WPF MVVM实例三

在没给大家讲解wpf mwm示例之前先给大家简单说下MVVM理论知识：

WPF技术的主要特点是数据驱动UI,所以在使用WPF技术开发的过程中是以数据为核心的，WPF提供了数据绑定机制，当数据发生变化时，WPF会自动发出通知去更新UI。

　　我们使用模式，一般是想达到高内聚低耦合。在WPF开发中，经典的编程模式是MVVM，是为WPF量身定做的模式，该模式充分利用了WPF的数据绑定机制，最大限度地降低了Xmal文件和CS文件的耦合度，也就是UI显示和逻辑代码的耦合度，如需要更换界面时，逻辑代码修改很少，甚至不用修改。与WinForm开发相比，我们一般在后置代码中会使用控件的名字来操作控件的属性来更新UI，而在WPF中通常是通过数据绑定来更新UI；在响应用户操作上，WinForm是通过控件的事件来处理，而WPF可以使用命令绑定的方式来处理，耦合度将降低。

首先MVVM设计模式的结构

Views: 由Window/Page/UserControl等构成，通过DataBinding与ViewModels建立关联；
ViewModels：由一组命令，可以绑定的属性，操作逻辑构成；因为View与ViewModel进行了解耦，我们可以对ViewModel进行Unit Test；

Models：可以是实体对象或者Web服务；
下面通过一个简单的例子，来介绍一些WPF MVVM模式。首先项目结构：

DelegateCommand.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WpfApp13.Commands;
 
namespace WpfApp13.ViewModels
{
    class MainWindowViewModel:NotificationObject
    {
        private double  input1;
 
        public double Input1
        {
            get { return input1; }
            set
            {
                input1 = value;
                this.RaisePropertyChange("Input1");
            }
        }
 
        private double input2;
 
        public double Input2
        {
            get { return input2; }
            set
            {
                input2 = value;
                this.RaisePropertyChange("Input2");
            }
        }
 
        private double result;
 
        public double Result
        {
            get { return result; }
            set
            {
                result = value;
                this.RaisePropertyChange("Result");
            }
        }
 
        public DelegateCommand AddCommand { get; set; }
 
        public void Add(object parameter)
        {
            this.Result = this.Input1 + this.Input2;
        }
 
        public MainWindowViewModel()
        {
            this.AddCommand = new DelegateCommand();
            this.AddCommand.ExcuteAction = new Action<object>(this.Add);
        }
    }
}

　　MainWindowViewModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WpfApp13.Commands;
 
namespace WpfApp13.ViewModels
{
    class MainWindowViewModel:NotificationObject
    {
        private double  input1;
 
        public double Input1
        {
            get { return input1; }
            set
            {
                input1 = value;
                this.RaisePropertyChange("Input1");
            }
        }
 
        private double input2;
 
        public double Input2
        {
            get { return input2; }
            set
            {
                input2 = value;
                this.RaisePropertyChange("Input2");
            }
        }
 
        private double result;
 
        public double Result
        {
            get { return result; }
            set
            {
                result = value;
                this.RaisePropertyChange("Result");
            }
        }
 
        public DelegateCommand AddCommand { get; set; }
 
        public void Add(object parameter)
        {
            this.Result = this.Input1 + this.Input2;
        }
 
        public MainWindowViewModel()
        {
            this.AddCommand = new DelegateCommand();
            this.AddCommand.ExcuteAction = new Action<object>(this.Add);
        }
    }
}

　　NotificationObject.CS

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace WpfApp13.ViewModels
{
    class NotificationObject : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;
 
        public void RaisePropertyChange(string propertyName)
        {
            if(this.PropertyChanged!=null)
            {
                this.PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}

　　MainWindow.xaml.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;
using WpfApp13.ViewModels;
 
namespace WpfApp13
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.DataContext = new MainWindowViewModel();
        }
 
        
 
    }
 
    
 
}
 
MainWindow.xaml

<Window x:Class="WpfApp13.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:WpfApp13"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <StackPanel>
            <Slider Name="slider1" MinHeight="25" Value="{Binding Input1}"/>
            <Slider Name="slider2" MinHeight="25" Value="{Binding Input2}"/>
            <Slider Name="slider3" MinHeight="25" Value="{Binding Result}"/>
            <Button Name="addButton" Content="ADD" FontSize="30" MinHeight="40" Command="{Binding AddCommand}"/>
        </StackPanel>     
    </Grid>
</Window>