C＃HttpClient 4.5分段/表单数据上传

有谁知道如何使用 HttpClient在.Net 4.5中使用multipart/form-data上传功能？

我在互联网上找不到任何示例。

我的结果看起来像这样：

public static async Task<string> Upload(byte[] image)
{
     using (var client = new HttpClient())
     {
         using (var content =
             new MultipartFormDataContent("Upload----" + DateTime.Now.ToString(CultureInfo.InvariantCulture)))
         {
             content.Add(new StreamContent(new MemoryStream(image)), "bilddatei", "upload.jpg");

              using (
                 var message =
                     await client.PostAsync("http://www.directupload.net/index.php?mode=upload", content))
              {
                  var input = await message.Content.ReadAsStringAsync();

                  return !string.IsNullOrWhiteSpace(input) ? Regex.Match(input, @"http://\w*\.directupload\.net/images/\d*/\w*\.[a-z]{3}").Value : null;
              }
          }
     }
}

它或多或少像这样工作（例如使用图像/ jpg文件的示例）：

async public Task<HttpResponseMessage> UploadImage(string url, byte[] ImageData)
{
    var requestContent = new MultipartFormDataContent(); 
    //    here you can specify boundary if you need---^
    var imageContent = new ByteArrayContent(ImageData);
    imageContent.Headers.ContentType = 
        MediaTypeHeaderValue.Parse("image/jpeg");

    requestContent.Add(imageContent, "image", "image.jpg");

    return await client.PostAsync(url, requestContent);
}

（您可以随意使用requestContent.Add()，看看HttpContent后代，以查看可用的类型）

完成后，你会发现响应里面的内容HttpResponseMessage.Content，您可以用消耗HttpContent.ReadAs*Async。

这是一个如何使用MultipartFormDataContent通过HTTPClient发布字符串和文件流的示例。需要为每个HTTPContent指定Content-Disposition和Content-Type：

这是我的例子。希望能帮助到你：

private static void Upload()
{
    using (var client = new HttpClient())
    {
        client.DefaultRequestHeaders.Add("User-Agent", "CBS Brightcove API Service");

        using (var content = new MultipartFormDataContent())
        {
            var path = @"C:\B2BAssetRoot\files\596086\596086.1.mp4";

            string assetName = Path.GetFileName(path);

            var request = new HTTPBrightCoveRequest()
                {
                    Method = "create_video",
                    Parameters = new Params()
                        {
                            CreateMultipleRenditions = "true",
                            EncodeTo = EncodeTo.Mp4.ToString().ToUpper(),
                            Token = "x8sLalfXacgn-4CzhTBm7uaCxVAPjvKqTf1oXpwLVYYoCkejZUsYtg..",
                            Video = new Video()
                                {
                                    Name = assetName,
                                    ReferenceId = Guid.NewGuid().ToString(),
                                    ShortDescription = assetName
                                }
                        }
                };

            //Content-Disposition: form-data; name="json"
            var stringContent = new StringContent(JsonConvert.SerializeObject(request));
            stringContent.Headers.Add("Content-Disposition", "form-data; name=\"json\"");
            content.Add(stringContent, "json");

            FileStream fs = File.OpenRead(path);

            var streamContent = new StreamContent(fs);
            streamContent.Headers.Add("Content-Type", "application/octet-stream");
            //Content-Disposition: form-data; name="file"; filename="C:\B2BAssetRoot\files\596090\596090.1.mp4";
            streamContent.Headers.Add("Content-Disposition", "form-data; name=\"file\"; filename=\"" + Path.GetFileName(path) + "\"");
            content.Add(streamContent, "file", Path.GetFileName(path));

            //content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");

            Task<HttpResponseMessage> message = client.PostAsync("http://api.brightcove.com/services/post", content);

            var input = message.Result.Content.ReadAsStringAsync();
            Console.WriteLine(input.Result);
            Console.Read();
        }
    }
}

这是有关如何使用HttpClient上载的另一个示例multipart/form-data。

它将文件上传到REST API，并包括文件本身（例如JPG）和其他API参数。该文件是通过本地磁盘直接上传的FileStream。

有关完整的示例，请参见此处，其中包括其他特定于API的逻辑。

public static async Task UploadFileAsync(string token, string path, string channels)
{
    // we need to send a request with multipart/form-data
    var multiForm = new MultipartFormDataContent();

    // add API method parameters
    multiForm.Add(new StringContent(token), "token");
    multiForm.Add(new StringContent(channels), "channels");

    // add file and directly upload it
    FileStream fs = File.OpenRead(path);
    multiForm.Add(new StreamContent(fs), "file", Path.GetFileName(path));

    // send request to API
    var url = "https://slack.com/api/files.upload";
    var response = await client.PostAsync(url, multiForm);
}

试试这个对我有用。

private static async Task<object> Upload(string actionUrl)
{
    Image newImage = Image.FromFile(@"Absolute Path of image");
    ImageConverter _imageConverter = new ImageConverter();
    byte[] paramFileStream= (byte[])_imageConverter.ConvertTo(newImage, typeof(byte[]));

    var formContent = new MultipartFormDataContent
    {
        // Send form text values here
        {new StringContent("value1"),"key1"},
        {new StringContent("value2"),"key2" },
        // Send Image Here
        {new StreamContent(new MemoryStream(paramFileStream)),"imagekey","filename.jpg"}
    };

    var myHttpClient = new HttpClient();
    var response = await myHttpClient.PostAsync(actionUrl.ToString(), formContent);
    string stringContent = await response.Content.ReadAsStringAsync();

    return response;
}

这是一个对我有用的完整示例。boundary请求中的值由.NET自动添加。

var url = "http://localhost/api/v1/yourendpointhere";
var filePath = @"C:\path\to\image.jpg";

HttpClient httpClient = new HttpClient();
MultipartFormDataContent form = new MultipartFormDataContent();

FileStream fs = File.OpenRead(filePath);
var streamContent = new StreamContent(fs);

var imageContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");

form.Add(imageContent, "image", Path.GetFileName(filePath));
var response = httpClient.PostAsync(url, form).Result;

预加载器Dotnet 3.0 Core的示例

ProgressMessageHandler processMessageHander = new ProgressMessageHandler();

processMessageHander.HttpSendProgress += (s, e) =>
{
    if (e.ProgressPercentage > 0)
    {
        ProgressPercentage = e.ProgressPercentage;
        TotalBytes = e.TotalBytes;
        progressAction?.Invoke(progressFile);
    }
};

using (var client = HttpClientFactory.Create(processMessageHander))
{
    var uri = new Uri(transfer.BackEndUrl);
    client.DefaultRequestHeaders.Authorization =
    new AuthenticationHeaderValue("Bearer", AccessToken);

    using (MultipartFormDataContent multiForm = new MultipartFormDataContent())
    {
        multiForm.Add(new StringContent(FileId), "FileId");
        multiForm.Add(new StringContent(FileName), "FileName");
        string hash = "";

        using (MD5 md5Hash = MD5.Create())
        {
            var sb = new StringBuilder();
            foreach (var data in md5Hash.ComputeHash(File.ReadAllBytes(FullName)))
            {
                sb.Append(data.ToString("x2"));
            }
            hash = result.ToString();
        }
        multiForm.Add(new StringContent(hash), "Hash");

        using (FileStream fs = File.OpenRead(FullName))
        {
            multiForm.Add(new StreamContent(fs), "file", Path.GetFileName(FullName));
            var response = await client.PostAsync(uri, multiForm);
            progressFile.Message = response.ToString();

            if (response.IsSuccessStatusCode) {
                progressAction?.Invoke(progressFile);
            } else {
                progressErrorAction?.Invoke(progressFile);
            }
            response.EnsureSuccessStatusCode();
        }
    }
}

X509Certificate clientKey1 = null;
clientKey1 = new X509Certificate(AppSetting["certificatePath"],
AppSetting["pswd"]);
string url = "https://EndPointAddress";
FileStream fs = File.OpenRead(FilePath);
var streamContent = new StreamContent(fs);

var FileContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
FileContent.Headers.ContentType = MediaTypeHeaderValue.Parse("ContentType");
var handler = new WebRequestHandler();


handler.ClientCertificateOptions = ClientCertificateOption.Manual;
handler.ClientCertificates.Add(clientKey1);
handler.ServerCertificateValidationCallback = (httpRequestMessage, cert, cetChain, policyErrors) =>
{
    return true;
};


using (var client = new HttpClient(handler))
{
    // Post it
    HttpResponseMessage httpResponseMessage = client.PostAsync(url, FileContent).Result;

    if (!httpResponseMessage.IsSuccessStatusCode)
    {
        string ss = httpResponseMessage.StatusCode.ToString();
    }
}

我添加了一个代码段，该代码段显示了如何将文件发布到已通过DELETE http动词公开的API。上载带有DELETE http动词的文件并不常见，但可以使用。我已经假定Windows NTLM身份验证可以授权调用。

一个人可能面临的问题是HttpClient.DeleteAsync方法的所有重载都没有参数来HttpContent获取PostAsync方法

var requestUri = new Uri("http://UrlOfTheApi");
using (var streamToPost = new MemoryStream("C:\temp.txt"))
using (var fileStreamContent = new StreamContent(streamToPost))
using (var httpClientHandler = new HttpClientHandler() { UseDefaultCredentials = true })
using (var httpClient = new HttpClient(httpClientHandler, true))
using (var requestMessage = new HttpRequestMessage(HttpMethod.Delete, requestUri))
using (var formDataContent = new MultipartFormDataContent())
{
    formDataContent.Add(fileStreamContent, "myFile", "temp.txt");
    requestMessage.Content = formDataContent;
    var response = httpClient.SendAsync(requestMessage).GetAwaiter().GetResult();

    if (response.IsSuccessStatusCode)
    {
        // File upload was successfull
    }
    else
    {
        var erroResult = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
        throw new Exception("Error on the server : " + erroResult);
    }
}

您需要在C＃文件顶部的名称空间下方：

using System;
using System.Net;
using System.IO;
using System.Net.Http;

PS对不起，我的代码中使用了很多块（IDisposable模式）。不幸的是，使用C＃构造的语法不支持在单个语句中初始化多个变量。

public async Task<object> PassImageWithText(IFormFile files)
{
    byte[] data;
    string result = "";
    ByteArrayContent bytes;

    MultipartFormDataContent multiForm = new MultipartFormDataContent();

    try
    {
        using (var client = new HttpClient())
        {
            using (var br = new BinaryReader(files.OpenReadStream()))
            {
                data = br.ReadBytes((int)files.OpenReadStream().Length);
            }

            bytes = new ByteArrayContent(data);
            multiForm.Add(bytes, "files", files.FileName);
            multiForm.Add(new StringContent("value1"), "key1");
            multiForm.Add(new StringContent("value2"), "key2");

            var res = await client.PostAsync(_MEDIA_ADD_IMG_URL, multiForm);
        }
    }
    catch (Exception e)
    {
        throw new Exception(e.ToString());
    }

    return result;
}