C# WPF 自学 MVVM简单介绍

一、MVVM介绍

MVVM是Model-View-ViewModel（模型-视图-视图模型）的缩写形式

　1、View就是用xaml实现的界面，负责与用户交互，接收用户输入，把数据展现给用户。

　2、ViewModel是一个C#类，负责收集需要绑定的数据和命令，聚合Model对象，通过View类的DataContext属性绑定到View，同时也可以处理一些UI逻辑。

　3、Model，就是系统中的对象，可包含属性和行为。

　三者之间的关系：View对应一个ViewModel，ViewModel可以聚合N个Model，ViewModel可以对应多个View

二、MVVM的优势

　　三权分立。另外，和面向接口编程的思想有点相同；也和 asp.net mvc 有点像。

三、MVVM简单示例

　　1.项目结构

我个人喜欢先写 Model，再写 ViewModel， 最后在 xaml 里面绑定数据

Model: UserInfo

代码：

using System;
using System.Collections.Generic;
using System.Text;

namespace WpfMVVMDemo.Model
{
  public  class UserInfo
    {
        private String _Name;
        private int _Age;
        public string Name { get => _Name; set => _Name = value; }
        public int Age { get => _Age; set => _Age = value; }
    }
}

UserInfo

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using WpfMVVMDemo.Model;

namespace WpfMVVMDemo
{
    public class UserInfoViewModel : INotifyPropertyChanged
    {
        private UserInfo userInfo;

        public UserInfoViewModel()
        {
            this.userInfo = new UserInfo() { Name = "张三", Age = 18 };
        }

        public String Name
        {
            get { return this.userInfo.Name; }
            set
            {
                this.userInfo.Name = value;
                RaisePropertyChanged("Name");
            }
        }

        public int Age
        {
            get { return this.userInfo.Age; }
            set
            {
                this.userInfo.Age = value;
                RaisePropertyChanged("Age");
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void RaisePropertyChanged(String propertyName)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }

        protected virtual void SetAndNotifyIfChanged<T>(String propertyName, ref T oldVal, ref T newVal)
        {
            if (oldVal == null && newVal == null) return;
            if (oldVal != null && oldVal.Equals(newVal)) return;
            if (newVal != null && newVal.Equals(oldVal)) return;
            oldVal = newVal;
            RaisePropertyChanged(propertyName);
        }

    }
}

UserInfoViewModel

在 MainWindow.xaml 中 声明一个 ViewModel，就像 asp.net mvc 从后端把数据传给视图一样。

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 WpfMVVMDemo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        UserInfoViewModel viewModel = new UserInfoViewModel();
        public MainWindow()
        {
            InitializeComponent();
            this.viewModel = base.DataContext as UserInfoViewModel;
        }
    }
}

MainWindow.xaml.cs

修改 xaml:

<Window x:Class="WpfMVVMDemo.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:WpfMVVMDemo"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Window.DataContext>
        <local:UserInfoViewModel></local:UserInfoViewModel>
    </Window.DataContext>
    <Grid>
        <TextBox Text="{Binding Name}" HorizontalAlignment="Left" Margin="176,82,0,0"  TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label Content="姓名" HorizontalAlignment="Left" Margin="122,78,0,0" VerticalAlignment="Top"/>
        <TextBox Text="{Binding Age}" HorizontalAlignment="Left" Margin="176,112,0,0"  TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label Content="年龄" HorizontalAlignment="Left" Margin="122,108,0,0" VerticalAlignment="Top"/>

    </Grid>
</Window>

MainWindow.xaml

Done!

最近在了解工控方面的编程，发现WPF搞工控开发很好。

QQ：77915862

有兴趣的可以一起交流。