网络教学网站建设北京定制网站开发公司浩森宇特

简单的计数案例，ViewModel开启辅助线程，模拟后端运行，该方式可以扩展为项目中的后端线程数采及运算呈现，便于实时监控数据的场景。

代码如下：

MyCommand

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;namespace MVVMCountDemo.ViewModel
{public class MyCommand : ICommand{private readonly Action _execute;private readonly Func<bool> _canExecute;public MyCommand(Action execute, Func<bool> canExecute = null){_execute = execute;}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();}}
}

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 MVVMCountDemo.ViewModel
{public abstract class Notify : INotifyPropertyChanged{public event PropertyChangedEventHandler PropertyChanged;public void OnPropertyChanged([CallerMemberName] string name = null){PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));}}
}

Window.xaml

<Window x:Class="MVVMCountDemo.MainWindow"xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:d="http://schemas.microsoft.com/expression/blend/2008"xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"xmlns:local="clr-namespace:MVVMCountDemo"mc:Ignorable="d"Title="MainWindow" Height="350" Width="525"><Grid><Label  FontSize="30" Content="{Binding Seconds}"   Foreground="Black" HorizontalAlignment="Left" Margin="141,85,0,0" VerticalAlignment="Top" Height="110" Width="230"/><Button Content="开始/清零" HorizontalAlignment="Left" Margin="203,224,0,0" VerticalAlignment="Top" Width="100" Command="{Binding StartOrResetCommand}"/></Grid>
</Window>

MainWindow.cs

using MVVMCountDemo.ViewModel;
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 MVVMCountDemo
{/// <summary>/// MainWindow.xaml 的交互逻辑/// </summary>public partial class MainWindow : Window{public MainWindow(){InitializeComponent();this.DataContext = new CountDemoViewModel();}}
}

CountDemoViewModel 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;
using System.Windows.Threading;namespace MVVMCountDemo.ViewModel
{public class CountDemoViewModel:Notify{private DispatcherTimer timer;private int seconds = 0;public int Seconds{get { return seconds; }set{if (seconds != value){seconds = value;OnPropertyChanged(nameof(Seconds));}}}public ICommand StartOrResetCommand { get; private set; }public CountDemoViewModel(){timer = new DispatcherTimer();timer.Interval = TimeSpan.FromSeconds(1);timer.Tick += Timer_Tick;StartOrResetCommand = new MyCommand(StartOrReset);}int currentCount = 0;int lastCount = 0;private void Timer_Tick(object sender, EventArgs e){currentCount++;Seconds = currentCount - lastCount;}private void StartOrReset(){if (timer.IsEnabled){timer.Stop();Seconds = 0;lastCount = currentCount;}else{timer.Start();}}}
}