c# HttpClient上传和下载的进度显示问题

WebClient中有DownloadProgressChangedEventHandler等事件可以响应http请求(或者其他web请求)的进度。

在c# 5.0中,HttpClient的函数都是以Task异步函数存在，没有事件可以回调显示上传或下载的进度。

我找了很久，终于发现ProgressMessageHandler 可以解决这个问题，链接：http://msdn.microsoft.com/en-us/library/system.net.http.handlers.progressmessagehandler(v=vs.108).aspx

具体示例代码

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

HttpRequestMessage httpRequestMessage = new HttpRequestMessage();

httpRequestMessage.Method = HttpMethod.Put;
httpRequestMessage.Content = new StreamContent(content);

//for upload

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


};

//for download

// processMessageHander.HttpReceiveProgress += (sender, e) =>
// {
// int num = e.ProgressPercentage;

// };

HttpResponseMessage test = await localHttpClient.SendAsync(httpRequestMessage);

// dispose the resource