Question

晚安，我正在尝试使用HttpWebRequest.BeginGetResponse方法调用UI线程，在CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync方法内部更新propualty。但它不起作用，我不知道它是如何工作的。有我的代码：

private void DebutReponse(IAsyncResult resultatAsynchrone)
    {
        HttpWebRequest requete = (HttpWebRequest)resultatAsynchrone.AsyncState;
        Stream postStream = requete.EndGetRequestStream(resultatAsynchrone);

        string donneesAEnvoyer = "username=" + Name + "&password=" + Password + "&email=" + Email;

        string lol = donneesAEnvoyer;
        byte[] tableau = Encoding.UTF8.GetBytes(donneesAEnvoyer);
        postStream.Write(tableau, 0, donneesAEnvoyer.Length);
        postStream.Close();
        requete.BeginGetResponse(FinReponse, requete);
    }

    private void FinReponse(IAsyncResult resultatAsynchrone)
    {
        HttpWebResponse aResp = null;
        try
        {
            HttpWebRequest requete = (HttpWebRequest)resultatAsynchrone.AsyncState;
            WebResponse webResponse = requete.EndGetResponse(resultatAsynchrone);
            Stream stream = webResponse.GetResponseStream();

            StreamReader streamReader = new StreamReader(stream);
            string reponse = streamReader.ReadToEnd();
            stream.Close();
            streamReader.Close();
            webResponse.Close();

            //ErrorGridHeight = new GridLength(0.3, GridUnitType.Star);
            ErrorMsg = msgSucceed;
         }
        catch (WebException e)
        {
            if (e.Response != null)
            {
                aResp = e.Response as HttpWebResponse;
            }
        }
        if (aResp != null)
            await errorFunc();
    }

    private async Task errorFunc()
    {
        await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => ErrorMsg = msgFailed);
    }

我有一个错误告诉我，我只能在await方法中使用async运算符，并返回Task。我不知道它是如何运作的。

编辑：好的，所以我稍微改变了我的代码以避免这个功能的问题：

requete.BeginGetResponse(FinReponse, requete);

因为她想要一个具有特定原型的功能所以我这样做了：

private async Task lol(IAsyncResult resultatAsynchrone)
    {
        HttpWebResponse aResp = null;
        try
        {
            HttpWebRequest requete = (HttpWebRequest)resultatAsynchrone.AsyncState;
            WebResponse webResponse = requete.EndGetResponse(resultatAsynchrone);
            Stream stream = webResponse.GetResponseStream();

            StreamReader streamReader = new StreamReader(stream);
            string reponse = streamReader.ReadToEnd();
            stream.Close();
            streamReader.Close();
            webResponse.Close();

            //ErrorGridHeight = new GridLength(0.3, GridUnitType.Star);
            ErrorMsg = msgSucceed;
        }
        catch (WebException e)
        {
            if (e.Response != null)
            {
                aResp = e.Response as HttpWebResponse;
            }
        }
        if (aResp != null)
            await errorFunc();        
    }

    private void FinReponse(IAsyncResult resultatAsynchrone)
    {
        Task.Run(() => lol(resultatAsynchrone));
    }

    private async Task errorFunc()
    {
        await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => ErrorMsg = msgFailed);
    }

唯一的问题是它不会改变这个属性，它不会进入我的属性集。我有一个例外：

System.NotImplementedExeption

感谢您的帮助。

Answer 1

尝试将errorFunc()更改为此。

private void errorFunc()
{
    CoreApplication.MainView.CoreWindow.Dispatcher.BeginInvoke(() =>
    {
        ErrorMsg = msgFailed;
    });
}

我还找到了另一个地方，你试图改变ErrorMsg，并调用UI线程。这是代码ErrorMsg = msgSucceed;的行。我建议使用相同的方法，所以用这个代替行：

CoreApplication.MainView.CoreWindow.Dispatcher.BeginInvoke(() =>
{
    ErrorMsg = msgSucceed;
});

Answer 2

您必须FinReponse方法async才能使用await运算符：

private async void FinReponse(IAsyncResult resultatAsynchrone)

Answer 3

所以我找到了访问UI的答案，我必须使用：

            Deployment.Current.Dispatcher.BeginInvoke(()=>mym());

它完美无缺。谢谢你的一切。

在HttpWebRequest.BeginGetResponse中调用UI线程

3 个答案: