c# - 使用 HttpClient 将文件上传到 ASP.NET WebApi 2

Question

我有这个 HttpClient 用于发布文件:

var content = new MultipartFormDataContent(Guid.NewGuid().ToString())
{
    new StringContent(JsonConvert.SerializeObject(parameters), Encoding.UTF8, "application/json")
};

foreach (var file in files)
{
    var byteContent = new ByteArrayContent(file.Data);

    content.Add(byteContent, file.FieldName, file.FileName);
}

return await _client.PostAsync(_apiUrl + apiRelativeUrl, content);

但是我的 ASP.NET WebApi Controller 给出错误 500，但出现以下异常:

System.IO.IOException: Unexpected end of MIME multipart stream. MIME multipart message is not complete.

WebApi Controller 代码是

if (Request.Content.IsMimeMultipartContent())
{
    var multipart = await Request.Content.ReadAsMultipartAsync(); //this line throws the exception
    var fileContent = multipart.Contents.FirstOrDefault();

    if (fileContent != null)
    {
        var photo = await fileContent.ReadAsByteArrayAsync();
    }
}

我做错了什么？

Answer 1

基本上我使用自定义流来附加 asp.net web api 期望的换行符。

Stream reqStream = Request.Content.ReadAsStreamAsync().Result;
MemoryStream tempStream = new MemoryStream();
reqStream.CopyTo(tempStream);



tempStream.Seek(0, SeekOrigin.End);
StreamWriter writer = new StreamWriter(tempStream);
writer.WriteLine();
writer.Flush();
tempStream.Position = 0;


 StreamContent streamContent = new StreamContent(tempStream);
 foreach(var header in Request.Content.Headers)
 {
     streamContent.Headers.Add(header.Key, header.Value);
 }

// Read the form data and return an async task.
 await streamContent.ReadAsMultipartAsync(provider);

并在web.config中添加如下代码

<system.web>
    <httpRuntime maxRequestLength="30000000" />
</system.web>

<system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="30000000" />
      </requestFiltering>
    </security>
</system.webServer>

希望这对您有所帮助。