WPF> WEBAPI> HttpClient> AWAIT = UI延迟

4 回答

• 1

  @ Stef7和@Panagiotis - 你们是对的，UI线程被阻止了 . 我不确定我理解为什么异步调用会阻止UI线程;我将不得不做更多的研究 .

  我已经尝试了一个后台线程但直到我在Task上实现了ContinueWith才解决了我的问题 .

  谢谢您的帮助 .

  这是最终的代码 .

  public partial class Splash : Window
  {
      private TypeBO boType = new TypeBO();
      private Stopwatch swTotal = new Stopwatch();
      private Stopwatch swData= new Stopwatch();
  
      public Splash()
      {
          InitializeComponent();
          swTotal.Start();
      }
  
      private void GetData()
      {
          Assembly assembly = Assembly.GetExecutingAssembly();
          lblMessage.Content = "Please Wait...";
          lblVersion.Content = "Version: " + assembly.GetName().Version.Major + "." + assembly.GetName().Version.Minor + "." + assembly.GetName().Version.Revision;
  
          swData.Start();
  
          var backgroundWorker = new BackgroundWorker();
          backgroundWorker.DoWork += this.OnBackgroundWorkerDoWork;
          backgroundWorker.RunWorkerCompleted += OnBackgroundWorkerRunWorkerCompleted;
          backgroundWorker.RunWorkerAsync();
      }
  
      private void OnBackgroundWorkerDoWork(object sender, DoWorkEventArgs e)
      {
          WEBAPI.GetHttpClient().GetAsync("api/COStateType/GetStateTypesByCountryID/"
              + Constants.COUNTRY_ID_USA).ContinueWith(r =>
              {
                  r.Result.EnsureSuccessStatusCode();
                  e.Result = r.Result.Content.ReadAsAsync<List<coStateType>>().Result;
              }).Wait();
  
          swData.Stop();
          System.Diagnostics.Debug.Write("Splash - DATA - Total Elapsed Time - " + swData.Elapsed + Environment.NewLine);
      }
  
      private void OnBackgroundWorkerRunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
      {
          var backgroundWorker = sender as BackgroundWorker;
          backgroundWorker.DoWork -= this.OnBackgroundWorkerDoWork;
          backgroundWorker.RunWorkerCompleted -= OnBackgroundWorkerRunWorkerCompleted;
  
          App.stateTypes = e.Result as List<coStateType>;
  
          coStateType pleaseSelectStateType = new coStateType() { State_ID = 0, State_Nm = "Select One", Country_ID = 1 };
          App.stateTypes.Insert(0, pleaseSelectStateType);
  
          sbHideState.Completed += (snd, eva) =>
          {
              //Pre-Load User Controls
              Assembly assembly = this.GetType().Assembly;
              UserControl ucBHSearch = (UserControl)assembly.CreateInstance(string.Format("{0}.BHSearch", "ABS2.WPF.ADMIN.UserControls.BusinessHierarchy"));
              UserControl ucBHDetails = (UserControl)assembly.CreateInstance(string.Format("{0}.BHDetails", "ABS2.WPF.ADMIN.UserControls.BusinessHierarchy"));
              App.userControls.Add("BHD", ucBHDetails);
              App.userControls.Add("BHS", ucBHSearch);
  
              Login winLogin = new Login();
              winLogin.Show();
  
              swTotal.Stop();
              System.Diagnostics.Debug.Write("Splash - UI - Total Elapsed Time - " + swTotal.Elapsed + Environment.NewLine + Environment.NewLine);
              swTotal.Reset();
              this.Close();
          };
          sbHideState.Begin(gridSplash);
      }
  
      private void Window_Loaded_1(object sender, RoutedEventArgs e)
      {
          lblMessage.Content = "";
          lblVersion.Content = "";
          sbDefaultState.Begin(gridSplash);
          sbRotateState.Begin(gridSplash);           
      }
  
      private void window_ContentRendered(object sender, EventArgs e)
      {
          sbShowState.Completed += (snd, eva) =>
          {
              GetData();
          };
          sbShowState.Begin(gridSplash);
      }
  }
  

  回复于 2024-04-30T14:14:37+08:00
• 2

  当await完成等待时，在原始上下文（线程）中继续执行，在您的情况下是UI线程 .

  这允许您的代码在不使用调度程序的情况下访问UI控件 . 这意味着在最后一次等待之后的任何昂贵的代码实际上将在UI线程上运行 .

  如果希望代码继续在单独的线程上运行，则应在调用await之后添加.ConfigureAwait（false），即 .

  await response.Content.ReadAsAsync<List<coStateType>>().ConfigureAwait(false);
  

  在这种情况下，您应该注意使用Dispatcher或SynchronizationContext方法Post / Send来访问UI控件，例如 .

  SynchronizationContext.Current.Post(_=>progressBar.Value+=5,null);
  

  回复于 2024-04-30T14:14:37+08:00
• 1

  您发布的所有代码都在UI线程中执行 . 异步功能可以帮助您在没有任何操作（Web请求期间）时阻止UI线程，但如果您让UI线程忙于处理太多代码，则动画将始终出现问题 .

  我会尝试将所有与Web相关的代码移动到后台工作程序中，并仅向UI线程发布简短的UI更新 . 既然你写过你已经尝试了后台工作者，我必须假设UI更新花了太长时间 .

  如果您有性能分析器，请分析UI线程的繁忙时间以获得更好的画面 .

  回复于 2024-04-30T14:14:37+08:00
• 1

  你需要使用“任务”功能来调用异步 . 这不会阻止您的GUI主线程，也不需要使用后台工作程序或线程 . “任务”，“异步”，“等待”一起去 .

  回复于 2024-04-30T14:14:37+08:00