确保从Windows Phone上传文件到ASP.NET MVC 3

Question

确保从Windows Phone上传文件到ASP.NET MVC 3

3

我正在开发一个 Windows Phone 应用程序。这个应用程序将允许用户拍照并上传到我的服务器。我已经成功实现了这个功能。然而，我注意到有时候图片上传不完整。我怀疑这是因为有人在上传完成之前让应用程序休眠了，或者连接中断了。我真的不知道如何解决这个问题。我在这里放置了我的代码。希望有人能提供一些见解。

Client Side - Windows Phone App - Picture.cs
--------------------------------------------
public event EventHandler Upload_Succeeded;
public event EventHandler Upload_Failed;
public void Upload()
{
  try {
    WebRequest request = HttpWebRequest.Create(GetBackendPictureUploadUrl());
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";
    request.BeginGetRequestStream(new AsyncCallback(UploadBeginGetRequestStreamCallBack), request);
  } catch (Exception ex)
  {
    Upload_Failed(this, EventArgs.Empty);
  }
}

private void UploadBeginGetRequestStreamCallBack(IAsyncResult ar)
{
  try {
    StringBuilder sb = new StringBuilder();
    this.ImageBytes.ToList<byte>().ForEach(x => sb.AppendFormat("{0}.", Convert.ToUInt32(x)));

    Dictionary<string, string> parameters = new Dictionary<string, string>();
    parameters.Add("username", GetUsername());
    parameters.Add("pictureByts", sb.ToString());

    string data = string.Empty;
    foreach (string key in parameters.Keys)
    {
      data += key;
      data += "=";
      data += parameters[key];
      data += "&";
    }
    data = data.Substring(0, data.Length - 1);

    HttpWebRequest webRequest = (HttpWebRequest)(ar.AsyncState);
    using (Stream postStream = webRequest.EndGetRequestStream(ar))
    {
      byte[] byteArray = Encoding.UTF8.GetBytes(data);
      postStream.Write(byteArray, 0, byteArray.Length);
      postStream.Close();
    }
    webRequest.BeginGetResponse(new AsyncCallback(Upload_Completed), webRequest);
  } catch (Exception ex)
  {
    Upload_Failed(this, EventArgs.Empty);
  }
}

private void Upload_Completed(IAsyncResult result)
{
  Upload_Succeeded(this, EventArgs.Empty);
}

Server Size - ASP.NET MVC - MyController.cs
-------------------------------------------
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult AddPicture(string username, string pictureBytes)
{
  string path = ConfigurationManager.AppSettings["pictureDirectory"] + "/" + username + "/";
  if (Directory.Exists(path) == false)
    Directory.CreateDirectory(path);
  string filePath = path + "/" + Guid.NewGuid().ToString() + ".png";

  // Save the picture to the file system
  string[] bytesToConvert = pictureBytes.Split('.');
  List<byte> fileBytes = new List<byte>();
  bytesToConvert.ToList<string>().Where(x => !string.IsNullOrEmpty(x)).ToList<string>().ForEach(x => fileBytes.Add(Convert.ToByte(x)));

  using (FileStream fileStream = new FileStream(filePath, FileMode.Create))
  {
    byte[] bytes = fileBytes.ToArray();
    fileStream.Write(bytes, 0, bytes.Length);
    fileStream.Close();
  }
}

我很困惑，这段代码在我看来是正确的。但我注意到服务器上正在写入文件。有时它们只是灰色图像。有时看起来只写了图像的一部分而不是全部。我做错了什么？如何确保文件完全上传/写入？肯定有某种方法可以解决这个问题，Facebook等显然已经做到了。我做错了什么？

- user609886

你有服务器端的代码吗？ - Les

抱歉，我看到了。您能否发布捕获字符串pictureBytes并调用AddPicture()的代码？ - Les

1个回答

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- Les · Answer 1

你需要在上传方法中设置ContentLength。为此，你应该在进行异步请求之前计算完成的数据缓冲区。然后你将拥有所需的长度（在UTF8编码后）。当回调发生时，将数据提供给流。