Question

我正在使用Windows Phone 7.如何从以下代码中获取响应值???

private void sampleRequest()
{
    try
    {
        HttpWebRequest httpLoginRequest = (HttpWebRequest)WebRequest.Create(new Uri(DisplayMessage.Authentication_URL ));
        httpLoginRequest.Method = DisplayMessage.Get_Method;
        Parameters = new Dictionary<string, string>();
        httpLoginRequest.BeginGetResponse(new AsyncCallback(GetLoginCallback), httpLoginRequest);
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

private void GetLoginCallback(IAsyncResult asynchronousResult)
{
    try
    {
        HttpWebRequest httpRequest = (HttpWebRequest)asynchronousResult.AsyncState;
        HttpWebResponse httpresponse = (HttpWebResponse)httpRequest.EndGetResponse(asynchronousResult);
    }
    catch(WebException ex)
    {

    }
}

SampleRequest()放在不同的类中，例如说classA。现在我需要classB中的httpresponse值。任何人都帮助我实现这一目标。

提前致谢

Answer 1

有几种方法可以做到这一点：

- 第一种方法是使用Microsoft.Bcl.Async nuget软件包，这个软件包使您能够在Windows Phone 7应用程序中使用async / await，并使您能够“只获得返回值”等待sampleRequest，就像它不是异步的那样：

    private async Task<WebResponse> sampleRequest()
    {
        try
        {
            HttpWebRequest httpLoginRequest = (HttpWebRequest)WebRequest.Create(new Uri(DisplayMessage.Authentication_URL));
            httpLoginRequest.Method = DisplayMessage.Get_Method;
            Parameters = new Dictionary<string, string>();
            WebResponse webResponse =await httpLoginRequest.GetResponseAsync();
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

可以像这样在classB中使用：

   WebResponse response=await classAInstance.sampleRequest()

- 第二种方法是将您自己的回调作为sampleRequest的参数传递：

    public class State
    {
        public HttpWebRequest WebRequest { get; set; }
        public Action<HttpWebResponse > ResponseCallBack;
    }

    void sampleRequest(Action<HttpWebResponse > responseCallBack)
    {
        HttpWebRequest httpLoginRequest = (HttpWebRequest)WebRequest.Create(new Uri(DisplayMessage.Authentication_URL));
        //httpLoginRequest.Method = DisplayMessage.Get_Method;
        //Parameters = new Dictionary<string, string>();
        httpLoginRequest.BeginGetResponse(new AsyncCallback(GetLoginCallback), 
            new State(){WebRequest = httpLoginRequest,
                        ResponseCallBack = responseCallBack
            });
    }



    private void GetLoginCallback(IAsyncResult asynchronousResult)
    {
        try
        {
            State state= (State)asynchronousResult.AsyncState;
            HttpWebResponse httpresponse = (HttpWebResponse)state.WebRequest.EndGetResponse(asynchronousResult);
              ...

             //Dispatch request back to ui thread
              Deployment.Current.Dispatcher.BeginInvoke(() =>
              {
                   state.ResponseCallBack(httpresponse );
               });
        }
        catch(WebException ex)
        {

        }
    }

你可以在classB中使用的

：

classAInstance.sampleRequest((httpResponse)=>{
   //Do what you want with http response here
});

- 第三种方法是在你的classA上添加一个你将在tGetLoginCallback中触发并在classB中注册事件的事件：

   public event EventHandler<Response> LoginComplete;


   void sampleRequest(){
      //identical original one
      ....
    }


    private void GetLoginCallback(IAsyncResult asynchronousResult)
    {
        try
        {
            HttpWebRequest httpRequest = (HttpWebRequest)asynchronousResult.AsyncState;
            HttpWebResponse httpresponse = (HttpWebResponse)httpRequest.EndGetResponse(asynchronousResult);

            ...

              //Dispatch request back to ui thread
              Deployment.Current.Dispatcher.BeginInvoke(() =>
              {
                   if (LoginComplete != null)
                   {
                        LoginComplete(this,response);
                   }
               });

        }
        catch (WebException ex)
        {

        }
    }

如何从回调函数wp7获取响应值

1 个答案: