免責(zé)聲明：我真的是WPF的新手。在網(wǎng)上瀏覽后，我了解到HttpClient應(yīng)該用作WPF中Windows之間共享的單例。但是，我似乎找不到在MVC中找到的清晰的啟動(dòng)入口點(diǎn)（啟動(dòng)，du?。?。我應(yīng)該在哪里實(shí)例化HttpClient，如何在多個(gè)窗口中使用它？目前我有兩個(gè)窗戶。登錄名和MainWindow。兩者都非?；A(chǔ)。例子：public partial class Login : Window{    public Login()    {        InitializeComponent();    }    private void BtnLoginSubmit_Click(object sender, RoutedEventArgs e)    {    }}在我的App.xaml.cs中，我實(shí)例化了一個(gè)HttpClient對(duì)象，可以從我的MainWindow訪問該對(duì)象：App.xaml.cs：public partial class App : Application{    public HttpClient httpClient { get; set; }}MainWindow.xaml.cs：public partial class MainWindow : Window    {        private static ObservableCollection<string> states;        public static void Add(string state)        {            states.Add(state);        }         public MainWindow()        {            InitializeComponent();            ((App)Application.Current).httpClient = new HttpClient();            states = new ObservableCollection<string>();            states.Add("Initialized");            states.CollectionChanged += states_CollectionChanged;            LblStates.ItemsSource = states;            Microsoft.Win32.SystemEvents.SessionSwitch += new Microsoft.Win32.SessionSwitchEventHandler(SystemEvents_SessionSwitch);        }        static void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)        {            if (e.Reason == SessionSwitchReason.SessionLock)            {            }            MainWindow.Add(e.Reason.ToString());        }        void states_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)        {            if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)            {                LblStates.Items.Refresh();            }        }    }