Question

我正在尝试使用WebAPI将我的Windows Phone 8应用程序中的图像上传到SQL Server数据库。我正在使用图像的模型类，它只包含属于图像所用项目的ID，图像名称和用于保存图像本身的字节数组。我使用WebClient对象来访问WebAPI方法。当我尝试上传图像时，它会抛出异常，如下所示。有谁知道它为什么会出错？另外，我对其他将图像存储到SQL数据库的方法持开放态度。谢谢你看看！

代码

private MemoryStream photoStream;

...

private void upload()
        {
            try
            {
                Images image = new Images();
                image.ImagesBytes = photoStream.ToArray();
                image.ImagesID = 3;
                image.ImagesCaption = "this is a test";

                string jsonData = JsonConvert.SerializeObject(image);

                WebClient webClient = new WebClient();
                webClient.Headers["Content-type"] = "application/json";
                webClient.Encoding = Encoding.UTF8;

                Uri uri = new Uri("http://myIP/api/Images/", UriKind.Absolute);
                webClient.UploadStringCompleted += new UploadStringCompletedEventHandler(webClient_UploadStringCompleted);
                webClient.UploadStringAsync(uri, "GET", jsonData);
            }
            catch
            {
                // Display the Uploaded message
                tbError.Visibility = Visibility.Visible;
            }
        }

...

        void webClient_UploadStringCompleted(object sender, UploadStringCompletedEventArgs e)
        {
            try
            {
                Images image = JsonConvert.DeserializeObject<Images>(e.Result);
            }
            catch (Exception ex)
            {
                // Display the Uploaded message
                tbError.Visibility = Visibility.Visible;
            }
        }

异常

System.Net.ProtocolViolationException: Operation is not valid due to the current state of the object.
   at System.Net.Browser.ClientHttpWebRequest.InternalBeginGetRequestStream(AsyncCallback callback, Object state)
   at System.Net.Browser.ClientHttpWebRequest.BeginGetRequestStream(AsyncCallback callback, Object state)
   at System.Net.WebClient.UploadBits(WebRequest request, Stream readStream, Byte[] buffer, Byte[] header, Byte[] footer, CompletionDelegate completionDelegate, AsyncOperation asyncOp)
   at System.Net.WebClient.UploadDownloadBits(WebRequest request, Stream readStream, Stream writeStream, Byte[] buffer, Byte[] header, Byte[] footer, CompletionDelegate upCompletionDelegate, CompletionDelegate downCompletionDelegate, AsyncOperation asyncOp)
   at System.Net.WebClient.UploadStringAsync(Uri address, String method, String data, Object userToken)

Answer 1

我认为您的HTTP方法不正确。

而不是......

webClient.UploadStringAsync(uri, "GET", jsonData);

试试......

webClient.UploadStringAsync(uri, "POST", jsonData);

使用ASP.NET WebAPI使用模型上载图像

1 个答案: