如何使用Windows Phone 8进行HttpClient POST？它只是挂起 [英] How can I do HttpClient POST with Windows Phone 8 ? It just hangs

问题描述

我获得了Winodws Phone 8的webapi.client的alpha版本，下面的代码在请求后挂起..我做错了什么？

I got the alpha of webapi.client for Winodws Phone 8 and the code below hangs after the request.. am I doing something wrong ?

var client = new HttpClient();
        client.BaseAddress = new Uri("http://punkoutersoftware.azurewebsites.net");

        client.DefaultRequestHeaders.Accept.Add(
            new MediaTypeWithQualityHeaderValue("application/json"));

        var score = new DrunkMeterScore() { Name = "Joe", Score = 2.67 };






        //MediaTypeFormatter jsonFormatter = new JsonMediaTypeFormatter();
        //HttpContent content = new ObjectContent<DrunkMeterScore>(score, jsonFormatter);
        //var resp = client.PostAsync("api/DrunkMeterScore", content).Result;






        //Uri scoreUri = null;
        //HttpResponseMessage response = client.PostAsJsonAsync("api/DrunkMeterScore", score).Result;
        //if (response.IsSuccessStatusCode)
        //{
        //    scoreUri = response.Headers.Location;
        //}
        //else
        //{
        //    Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
        //}

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If you do SharePoint dev and have MSN add me!! [e-mail] We can help each other out. My SharePoint Blog ---> http://punkouter.spaces.live.com/

推荐答案

目前尚不清楚您提供的代码如何被调用 借用其他一些代码，我可能会沿着以下几点做一些事情：

It is not clear from what you provided how this code is getting called.  Borrowing from some other code, I would probably do something along these lines:

public sealed class Class1 : IDisposable
{
    static readonly Tuple<bool, Uri> NoAnswer = new Tuple<bool, Uri>(false, null);

    readonly HttpClient _client = new HttpClient
                                    {
                                        BaseAddress = new Uri("http://punkoutersoftware.azurewebsites.net")
                                    };

    public Class1()
    {
        _client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    }

    #region IDisposable Members

    public void Dispose()
    {
        if (null != _client)
            _client.Dispose();
    }

    #endregion

    public async Task DoStuff(CancellationToken cancellationToken)
    {
        var score = new DrunkMeterScore
                    {
                        Name = "Joe",
                        Score = 2.67
                    };

        var scoreUri = await Retries.Retry((lastTry, ct) => PostScore(score, ct, lastTry), cancellationToken).ConfigureAwait(false);

        Debug.WriteLine("Got " + scoreUri);
    }

    async Task<Tuple<bool, Uri>> PostScore(DrunkMeterScore score, CancellationToken cancellationToken, bool isLastTry)
    {
        using (var response = await _client.PostAsJsonAsync("api/DrunkMeterScore", score, cancellationToken).ConfigureAwait(false))
        {
            if (response.IsSuccessStatusCode)
                return Tuple.Create(true, response.Headers.Location);

            // Don't retry 404s.
            if (isLastTry || response.StatusCode == HttpStatusCode.NotFound)
                response.EnsureSuccessStatusCode();
        }

        return NoAnswer;
    }
}

其中Retries如下所示：

Where Retries looks like this:

static class Retries
{
    public static async Task<T> Retry<T>(Func<bool, CancellationToken, Task<Tuple<bool, T>>> callback, CancellationToken cancellationToken)
    {
        var delay = 1000;

        for (var retry = 2; retry >= 0; --retry)
        {
            var isLastTry = 1 == retry;

            try
            {
                var result = await callback(isLastTry, cancellationToken);

                if (result.Item1)
                    return result.Item2;
            }
            catch (TaskCanceledException)
            {
                if (isLastTry || cancellationToken.IsCancellationRequested)
                    throw;

                // Some network timeout has happened; ignore it and try again.
            }
            catch (AggregateException aggregateException)
            {
                if (isLastTry || cancellationToken.IsCancellationRequested)
                    throw;

                aggregateException.Handle(ex => ex is TaskCanceledException);
            }

            await Task.Delay(delay, cancellationToken).ConfigureAwait(false);

            delay *= 2;
        }

        throw new TimeoutException("...something constructive...");
    }
}

然后使用类似的东西：

public partial class MainPage : PhoneApplicationPage
{
    readonly CancellationTokenSource _cancellationTokenSource = new CancellationTokenSource();
    readonly Class1 _class1;

    // Constructor
    public MainPage()
    {
        InitializeComponent();

        _class1 = new Class1();

        // Sample code to localize the ApplicationBar
        //BuildLocalizedApplicationBar();
    }

    async void Button1_Click(object sender, RoutedEventArgs e)
    {
        Button1.IsEnabled = false;

        try
        {
            await _class1.DoStuff(_cancellationTokenSource.Token);
        }
        finally
        {
            Button1.IsEnabled = true;
        }
    }
}

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