
        {
            // If the content needs to be written to a target stream a 2nd time, then the stream must support
            // seeking (e.g. a FileStream), otherwise the stream can't be copied a second time to a target 
            // stream (e.g. a NetworkStream).
            if(content.CanSeek)
            {
                content.Position = 0;
            }
            else
            {
                throw new InvalidOperationException("SR.net_http_content_stream_already_read");
            }
        }

        contentConsumed = true;
    }
}

参考：C#: HttpClient, File upload progress when uploading multiple file as MultipartFormDataContent