WPF的UserControl的MVVM模式赋值

背景说明

项目日常应用，经常会使用到UserConrol来进行组合形成组合控件，组合控件在使用过程中，必然需要进行赋值，当前案例是UserControl中label的定时赋值。

技术分析

1.分离关注点：MVVM 模式将应用程序分为三个主要部分，即模型（Model）、视图（View）和视图模型（ViewModel）。在这个例子中，MyUserControlViewModel 和 MainViewModel 充当 ViewModel，负责处理业务逻辑和数据操作；MyUserControl.xaml 和 MainWindow.xaml 是 View，负责呈现用户界面；而数据本身则相当于 Model。这种分离使得代码结构更加清晰，易于维护和测试。

2.属性更改通知：ViewModel 实现了 INotifyPropertyChanged 接口，当 ViewModel 中的属性值发生变化时，会触发 PropertyChanged 事件，通知视图更新相应的显示内容。这是 MVVM 模式中实现数据绑定自动更新的关键技术。

代码

UserControl的xaml

UserControl的cs

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;

namespace UserControlLabelsShow
{
    /// 

    /// UserControl1.xaml 的交互逻辑
    /// 
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
            DataContext = new UserControl1ViewModel();
        }
    }
}

UserControl1ViewModel

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace UserControlLabelsShow
{
    public class UserControl1ViewModel:Notify
    {
        private int _label1Value;
        private int _label2Value;
        private int _label3Value;
        private int _label4Value;
        private int _label5Value;

        public int Label1Value
        {
            get { return _label1Value; }
            set
            {
                if (_label1Value != value)
                {
                    _label1Value = value;
                    OnPropertyChanged(nameof(Label1Value));
                }
            }
        }

        public int Label2Value
        {
            get { return _label2Value; }
            set
            {
                if (_label2Value != value)
                {
                    _label2Value = value;
                    OnPropertyChanged(nameof(Label2Value));
                }
            }
        }

        public int Label3Value
        {
            get { return _label3Value; }
            set
            {
                if (_label3Value != value)
                {
                    _label3Value = value;
                    OnPropertyChanged(nameof(Label3Value));
                }
            }
        }

        public int Label4Value
        {
            get { return _label4Value; }
            set
            {
                if (_label4Value != value)
                {
                    _label4Value = value;
                    OnPropertyChanged(nameof(Label4Value));
                }
            }
        }

        public int Label5Value
        {
            get { return _label5Value; }
            set 
            {
                if (_label5Value != value)
                {
                    _label5Value = value;
                    OnPropertyChanged(nameof(Label5Value));
                }
            }
        }

      

    }
}

MainWindowViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;

namespace UserControlLabelsShow
{
    public class MainWindowViewModel: Notify
    {

        public UserControl1ViewModel UserControl1ViewModel { get; set; }
        public UserControl1ViewModel UserControl2ViewModel { get; set; }
        public UserControl1ViewModel UserControl3ViewModel { get; set; }
        public UserControl1ViewModel UserControl4ViewModel { get; set; }


        private Timer _timer;

        public MainWindowViewModel()
        {
            UserControl1ViewModel = new UserControl1ViewModel();
            UserControl2ViewModel = new UserControl1ViewModel();
            UserControl3ViewModel = new UserControl1ViewModel();
            UserControl4ViewModel = new UserControl1ViewModel();

            _timer = new Timer(TimerCallback, null, TimeSpan.Zero, TimeSpan.FromSeconds(1));
        }



        private void TimerCallback(object state)
        {
            Application.Current.Dispatcher.Invoke(() =>
            {
                // 第一个 UserControl 赋值
                UserControl1ViewModel.Label1Value++;
                UserControl1ViewModel.Label2Value++;
                UserControl1ViewModel.Label3Value++;
                UserControl1ViewModel.Label4Value++;
                UserControl1ViewModel.Label5Value++;

                // 第二个 UserControl 赋值
                UserControl2ViewModel.Label1Value = UserControl2ViewModel.Label1Value + 100;
                UserControl2ViewModel.Label2Value = UserControl2ViewModel.Label2Value + 100;
                UserControl2ViewModel.Label3Value = UserControl2ViewModel.Label3Value + 100;
                UserControl2ViewModel.Label4Value = UserControl2ViewModel.Label4Value + 100;
                UserControl2ViewModel.Label5Value = UserControl2ViewModel.Label5Value + 100;

                // 第三个 UserControl 赋值
                UserControl3ViewModel.Label1Value = UserControl3ViewModel.Label1Value + 200;
                UserControl3ViewModel.Label2Value = UserControl3ViewModel.Label2Value + 200;
                UserControl3ViewModel.Label3Value = UserControl3ViewModel.Label3Value + 200;
                UserControl3ViewModel.Label4Value = UserControl3ViewModel.Label4Value + 200;
                UserControl3ViewModel.Label5Value = UserControl3ViewModel.Label5Value + 200;

                // 第四个 UserControl 赋值
                UserControl4ViewModel.Label1Value = UserControl4ViewModel.Label1Value + 300;
                UserControl4ViewModel.Label2Value = UserControl4ViewModel.Label2Value + 300;
                UserControl4ViewModel.Label3Value = UserControl4ViewModel.Label3Value + 300;
                UserControl4ViewModel.Label4Value = UserControl4ViewModel.Label4Value + 300;
                UserControl4ViewModel.Label5Value = UserControl4ViewModel.Label5Value + 300;
            });
        }
    }
}

MainWindow.xaml

MainWindow.cs

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;

namespace UserControlLabelsShow
{
    /// 

    /// MainWindow.xaml 的交互逻辑
    /// 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            DataContext = new MainWindowViewModel();

        }
    }
}

辅助类MyCommand

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace UserControlLabelsShow
{
    public class MyCommand:ICommand
    {
        private readonly Action _execute;
        private readonly Func _canExecute;

        public MyCommand(Action execute, Func canExecute = null)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute;
        }

        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute == null || _canExecute();
        }

        public void Execute(object parameter)
        {
            _execute();
        }



    }
}

辅助类Notify

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;

namespace UserControlLabelsShow
{
    public abstract class Notify : INotifyPropertyChanged
    {

        public event PropertyChangedEventHandler PropertyChanged;

        public void OnPropertyChanged([CallerMemberName] string name = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
        }

    }
}