無法更新Web服務請求後的Windows Phone UI

Question

我可以成功地發出請求並從Windows服務中獲得響應，但我無法使用響應中得到的結果更新UI，它顯示無效的交叉線程異常。

這裏是我的代碼：

public void UpdateUI() 
{ 
    check = dat.Count; 
    for (int ci = 0; ci < check; ci++) 
    { 
     Datum dt = new Datum(); 
     dt = dat[ci]; 
     Title1 = dt.title; 
     Price = dt.price; 
     Id = dt.id; 
     Logo = dt.logo; 
     Featured = dt.featured; 

     System.Diagnostics.Debug.WriteLine("UpdateUI"); 
     System.Diagnostics.Debug.WriteLine(Title1.ToString()); 
     System.Diagnostics.Debug.WriteLine(Price.ToString()); 
     System.Diagnostics.Debug.WriteLine(Id.ToString()); 
     System.Diagnostics.Debug.WriteLine(Logo.ToString()); 
     System.Diagnostics.Debug.WriteLine(Featured.ToString()); 


     Grid grd = new Grid(); 
     grd.Name = "grd" + ci; 
     System.Diagnostics.Debug.WriteLine(grd.Name); 
     grd.Margin = new Thickness(5, 5, 5, 5); 
     grd.Background = new SolidColorBrush(Colors.LightGray); 

     Image img = new Image(); 
     img.Width = 150; 
     img.Height = 120; 
     img.HorizontalAlignment = System.Windows.HorizontalAlignment.Left; 

     Uri uri = new Uri("http://www.searchi.in/classifieds/dashboard/classifieds_images/big/"+Logo, UriKind.Absolute); 

     ImageSource imgSource = new BitmapImage(uri); 
     img.Source = imgSource; 

     TextBlock tb = new TextBlock(); 
     tb.MaxWidth=125; 
     tb.Height = 100; 
     tb.Text = Title1; 
     tb.Foreground = new SolidColorBrush(Colors.Black); 
     tb.FontSize = 22; 
     tb.VerticalAlignment = VerticalAlignment.Top; 
     tb.HorizontalAlignment = HorizontalAlignment.Stretch; 
     tb.TextAlignment = TextAlignment.Left; 



     TextBlock tb1 = new TextBlock(); 
     tb1.Width = 300; 
     tb1.Height = 100; 
     tb1.Text = " ₹ "+Price; 

     tb1.VerticalAlignment = VerticalAlignment.Bottom; 
     tb1.Foreground = new SolidColorBrush(Colors.Black); 
     tb1.FontSize = 22; 

     tb1.TextAlignment = TextAlignment.Center; 

     grd.Children.Add(img); 
     grd.Children.Add(tb); 
     grd.Children.Add(tb1); 
     grid.Children.Add(grd); 

    } 

} 

和代碼的請求：

void web() 
{ 
    // Create the web request object 
    var url = "http://searchi.in/appservice/classifides.php"; 
    HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url); 
    webRequest.Method = "POST"; 
    webRequest.ContentType = "application/x-www-form-urlencoded"; 
    // Start the request 

    webRequest.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), webRequest); 
    //asynchronousResult.AsyncWaitHandle.WaitOne(); 
    // webRequest.BeginGetResponse(new AsyncCallback(GetResponseCallback), webRequest); 

} 

void GetRequestStreamCallback(IAsyncResult asynchronousResult) 
{ 
    HttpWebRequest webRequest = (HttpWebRequest)asynchronousResult.AsyncState; 
    Stream postStream = webRequest.EndGetRequestStream(asynchronousResult); 

    System.Diagnostics.Debug.WriteLine("test"); 
    postStream.Close(); 
    // datacheck = 1; 
    cheker = true; 
    webRequest.BeginGetResponse(new AsyncCallback(GetResponseCallback), webRequest); 

    // asynchronous = asynchronousResult; 
    //asynchronousResult.AsyncWaitHandle.WaitOne(); 

    System.Diagnostics.Debug.WriteLine("2"); 
} 

void GetResponseCallback(IAsyncResult asynchronousResult) 
{ 
    try 
    { 
     HttpWebRequest webRequest = (HttpWebRequest)asynchronousResult.AsyncState; 
     System.Diagnostics.Debug.WriteLine("3"); 
     HttpWebResponse response = (HttpWebResponse)webRequest.EndGetResponse(asynchronousResult); 
     Stream receiveStream = response.GetResponseStream(); 
     StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8); 
     Response = readStream.ReadToEnd().ToString(); 

     System.Diagnostics.Debug.WriteLine("GetResponseCallback"); 
     System.Diagnostics.Debug.WriteLine(Response); 
     DataContractJsonSerializer serializer2 = new DataContractJsonSerializer(typeof(RootObject)); 
     RootObject ro = (RootObject)serializer2.ReadObject(receiveStream); 

     Success = ro.success; 
     Sort = ro.sort; 
     dat = ro.data; 

     readStream.Close(); 
     response.Close(); 

     //cheker = true; 
    } 
    catch (WebException e) 
    { 
     System.Diagnostics.Debug.WriteLine(e.ToString()); 
    } 

    UpdateUI(); 
} 

Answer 1

嘗試包調用UpdateUI()功能與Dispatcher.BeginInvoke。這將調用UI線程的功能以防止無效的跨線程異常：

...... 
Dispatcher.BeginInvoke(() => 
    { 
     UpdateUI(); 
    }); 
......