Question

我正在使用以下步骤构建xamarin跨平台便携式应用程序：

添加了服务参考。
点击按钮点击登录页面，我用来验证来自db的用户，如果成功，则转到下一页，否则显示消息。

这是代码。

Login.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="FypXFP.Login">
    <ContentPage.Content>

        <StackLayout>
            <Label Text="UserName" />
            <Entry x:Name="tbuserentry" Placeholder="UserName"></Entry>
            <Label Text="Password"></Label>
            <Entry x:Name="Pwd" IsPassword="True" Placeholder="Password"></Entry>
            <Button x:Name="Save" Clicked="Save_Clicked" Text="Login"></Button>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

Login.cs.xaml

using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace FypXFP
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class Login : ContentPage
    {
        private FypXFP.ServiceReference1.CMSServiceClient _client;
        public Login()
        {
            InitializeComponent();
        }

        private void Save_Clicked(object sender, EventArgs e)
        {
            var endpoint = new EndpointAddress("http://192.168.43.101/FYP_Admin/webservices/cmsservice.svc");
            var binding = new BasicHttpBinding
            {
                Name = "basicHttpBinding",
                MaxBufferSize = 2147483647,
                MaxReceivedMessageSize = 2147483647
            };

            TimeSpan timeout = new TimeSpan(0, 0, 30);
            binding.SendTimeout = timeout;
            binding.OpenTimeout = timeout;
            binding.ReceiveTimeout = timeout;

            _client = new FypXFP.ServiceReference1.CMSServiceClient(binding, endpoint);

            string uname = tbuserentry.Text.Trim();
            string password = Pwd.Text.Trim();
            _client.ValidateUserAsync(uname, password);
            _client.ValidateUserCompleted += _client_ValidateUserCompleted;

        }
        public async void Redirect(Boolean Result)
        {
            if (Result == true)
            {
                Navigation.InsertPageBefore(new TicketPage(), this);
                await Navigation.PopAsync();
            }
            else
            {
                await DisplayAlert("Alert", "Something wrong", "Cancel");
            }
        }
        private void _client_ValidateUserCompleted(object sender, ServiceReference1.ValidateUserCompletedEventArgs e)
        {
            if (e.Result == true)
            {
                Device.BeginInvokeOnMainThread(() => {
                    Redirect(true);
                });


            }
            else
            {
                Device.BeginInvokeOnMainThread(() => {
                    Redirect(false);
                });
            }
        }
    }
}

问题是如果我输入了错误的凭据，而不是警报显示，但另一方面，如果输入了正确的凭据，则显示

取消处理例外

我已尝试过所有可能的解决方案。

如何在Xamarin跨平台应用程序中导航？

0 个答案: