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我正在尝试使用 WebAPI 将图像从我的 windows phone 8 应用程序上传到 SQL 服务器数据库。我正在为图像使用模型类，它只包含属于图像所针对的项目的 ID、图像的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，它会引发如下所示的异常。有谁知道为什么会出错？此外，我对将图像存储到我的 SQL 数据库的其他方法持开放态度。感谢您的关注！

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;
            }
        }

例外

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)
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1 回答 1

1

我相信您的 HTTP 方法不正确。

代替 ...

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

尝试 ...

webClient.UploadStringAsync(uri, "POST", jsonData);
于 2013-08-14T19:59:31.653 回答