如何计算与HttpClient的PostAsync进展？

本文介绍了如何计算与HttpClient的PostAsync进展？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

在我的Windows Store应用（C＃）我需要上传 MultipartFormDataContent （一些字符串的内容和一些文件），以服务器和响应得到一个巨大的文件。这个问题 - 我不能使用 BackgroundDownloaders 为。我只能用一个请求为

In my Windows Store App (c#) I need to upload MultipartFormDataContent (some strings content and some files) to server and get a huge file at response. The problem - I can't use BackgroundDownloaders for that. I can only use one request for that.

我用 HttpClient.PostAsync 方法：

using (var client = new HttpClient(httpClientHandler)) { using (var content = new MultipartFormDataContent()) { content.Add(...); // prepare all strings and files content try { using (var response = await client.PostAsync(url, content)) { if (response.StatusCode == HttpStatusCode.OK) { var inputBytes = await response.Content.ReadAsByteArrayAsync(); // some operations with inputBytes } ...... } } } }

我的问题是：我如何计算这个操作的进展如何？

My question is: How can I calculate progress of this operation?

注意： - Windows 8中，我不能使用 Windows.Web.Http.HttpClient <我的目标/ code>（最低支持的客户端Windows 8.1）。只有 System.Net.Http.HttpClient

Note: My target - Windows 8. And I can't use Windows.Web.Http.HttpClient (Minimum supported client Windows 8.1). Only System.Net.Http.HttpClient

推荐答案

我面临同样的问题。我通过实现自定义的固定它 HttpContent 。我使用这个对象来跟踪上传进度百分比，你可以添加一个事件来，听它。你应该定义 SerializeToStreamAsync 法

I faced same issue. I fixed it by implementing custom HttpContent. I use this object to track percentage of upload progress, you can add an event to and listen it. You should customize SerializeToStreamAsync method.

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_http_content_stream_already_read"); } } contentConsumed = true; } }