僅在第一個HTTP請求中獲得空響應Windows Phone 8

Question

每當我在Windows Phone 8中啟動應用程序並發送http GET請求時，我都會得到空響應。 這只是第一個請求，其他請求對相同url的響應也不為空。

這是代碼：

string res = "";

private void ReadUrlAsync(string url)
    {
        var request = HttpWebRequest.Create(new Uri(url)) as HttpWebRequest;
       // request.Accept = "application/json;odata=verbose";
        request.BeginGetResponse(ResponseCallback, request);
    }

    private void ResponseCallback(IAsyncResult asyncResult)
    {
        HttpWebRequest request = (HttpWebRequest)asyncResult.AsyncState;
        HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(asyncResult);
        string data;
        using (Stream responseStream = response.GetResponseStream())
        {

            using (var reader = new System.IO.StreamReader(responseStream))
            {
                data = reader.ReadToEnd();
            }
        }
        res = data;
    }

Answer 1

我使用了一些不同的代碼並找到了解決方案：

        HttpClient cl = new HttpClient();
       return await cl.GetStringAsync(new Uri(url));