C# 从异步HttpWebRequest流读取NullReferenceException

我正在为WindowsPhone7编写一个应用程序。该应用程序首先通过HttpWebRequest发送数据，然后从服务器接收数据。大多数情况下，它工作正常，但有时，在正确接收部分数据后，我在Stream.Read（）函数中得到一个NullReferenceException

当用户按下按钮时，通信开始。然后创建HttpWebRequest：

HttpWebRequest request = (HttpWebRequest) WebRequest.Create(sUri);
request.Method = "POST";
request.BeginGetRequestStream(GetRequestStreamCallback, request);

请求回调方法：

private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{                      
  HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
  postStream = request.EndGetRequestStream(asynchronousResult);

  this.bSyncOK = Send(); //This is my method to send data to the server
  postStream.Close();

  if (this.bSyncOK)
    request.BeginGetResponse(GetResponseCallback, request);
  else
    manualEventWait.Set(); //This ManualResetEvent notify a thread the end of the communication, then a progressbar must be hidden
}

private void GetResponseCallback(IAsyncResult asynchronousResult)
{
  HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
  using (HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult) )
  {
    using (streamResponse = new StreamReader(response.GetResponseStream() ) )
    {
      this.bSyncOK = Recv(); //This is my generic method to receive the data
      streamResponse.Close();
    }
    response.Close();
  }
  manualEventWait.Set(); //This ManualResetEvent notify a thread the end of the communication, then a progressbar must be hidden
}

响应回调方法：

private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
{                      
  HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
  postStream = request.EndGetRequestStream(asynchronousResult);

  this.bSyncOK = Send(); //This is my method to send data to the server
  postStream.Close();

  if (this.bSyncOK)
    request.BeginGetResponse(GetResponseCallback, request);
  else
    manualEventWait.Set(); //This ManualResetEvent notify a thread the end of the communication, then a progressbar must be hidden
}

private void GetResponseCallback(IAsyncResult asynchronousResult)
{
  HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
  using (HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asynchronousResult) )
  {
    using (streamResponse = new StreamReader(response.GetResponseStream() ) )
    {
      this.bSyncOK = Recv(); //This is my generic method to receive the data
      streamResponse.Close();
    }
    response.Close();
  }
  manualEventWait.Set(); //This ManualResetEvent notify a thread the end of the communication, then a progressbar must be hidden
}

最后，这是读取流数据时出现异常的代码：

int iBytesLeidos;
byte[] byteArrayUTF8 = new byte[8];

iBytesLeidos = streamResponse.BaseStream.Read(byteArrayUTF8, 0, 8); //NullReferenceException!!! -Server always send 8 bytes here-

当应用程序启动时，我创建一个后台线程，该线程经常向服务器发送信息。后台通信和手动通信可以同时运行。这可能是个问题吗

---

谢谢。

您的

流响应在后一段代码中声明在哪里？它是否与3d代码段中的对象相同？可能您只是使用了另一个变量，而不是实际的流。
如果
streamResponse
是全局变量，则在从另一个线程访问时可能会导致问题。将
流
作为参数传递给
Recv

using (StreamReader streamResponse = new StreamReader(response.GetResponseStream() ) )
{
  this.bSyncOK = Recv(streamResponse); //This is my generic method to receive the data
  streamResponse.Close();
}

在第二个代码段中，尝试删除“postStream.Close（）；”
 是的，所有代码都属于同一类。这是“streamResponse”->“private static StreamReader streamResponse”的声明；您可以检查
streamResponse
或
.BaseStream
是否为空吗？好的，我在桌面上尝试了您的代码——它可以工作。你能检查一下我的版本并确认你的版本看起来是一样的吗？还有可能是比赛条件——我没有注意到你在哪里重置了你的赛事。我已将并行版本添加到我的解决方案中。