無法在Xamarin android的Portable類庫中使用wcf服務POST方法

Question

我正在使用Visual Studio中的可移植類庫中的wcf webservices（POST方法）for xamarin android.App在POST方法中崩潰.Below是我的代碼

在PCL

將Class1.cs

namespace XamarinServiceCall
{
    public sealed class Class1 : IRestService
    {

        public async Task<string> GetData(UserModel model)
        {
            using (var client = new HttpClient())
            {
                var content = new StringContent(JsonConvert.SerializeObject(model), Encoding.UTF8, "application/json");

                var result = await client.PostAsync("http://xamarin-rest-service/LoginService/ValidateLogin", content);
                return await result.Content.ReadAsStringAsync();

            }
        }
    }
}

IRestService.cs

namespace XamarinServiceCall
{
    public interface IRestService
    {
        Task<string> GetData(UserModel model);
    }
}

UserModel.cs

public class UserModel
    {

        public string loginFrom { get; set; }

        public string domainName { get; set; }
        public string userName { get; set; }
        public string password { get; set; }

        //I get response of below parameters
        public int DomainType { get; set; }
        public string FirstName { get; set; }

        public int Status { get; set; }
        public int UserId { get; set; }
      }

在Xamarin Android APp中

MainActivity.cs

namespace ServiceSample
{
    [Activity(Label = "LayoutSample", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : Activity
    {
            protected async override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            // Get our button from the layout resource,
            // and attach an event to it
            Button button = FindViewById<Button>(Resource.Id.MyButton);

            XamarinServiceCall.Class1 serviceClass = new XamarinServiceCall.Class1();
           var model = new XamarinServiceCall.UserModel { domainName = "domainname" ,userName = "username" , password = "password" ,loginFrom = "App" };

            var result = await serviceClass.GetData(model);
            button.Text = "get call says: " + result;

        }
    }
}

郵遞員回應：

當我調試時，我在結果變量中得到此響應。

當我指向postAsync Function時，它顯示Expression無效

Answer 1

您不應該嘗試在MainActivity的OnCreate函數中執行任何重要的工作，例如調用Web服務。

當然，你不應該讓它異步並在其中進行異步調用。 請查看Xamarin的例子。

通常，可以在OnCreate中進行一些初始化，然后為Application類（可以在PCL項目中定義）調用LoadApplication。