上传之前，httpclient读取整个文件.UWP

Question

我正在制作一个将文件上传到Facebook的UWP应用并报告进度。

我的自定义httpcontent uploadwithprogresshttpcontent：

 class UploadWithProgressHttpContent : HttpContent
{
    private readonly IProgress<OperationProgress> _progress;
    private readonly OperationProgress _data;
    private readonly Stream _file;
    private readonly int _bufferSize;
    private readonly CancellationToken _token;
    public UploadWithProgressHttpContent(
        IProgress<OperationProgress> progress,
    OperationProgress data,
    Stream file,
    int bufferSize,
    CancellationToken token)
{
    _progress = progress;
    _data = data;
    _file = file;
    _bufferSize = bufferSize;
    _token = token;
}

protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
    return CopyStreamWithProgress(_file, stream, _progress, _token, _data, _bufferSize);
}
public static async Task<Stream> CopyStreamWithProgress(
    Stream source,
    Stream destination,
    IProgress<OperationProgress> progress,
    CancellationToken token,
    OperationProgress progressData,
    int bufferSize
    )
{
    int read, offset = 0;
    var buffer = new byte[bufferSize];
    using (source)
    {
        do
        {
            read = await source.ReadAsync(buffer, 0, bufferSize, token);
            await destination.WriteAsync(buffer, 0, read, token);
            offset += read;
            progressData.CurrentSize = offset;
            progress.Report(progressData);
        } while (read != 0);
    }
    return destination;
}
}

我正在经历的（使用提琴手）是在上传开始之前将整个文件放在内存中（我的进度仪表在上传之前达到100％）。

我确实尝试将TransferEncodingChunked设置为true，并设置文件内容长度，但仍然存在。

上传源在PCL内部（如果很重要）。我正在使用System.Net.Http的最新版本。如果需要

感谢您的任何帮助。

编辑：添加httpclient用法：

public async Task<T> Upload<T>(Stream fileStream, string fileName)
{
    var handler = new HttpClientHandler();

    var cli = new HttpClient(handler);
    foreach (var header in Headers)
    {
        cli.DefaultRequestHeaders.Add(header.Key, header.Value);
    }
    var parameters = new MultipartFormDataContent();
    foreach (var parameter in Parameters)
    {
        parameters.Add(new StringContent(parameter.Value), parameter.Key);
    }
    if (fileStream != null)
    {
        var fileContent = new UploadWithProgressHttpContent(ProgressOperation, ProgressData, fileStream,
            _chunkBufferSize, Token, fileStream.Length);
        fileContent.Headers.ContentType = new MediaTypeHeaderValue(MimeTypeHelper.GetMimeType(fileName));
        fileContent.Headers.ContentDisposition = new ContentDispositionHeaderValue(StreamParamName);
        fileContent.Headers.ContentDisposition.FileName = fileName;
        fileContent.Headers.ContentLength = fileStream.Length;
        parameters.Add(fileContent, StreamParamName);
    }
    var req = new HttpRequestMessage(method, Path) { Content = parameters };
    if (fileStream != null)
        req.Headers.TransferEncodingChunked = true;

    var completionOption = HttpCompletionOption.ResponseContentRead;

    var resp = await cli.SendAsync(req, completionOption, Token).ConfigureAwait(false);
    return await DeserializeObject<T>(resp);
}

Answer 1

您有与量子力学相同的问题 - 观察到观察到的行为。提琴手不支持请求流 - 请参阅提琴手使httpwebrequest/httpclient行为出乎意料和http://www.telerik.com/forums/is-it-possible-to-not-buffer-requests

使用Wireshark我可以看到块。

Answer 2

在这个问题上浪费了几个小时后，它是一个httpclient实现问题。因此，如果您想向服务器流动内容（并报告进度），最好的选择是使用StreamContent并装饰读取以报告进度。

注意：这对于System.Net.Http和2.2.29 Microsoft.Net.Http nugget软件包的4.3.1版本