c# - HttpWebRequest Response Stream 只返回 64k 的数据

Question

我们正在使用 Web API 为我们的应用程序提供 RESTful 服务，该应用程序目前正在使用 WPF，因此需要服务客户端。

我们遇到的问题是，当响应大小超过 64k 时，底层流会在 64k 处停止并在请求更多数据时抛出异常，尽管 ContentLength 更大(在测试用例中为 ~125k)

这是我们调用服务的方法:

private HttpWebResponse CallServiceMethod<TDto>(Uri serviceURL, string method, out WebException requestExceptionDetail, TDto dto = null) where TDto : DTOBase
{
  HttpWebRequest request;
  HttpWebResponse response;
  Encoding enc;
  string encodedDto;
  byte[] encodedDtoArray;
  Stream writeStream;

  request = WebRequest.CreateHttp(serviceURL);
  request.Method = method;

  if (dto != null)
  {
    enc = UTF8Encoding.Default;
    encodedDto = String.Concat("=", JsonConvert.SerializeObject(dto));
    encodedDtoArray = enc.GetBytes(encodedDto);

    request.ContentLength = encodedDtoArray.Length;
    request.ContentType = "application/x-www-form-urlencoded";

    writeStream = request.GetRequestStream();
    writeStream.Write(encodedDtoArray, 0, encodedDtoArray.Length);
    writeStream.Close();
  }

  requestExceptionDetail = null;

  try
  {
    response = (HttpWebResponse)request.GetResponse();
  }
  catch (WebException wex)
  {
    response = (HttpWebResponse)wex.Response;
    requestExceptionDetail = wex;
  }

  return response;
}

...这里有一个解码响应的方法，中间有一些胶合逻辑来传递响应。

private TObjectType DecodeResponse<TObjectType>(HttpWebResponse webResponse)
{
  Encoding enc;
  StreamReader responseReader;
  string responseText;
  TObjectType retVal;

  // Obtain a string from the underlying response string
  enc = UTF8Encoding.Default;
  responseReader = new StreamReader(webResponse.GetResponseStream(), enc);
  responseText = responseReader.ReadToEnd();

  // Use JSon to deserialise the string
  retVal = JsonConvert.DeserializeObject<TObjectType>(responseText);

  return retVal;
}

这种事情我们也试过，但是没用:

private TObjectType DecodeResponse<TObjectType>(HttpWebResponse webResponse)
{
  Encoding enc;
  StreamReader responseReader;
  string responseText;
  TObjectType retVal;
  char[] buffer;
  int bufferSize, startPos, totalLength, readLength;
  StringBuilder sbx;

  // Obtain a string from the underlying response string
  enc = UTF8Encoding.Default;
  responseReader = new StreamReader(webResponse.GetResponseStream(), enc);

  totalLength = (int)webResponse.ContentLength;
  bufferSize = 65536;
  startPos = 0;
  buffer = new char[bufferSize];

  sbx = new StringBuilder(totalLength);
  //webResponse.GetResponseStream().

  while (startPos < totalLength)
  {
    readLength = Math.Min(bufferSize, totalLength - startPos);
    responseReader.Read(buffer, startPos, readLength);
    sbx.Append(buffer, 0, readLength);

    startPos += readLength;
  }

  //responseText = responseReader.ReadToEnd();
  responseText = sbx.ToString();

  // Use JSon to deserialise the string
  retVal = JsonConvert.DeserializeObject<TObjectType>(responseText);

  return retVal;
}

任何帮助将不胜感激;-)

Answer 1

进一步调查显示 HttpWebRequest 有一个名为 DefaultMaximumErrorResponseLength 的静态属性，默认设置为 65536。

它会合谋认为 .NET 框架包含这个恶魔般的属性，只要您的响应是文本/纯文本，它就可以工作，但如果它需要任何闭包 - 例如 XML 或 JSON - 它就会中断。

如需更多信息，请引用:

• http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.defaultmaximumerrorresponselength.aspx