等待HttpWebRequest.BeginGetResponse在Windows Phone 7的完成 [英] Wait for HttpWebRequest.BeginGetResponse to finish in Windows Phone 7

问题描述

我想使用在Silverlight的异步的HttpWebRequest Windows Phone的。直到我到了那里我应该叫

I'm trying to use the async HttpWebRequest in Silverlight for Windows Phone. All works perfect until I get to the where I should call

private static ManualResetEvent allDone = new ManualResetEvent(false);
...
request.BeginGetResponse(new AsyncCallback(GetResponseCallback), request);
allDone.WaitOne();
Debug.WriteLine("All done!");

在 GetResponseCallback ：

private void GetResponseCallback(IAsyncResult asynchronousResult)
{
    try
    {
        request = (HttpWebRequest)asynchronousResult.AsyncState;
        response = (HttpWebResponse)request.EndGetResponse(asynchronousResult);
        allDone.Set();
    }
    catch (Exception e)
    {
        Debug.WriteLine("Got Exception in GetResponseCallback: " + e.Message);
    }
}

调用后 allDone .WaitOne（）; 它只是挂起...

为什么

推荐答案

这只是需要多一点的转变在从阻塞/等待在WP7平台上的异步角度思考思考了。其结果是，用户总是能够与UI交互。

This just takes a bit of a shift in thinking away from blocking/waiting to thinking in async terms on the WP7 platform. The result is the user is always able to interact with the UI.

移动呼叫到您的完成码（在这种情况下的WriteLine）插入CompletedEventHandler和任何UI更新马歇尔回到UI线程以

Move a call to your completion code (writeline in this case) into your CompletedEventHandler and for any UI updates marshall back to the UI thread with

Dispatcher.BeginInvoke( () => { /* your UI update code */ } )

如果有一些不应该，而你的异步操作执行时那么这些与可交互的UI元素控件可以隐藏或禁用的临时

If there are any UI elements that should not be interacted with while your async op is executing then these controls can be hidden or disabled for the interim.

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