c# - HttpWebRequest.BeginGetResponse

Question

我需要对 Web 资源发出异步请求并使用此页面 (link to full example) 中的示例:

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，此代码的最后一行执行卡住(2-3 秒)(我可以使用调试器观看它)。

为什么？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;
}

因为文本框值的跨线程，但这是 wpf 应用程序，我会重新标记它，顺便说一句，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
        }
    }