c# - 将异步任务响应转换为字符串

Question

首先，我想说，我是 C# 的新手。

我正在尝试创建一个 POST 请求，该请求将一些数据发送到不同服务器上某处的 PHP 文件。

现在，请求发送后我想看到响应，因为我从服务器发回一个 JSON 字符串作为成功消息。

当我使用下面的代码时:

public MainPage()
{

     this.InitializeComponent();
     Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().SetDesiredBoundsMode(Windows.UI.ViewManagement.ApplicationViewBoundsMode.UseCoreWindow);

     responseBlockTxt.Text = start();
}

public string start()
{
    var response = sendRequest();

    System.Diagnostics.Debug.WriteLine(response);

    return "";
}

public async Task<string> sendRequest()
{
     using (var client = new HttpClient())
     {
          var values = new Dictionary<string, string>
          {
               { "vote", "true" },
               { "slug", "the-slug" }
          };

          var content = new FormUrlEncodedContent(values);

          var response = await client.PostAsync("URL/api.php", content);

          var responseString = await response.Content.ReadAsStringAsync();

          return responseString;
      }

}

输出是:

System.Threading.Tasks.Task`1[System.String]

那么，我如何才能看到所有的结果呢？

Answer 1

一路走异步。调用异步方法时避免阻塞调用。 async void 允许在事件处理程序中更新页面以执行加载事件调用

继续阅读 Async/Await - Best Practices in Asynchronous Programming

然后相应地更新你的代码

public MainPage() {    
    this.InitializeComponent();
    Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().SetDesiredBoundsMode(Windows.UI.ViewManagement.ApplicationViewBoundsMode.UseCoreWindow);
    this.Loaded += OnLoaded;     
}

public async void OnLoaded(object sender, RoutedEventArgs e) {
    responseBlockTxt.Text = await start();
}

public async Task<string> start() {
    var response = await sendRequest();

    System.Diagnostics.Debug.WriteLine(response);

    return response;
}

private static HttpClient client = new HttpClient();

public async Task<string> sendRequest() {
    var values = new Dictionary<string, string> {
        { "vote", "true" },
        { "slug", "the-slug" }
    };

    var content = new FormUrlEncodedContent(values);
    using(var response = await client.PostAsync("URL/api.php", content)) {
        var responseString = await response.Content.ReadAsStringAsync();
        return responseString;
    }
}