Question

我遵循我的应用程序的MVVM模式并防止内存泄漏，我需要将对象实例的数量减少到一个。然后，应该将该对象实例交给其他需要的类。

在我当前的实现中，实例正在AppVM中设置，并传递给AdductionAbductionFlexionViewModel。但是，通过搜索MyoDeviceModle()实例，AdductionAbductionFlexionView中会显示第二个实例。

我的问题是如何在AdductionAbductionFlexionView中设置构造函数以获取在整个应用中使用的_connectedDevice实例？

这是AppVM，显示了应该使用的唯一实例：

private MyoDeviceModel _connectedDevice;

        #endregion

        /// <summary>
        /// Initializes a new instance of the <see cref="ApplicationViewModel"/> class.
        /// </summary>
        public ApplicationViewModel()
        {
            _connectedDevice = new MyoDeviceModel();
            // Add available pages
            PageViewModels.Add(new HomeViewModel(new UserLoginModel()));
            PageViewModels.Add(new AdductionAbductionFlexionViewModel(_connectedDevice, new DatabaseModel()));


            // Set starting page
            CurrentPageViewModel = PageViewModels[0];
        }

这就是它传递给AdductionAbductionFlexionViewModel：

的方式私人MyoDeviceModel _myoDevice; private DatabaseModel _dataObj;

public event Action<string> DataChanged;

private string _itemString;


/// <summary>
/// Initializes a new instance of the <see cref="AdductionAbductionFlexionViewModel"/> class.
/// </summary>
/// <param name="Myodevice">The device.</param>
/// <param name="progressData">The progress data.</param>
public AdductionAbductionFlexionViewModel(MyoDeviceModel Myodevice, DatabaseModel progressData)
{

    DataSubmitCommand = new RelayCommand (this.SaveChangesToPersistence);
    CalibrationSetCommand = new RelayCommand(this.CallibratePitchMinimumCall);
    DatabaseSearchCommand = new RelayCommand(this.QueryDataFromPersistence);

    _myoDevice = Myodevice;
    _myoDevice.MyoDeviceStart();

    _dataObj = progressData;

    _myoDevice.StatusUpdated += (update) =>
    {
        CurrentStatus = update;   
    };


    _myoDevice.PoseUpdated += (update) =>
    {
        PoseStatus = update;   
    };


    _myoDevice.PainfulArcDegreeUpdated += (update) =>
    {
        PainfulArcStatus = update;
    };


    _myoDevice.DegreesUpdated += (update) =>
    {
        DegreeStatus = update;
    };

    _myoDevice.StartDegreeUpdated += (update) =>
    {
        StartDegreeStatus = update;    
    };

    _myoDevice.EndDegreeUpdated += (update) =>
    {
        EndDegreeStatus = update;    
    };


}

但我想知道如何通过_connectedDevice实例代替new MyoDeviceModel()

        public AdductionAbductionFlexionView()
        {
            InitializeComponent();
            this.DataContext = new AdductionAbductionFlexionViewModel(new MyoDeviceModel(), new DatabaseModel()); 
            this.Loaded += AdductionAbductionFlexionView_Loaded;
            this.Loaded -= AdductionAbductionFlexionView_Loaded;

            ((AdductionAbductionFlexionViewModel)DataContext).DataChanged += x =>
            {

                new ToastPopUp("Submit Succeeded!", "Progress data submitted succesfully", NotificationType.Information)
                {
                    Background = new LinearGradientBrush(System.Windows.Media.Color.FromRgb(0, 189, 222), System.Windows.Media.Color.FromArgb(255, 10, 13, 248), 90),
                    BorderBrush = new SolidColorBrush(System.Windows.Media.Color.FromRgb(0, 189, 222)),
                    FontColor = new SolidColorBrush(System.Windows.Media.Color.FromRgb(255, 255, 255))
                }.Show();

            };

        }

Answer 1

您正在将初始实例传递给另一个类的构造函数。因此，您只使用一个实例而不是两个实例。如果您不想传递实例，则需要查看实现Singleton Pattern。

如何为应用程序设置单个对象实例？

1 个答案: