C#:HttpClient，上传多个文件作为 MultipartFormDataContent 时的文件上传进度 [英] C#: HttpClient, File upload progress when uploading multiple file as MultipartFormDataContent
问题描述
我正在使用此代码上传多个文件，并且运行良好.它使用现代httpclient 库.
I'm using this code to upload multiple files and it working very well. It uses modernhttpclient library.
public async Task<string> PostImages (int platform, string url, List<byte []> imageList)
{
try {
int count = 1;
var requestContent = new MultipartFormDataContent ();
foreach (var image in imageList) {
var imageContent = new ByteArrayContent (image);
imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse ("image/jpeg");
requestContent.Add (imageContent, "image" + count, "image.jpg");
count++;
}
var cookieHandler = new NativeCookieHandler ();
var messageHandler = new NativeMessageHandler (false, false, cookieHandler);
cookieHandler.SetCookies (cookies);
using (var client = new HttpClient (messageHandler)) {
client.DefaultRequestHeaders.TryAddWithoutValidation ("User-Agent", GetUserAgent (platform));
using (var r = await client.PostAsync (url, requestContent)) {
string result = await r.Content.ReadAsStringAsync ();
System.Diagnostics.Debug.WriteLine ("PostAsync: " + result);
return result;
}
}
} catch (Exception e) {
System.Diagnostics.Debug.WriteLine (e.Message);
return null;
}
}
现在我需要上传文件时的进度.我在谷歌搜索，发现我需要使用 ProgressStreamContent
Now I need the progress when uploading the files. I searched in google and found I need to use ProgressStreamContent
https://github.com/paulcbetts/ModernHttpClient/issues/80
由于 ProgressStreamContent 包含一个接受流的构造函数，我将 MultipartFormDataContent 转换为流并在其构造函数中使用它.但是，它不起作用.上传失败.我认为这是因为它是所有文件的流，这不是我的后端所期望的.
Since ProgressStreamContent contains a constructor that takes a stream, I converted the MultipartFormDataContent to stream and used it in its constructor. But, its not working. Upload fails. I think its because it is a stream of all the files together which is not what my back end is expecting.
public async Task<string> PostImages (int platform, string url, List<byte []> imageList)
{
try {
int count = 1;
var requestContent = new MultipartFormDataContent ();
// here you can specify boundary if you need---^
foreach (var image in imageList) {
var imageContent = new ByteArrayContent (image);
imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse ("image/jpeg");
requestContent.Add (imageContent, "image" + count, "image.jpg");
count++;
}
var cookieHandler = new NativeCookieHandler ();
var messageHandler = new NativeMessageHandler (false, false, cookieHandler);
cookieHandler.SetCookies (RestApiPaths.cookies);
var stream = await requestContent.ReadAsStreamAsync ();
var client = new HttpClient (messageHandler);
client.DefaultRequestHeaders.TryAddWithoutValidation ("User-Agent", RestApiPaths.GetUserAgent (platform));
var request = new HttpRequestMessage (HttpMethod.Post, url);
var progressContent = new ProgressStreamContent (stream, 4096);
progressContent.Progress = (bytes, totalBytes, totalBytesExpected) => {
Console.WriteLine ("Uploading {0}/{1}", totalBytes, totalBytesExpected);
};
request.Content = progressContent;
var response = await client.SendAsync (request);
string result = await response.Content.ReadAsStringAsync ();
System.Diagnostics.Debug.WriteLine ("PostAsync: " + result);
return result;
} catch (Exception e) {
System.Diagnostics.Debug.WriteLine (e.Message);
return null;
}
}
我应该在这里做什么才能让它工作?任何帮助表示赞赏
What should I do here to get this working? Any help is appreciated
推荐答案
我有一个 ProgressableStreamContent 的工作版本.请注意，我在构造函数中添加标头，这是原始 ProgressStreamContent 中的一个错误，它不添加标头！！
I have a working version of ProgressableStreamContent. Please note, I am adding headers in the constructor, this is a bug in original ProgressStreamContent that it does not add headers !!
internal class ProgressableStreamContent : HttpContent
{
/// <summary>
/// Lets keep buffer of 20kb
/// </summary>
private const int defaultBufferSize = 5*4096;
private HttpContent content;
private int bufferSize;
//private bool contentConsumed;
private Action<long,long> progress;
public ProgressableStreamContent(HttpContent content, Action<long,long> progress) : this(content, defaultBufferSize, progress) { }
public ProgressableStreamContent(HttpContent content, int bufferSize, Action<long,long> progress)
{
if (content == null)
{
throw new ArgumentNullException("content");
}
if (bufferSize <= 0)
{
throw new ArgumentOutOfRangeException("bufferSize");
}
this.content = content;
this.bufferSize = bufferSize;
this.progress = progress;
foreach (var h in content.Headers) {
this.Headers.Add(h.Key,h.Value);
}
}
protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
return Task.Run(async () =>
{
var buffer = new Byte[this.bufferSize];
long size;
TryComputeLength(out size);
var uploaded = 0;
using (var sinput = await content.ReadAsStreamAsync())
{
while (true)
{
var length = sinput.Read(buffer, 0, buffer.Length);
if (length <= 0) break;
//downloader.Uploaded = uploaded += length;
uploaded += length;
progress?.Invoke(uploaded, size);
//System.Diagnostics.Debug.WriteLine($"Bytes sent {uploaded} of {size}");
stream.Write(buffer, 0, length);
stream.Flush();
}
}
stream.Flush();
});
}
protected override bool TryComputeLength(out long length)
{
length = content.Headers.ContentLength.GetValueOrDefault();
return true;
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
content.Dispose();
}
base.Dispose(disposing);
}
}
另请注意，它需要 HttpContent，而不是流.
Also note, it expects HttpContent, not stream.
这就是你可以使用它的方式.
This is how you can use it.
var progressContent = new ProgressableStreamContent (
requestContent,
4096,
(sent,total) => {
Console.WriteLine ("Uploading {0}/{1}", sent, total);
});
这篇关于C#:HttpClient，上传多个文件作为 MultipartFormDataContent 时的文件上传进度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
