HttpWebRequest.BeginGetResponse

Question

我需要向Web资源发出异步请求并使用此页面中的示例(链接到完整示例):

HttpWebRequest myHttpWebRequest= (HttpWebRequest)WebRequest.Create("http://www.contoso.com");
RequestState myRequestState = new RequestState();  
myRequestState.request = myHttpWebRequest;
// Start the asynchronous request.
IAsyncResult result=
        (IAsyncResult) myHttpWebRequest.BeginGetResponse(new AsyncCallback(RespCallback),myRequestState);

但是当我测试应用程序时,执行冻结(在2-3秒内)在此代码的最后一行(我可以使用调试器观察它).

为什么？这是我的错误还是函数的标准行为？

Answer 1

你可以试试,我相信那更好

private void StartWebRequest(string url)
{
   HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
   request.BeginGetResponse(new AsyncCallback(FinishWebRequest), request);
}

private void FinishWebRequest(IAsyncResult result)
{
   HttpWebResponse response = (result.AsyncState as HttpWebRequest).EndGetResponse(result) as HttpWebResponse;
}

因为textbox'值的chross线程,但是这是wpf应用程序我会重拍这个,顺便说一下你可以使用webclient之类的

 private void tbWord_TextChanged(object sender, TextChangedEventArgs e)
    {
        WebClient wc = new WebClient();
        wc.DownloadStringCompleted += HttpsCompleted;
        wc.DownloadStringAsync(new Uri("http://en.wikipedia.org/w/api.php?action=opensearch&search=" + tbWord.Text)); 
    }
    private void HttpsCompleted(object sender, DownloadStringCompletedEventArgs e)
    {
        if (e.Error == null)
        {

             //do what ever 
             //with using e.Result
        }
    }