问Windows Phone 7: web服务问题

EN

    public partial class MainPage : PhoneApplicationPage
{
    // Constructor
    public MainPage()
    {
        InitializeComponent();
    }

    /// <summary>
    /// Event handler to handle when this page is navigated to
    /// </summary>
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        SearchService searchService = new SearchService();
        searchService.GetCategoryCounter("pizza")
        Globals.pizzaCounter = searchService.Counter;    

        searchService.GetCategoryCounter("pasta")
        Globals.pastaCounter = searchService.Counter;

        pizzacounter.Text = Globals.pizzaCounter;
        pastacounter.Text = Globals.pastaCounter;
    }
}

public class SearchService
{

    #region member variables
    private string currentCategoryCount = "";
    public event PropertyChangedEventHandler PropertyChanged;

    #endregion member variables

    #region accessors
    public String Counter
    {
        get
        {
            return currentCategoryCount;
        }
        set
        {
            if (value != currentCategoryCount)
            {
                currentCategoryCount = value;
                NotifyPropertyChanged("Counter");
            }
        }
    }
    #endregion accessors

    #region private Helpers

    /// <summary>
    /// Raise the PropertyChanged event and pass along the property that changed
    /// </summary>
    private void NotifyPropertyChanged(string property)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(property));
        }
    }

    #endregion private Helpers


    /*
    * GetCategoryCounter Method:
    * 
    * @param category
    *            : the category whose counter is to be retrieved
    */
    public void GetCategoryCounter(string category)
    {
        try
        {
            // form the URI
            UriBuilder fullUri = new UriBuilder("http://www.mywebsite.com/items/stats");
            fullUri.Query = "category=" + category;

            // initialize a new WebRequest
            HttpWebRequest counterRequest = (HttpWebRequest)WebRequest.Create(fullUri.Uri);

            // set up the state object for the async request
            CounterUpdateState counterState = new CounterUpdateState();
            counterState.AsyncRequest = counterRequest;

            // start the asynchronous request
            counterRequest.BeginGetResponse(new AsyncCallback(HandleCounterResponse), counterState);
            return;
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

    /// <summary>
    /// Handle the information returned from the async request
    /// </summary>
    /// <param name="asyncResult"></param>
    private void HandleCounterResponse(IAsyncResult asyncResult)
    {
        // get the state information
        CounterUpdateState counterState = (CounterUpdateState)asyncResult.AsyncState;
        HttpWebRequest counterRequest = (HttpWebRequest)counterState.AsyncRequest;

        // end the async request
        counterState.AsyncResponse = (HttpWebResponse)counterRequest.EndGetResponse(asyncResult);

        Stream streamResult;
        string currentCount = "";

        try
        {
            // get the stream containing the response from the async call
            streamResult = counterState.AsyncResponse.GetResponseStream();

            StreamReader reader = new StreamReader(streamResult);
            currentCount = reader.ReadToEnd();

            // copy the data over
            Deployment.Current.Dispatcher.BeginInvoke(() =>
            {
                Counter = currentCount;
            });
        }
        catch (FormatException ex)
        {
            throw ex;
        }

    }
}

/// <summary>
/// State information for our BeginGetResponse async call
/// </summary>
public class CounterUpdateState
{
    public HttpWebRequest AsyncRequest { get; set; }
    public HttpWebResponse AsyncResponse { get; set; }
}