内容说明：视频教程总结

代码平台：visual  studio  2019

内容简介：使用wpf的MVVM框架（view-model -viewmodel）实现简单数据绑定及行为绑定，实现前后端代码的分离; 实例为两个数相加，并显示计算结果。

1.view---MainWindow.xaml

<Window x:Class="MVVMdemo.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:MVVMdemo"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800" ShowInTaskbar="True" WindowStartupLocation="CenterScreen" WindowState="Maximized" Topmost="True"  >
    <Grid>
       
        
        <TextBox HorizontalAlignment="Left" Height="23" Margin="158,84,0,0" TextWrapping="Wrap"  VerticalAlignment="Top" Width="120" Text="{Binding Input1}"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="158,130,0,0" TextWrapping="Wrap"  VerticalAlignment="Top" Width="120" Text="{Binding Input2}"/>
        <TextBox HorizontalAlignment="Left" Height="23" Margin="158,178,0,0" TextWrapping="Wrap"  VerticalAlignment="Top" Width="120" Text="{Binding Result}"/>
        <Button Content="add" HorizontalAlignment="Left" Margin="337,130,0,0" VerticalAlignment="Top" Width="75" Command="{Binding AddCommand}" Height="23"/>

    </Grid>
</Window>

 2.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 MVVMdemo
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = new MainWindowViewModel();
        }
    }
}

3.NotificationObject.cs

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

namespace MVVMdemo
{
    class NotificationObject : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
        public void RaisePropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
           
        }
    }
}

4.viewmodel---MainWindowViewModel.cs

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

namespace MVVMdemo
{
    class MainWindowViewModel:NotificationObject
    {
        //输入值1
        private double input1;

        public double Input1
        {
            get { return input1; }
            set
            {
                input1 = value;
                this.RaisePropertyChanged("Input1");
            }
        }
        private double input2;
        //输入值2
        public double Input2
        {
            get { return input2; }
            set
            {
                input2 = value;
                this.RaisePropertyChanged("Input2");
            }
        }
        //计算结果
        private double result;

        public double Result
        {
            get { return result; }
            set
            {
                result = value;
                this.RaisePropertyChanged("Result");
            }
        }
        //
        public DelegateCommand AddCommand { get; set; }
        private void Add(object parameter)
        {
            //计算代码段
            this.Result = this.Input1 + this.Input2;
        }
        public MainWindowViewModel()
        {
            this.AddCommand = new DelegateCommand();
            this.AddCommand.ExecuteAction = new Action<object>(this.Add);
        }

    }
}

5.DelegateCommand.cs

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

namespace MVVMdemo
{
    class DelegateCommand : ICommand
    {
        public event EventHandler CanExecuteChanged;

        public bool CanExecute(object parameter)
        {
           return true;
            //if (CanExecuteFunc == null)
            //{

            //}
            //this.CanExecuteFunc(parameter);
        }

        public void Execute(object parameter)
        {
            if (ExecuteAction == null)
            {
                return;
            }
            this.ExecuteAction(parameter);
        }       
        public Action<object> ExecuteAction { get; set; }
        public Func<object, bool> CanExecuteFunc { get; set; }
    }
}