I have one new problem. I want to do some operations with the response, but I get a NullReferenceException, because it isn't arrived yet... Here is my code:
public partial class MainPage : PhoneApplicationPage
{
public static string res = null;
// Constructor
public MainPage()
{
InitializeComponent();
string Url = "http://twitter.com";
WebRequest req = WebRequest.Create(Url);
req.BeginGetResponse(new AsyncCallback(request_CallBack), req);
int i = MainPage.res.Length; // NullReferenceException
}
void request_CallBack(IAsyncResult result)
{
WebRequest webRequest = result.AsyncState as WebRequest;
WebResponse response = (WebResponse)webRequest.EndGetResponse(result);
Stream baseStream = response.GetResponseStream();
using (StreamReader reader = new StreamReader(baseStream))
{
res = reader.ReadToEnd();
Dispatcher.BeginInvoke(() => { MessageBox.Show("The response is arrived."); });
Dispatcher.BeginInvoke(() => { tbResponse.Text = res; });
}
}
}
But when I use the ManualResetEvent class, my app is just hanging, because of the if(dataReady.WaitOne()) line. Here is the complete code with the ManualResetEvent class:
public partial class MainPage : PhoneApplicationPage
{
public static string res = null;
ManualResetEvent dataReady;
// Constructor
public MainPage()
{
InitializeComponent();
string Url = "http://twitter.com";
dataReady = new ManualResetEvent(false);
WebRequest req = WebRequest.Create(Url);
req.BeginGetResponse(new AsyncCallback(request_CallBack), req);
if (dataReady.WaitOne())
{
int i = MainPage.res.Length;
}
}
void request_CallBack(IAsyncResult result)
{
WebRequest webRequest = result.AsyncState as WebRequest;
WebResponse response = (WebResponse)webRequest.EndGetResponse(result);
Stream baseStream = response.GetResponseStream();
using (StreamReader reader = new StreamReader(baseStream))
{
res = reader.ReadToEnd();
Dispatcher.BeginInvoke(() => { MessageBox.Show("The response is arrived."); });
Dispatcher.BeginInvoke(() => { tbResponse.Text = res; });
}
dataReady.Set();
}
}
So, there is my question: How can I wait the response and do operations with it? (I tried to use the Application.DoEvent method, but it isn't exist in WP7...)
Currenlty you are using one of the asynchronous methods of
WebRequest
. If you want to wait for a response, you can simply use the equivalent synchronous methodGetResponse
.http://msdn.microsoft.com/en-us/library/system.net.webrequest.getresponse.aspx