Question

我正在尝试从API中获取数据。

当我用如下所示的方法编写所有代码时，它可以正常工作。

private async void btvalidate_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            HttpClient client = new HttpClient();
            client.BaseAddress = new Uri("mybaseaddress");
            HttpResponseMessage response = await client.GetAsync("mylocaluri");
            if (response.IsSuccessStatusCode)// check whether response status is true
            {
                var data = response.Content.ReadAsStringAsync();//read the data in the response
                var msg = JsonConvert.DeserializeObject<myclassname>(data.Result.ToString());//convert the string response in json format
                validate.DataContext = msg;// assign the data received to stackpanel  
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Somethimng went wrong" + ex);
        }
    }

但是当我尝试在单独的类的方法中编写此代码并从click事件中调用它时，如下所示，它会在事件点击时挂起并且具有数据状态为WaitingforActivation ...

public class API
{
    public async Task<string> getAPI(string uri)
    {
        string data1 = null;
        var data=data1;

            using (HttpClient client = new HttpClient())
            {
                client.BaseAddress = new Uri("mybaseaddress");
                HttpResponseMessage response = await client.GetAsync(uri);
                if (response.IsSuccessStatusCode)// check whether response status is true
                {
                    data = response.Content.ReadAsStringAsync().Result;//read the data in the response
                }
           }
        return data;
    } 
}

private void btcount_Click(object sender, RoutedEventArgs e)
    {
        var data = api.getAPI("mylocaluri");
        var msg = JsonConvert.DeserializeObject<myclassname>(data.Result.ToString());//convert the string response in json format
        validate.DataContext = msg;// assign the data received to stackpanel
    }

有人能告诉我我做错了吗？

提前感谢您的帮助。

Answer 1

你causing a deadlock by calling Result，我在博客上完整解释。

最好的解决方案是use async "all the way"，正如我在MSDN上关于%最佳做法的文章中所述。

在这种特殊情况下，请将async替换为Result：

await

在旁注中，请考虑将private async void btcount_Click(object sender, RoutedEventArgs e) { var data = await api.getAPI("mylocaluri"); var msg = JsonConvert.DeserializeObject<myclassname>(data.ToString());//convert the string response in json format validate.DataContext = msg;// assign the data received to stackpanel }重命名为getAPI，然后关注common naming patterns。

模拟器挂起任务状态WaitingForActivation

1 个答案: