HttpClient 上传/下载文件计算文件传输进度

1.使用ProgressMessageHandler 获取进度

using namespace System.Net.Http;

HttpClientHandler hand = new HttpClientHandler();
ProgressMessageHandler processMessageHander = new ProgressMessageHandler(hand);
HttpClient localHttpClient = new HttpClient(processMessageHander);

processMessageHander.HttpSendProgress += (sender, e2) =>
{
    int num = e2.ProgressPercentage; //you can use HttpProgressEventArgs e
    worker.ReportProgress(num);
};

var resp = await localHttpClient.SendAsync(httpRequestMessage);
  Stream stream = await resp.Content.ReadAsStreamAsync();

2. 在已知要下载的文件大小的情况下，可以计算获取进度

var resp = await _client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead);
using (Stream stream = await resp.Content.ReadAsStreamAsync(),
        fs = new FileStream(downloadPath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite, , true))
{
    var totalRead = 0L;
    var buffer = new byte[];
    var isMoreToRead = true;
    do
    {
        if (worker.CancellationPending)
        {
            e.Cancel = true;
            return false;
        }

        var read = await stream.ReadAsync(buffer, , buffer.Length);
        if (read == )
        {
            isMoreToRead = false;
        }
        else
        {
            await fs.WriteAsync(buffer, , read);
            totalRead += read;

            int percentComplete = (int)((float)totalRead / (float)fileSize * );
            worker.ReportProgress(percentComplete);
        }
    }
    while (isMoreToRead);
}