Question

我在XAML应用上编写了这个简单的调用来尝试调用REST服务。

该程序似乎有效，但我遇到异步方法问题...我在小提琴手上看到我收到了令牌，但程序没有注意到..

我该如何解决？是否有最佳做法？

这是文件xaml.cs

背后的代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Newtonsoft.Json.Linq;
using System.Net.Http;
using System.Net.Http.Headers;


namespace CallRESTToken
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void button_Click(object sender, RoutedEventArgs e)
        {
            try
            {    
                const string userName = "user";
                const string password = "password";
                const string apiBaseUri = "http://example.com";
                const string apiGetPeoplePath = "/api/values";


                //Get the token
                var token = GetAPIToken(userName, password, apiBaseUri).Result;

                textBoxtoken.Text = (token);

                //Console.WriteLine("Token: {0}", token);

                //Make the call
                var response = GetRequest(token, apiBaseUri, apiGetPeoplePath).Result;

                textBox1view.Text = (response);
                //Console.WriteLine("response: {0}", response);

                //wait for key press to exit
                //Console.ReadKey();   
            }
            catch (Exception ex)
            {

                throw ex;
            }
        }

        private static async Task<string> GetAPIToken(string userName, string password, string apiBaseUri)
        {
            try
            {    
                using (var client = new HttpClient())
                {
                    //setup client
                    client.BaseAddress = new Uri(apiBaseUri);
                    client.DefaultRequestHeaders.Accept.Clear();
                    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

                    //setup login data
                    var formContent = new FormUrlEncodedContent(new[]
                    {
                         new KeyValuePair<string, string>("grant_type", "password"),
                         new KeyValuePair<string, string>("username", userName),
                         new KeyValuePair<string, string>("password", password),
                     });

                    //send request
                    HttpResponseMessage responseMessage = await client.PostAsync("/token", formContent);

                    //get access token from response body
                    var responseJson = await responseMessage.Content.ReadAsStringAsync();
                    var jObject = JObject.Parse(responseJson);
                    return jObject.GetValue("access_token").ToString();
                }

            }
            catch (Exception ex)
            {

                throw ex;
            }

        }

        static async Task<string> GetRequest(string token, string apiBaseUri, string requestPath)
        {
            try
            {             
                using (var client = new HttpClient())
                {
                    //setup client
                    client.BaseAddress = new Uri(apiBaseUri);
                    client.DefaultRequestHeaders.Accept.Clear();
                    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                    client.DefaultRequestHeaders.Add("Authorization", "Bearer " + token);

                    //make request
                    HttpResponseMessage response = await client.GetAsync(requestPath);
                    var responseString = await response.Content.ReadAsStringAsync();
                    return responseString;
                }
            }
            catch (Exception ex)
            {

                throw ex;
            }    
        }    
    }
}

Answer 1

您正在将async与.Result阻止来电混合。

更新事件处理程序以使用async / await并删除.Result阻止调用。事件处理程序是允许async void

的豁免案例

private async void button_Click(object sender, RoutedEventArgs e) {
    try {

        //... code removed for brevity

        //Get the token
        var token = await GetAPIToken(userName, password, apiBaseUri);

        //... code removed for brevity

       //Make the call
        var response = await GetRequest(token, apiBaseUri, apiGetPeoplePath);

        //... code removed for brevity

    } catch (Exception ex) {
        throw ex;
    }
}

阅读Async/Await - Best Practices in Asynchronous Programming

使用Autentication令牌进行REST调用

1 个答案: