C# WPF 自學 MVVM簡單介紹

一、MVVM介紹

MVVM是Model-View-ViewModel（模型-視圖-視圖模型）的縮寫形式

 

 

　1、View就是用xaml實現的界面，負責與用戶交互，接收用戶輸入，把數據展現給用戶。

　2、ViewModel是一個C#類，負責收集需要綁定的數據和命令，聚合Model對象，通過View類的DataContext屬性綁定到View，同時也可以處理一些UI邏輯。

　3、Model，就是系統中的對象，可包含屬性和行為。

　三者之間的關系：View對應一個ViewModel，ViewModel可以聚合N個Model，ViewModel可以對應多個View

 

二、MVVM的優勢

　　三權分立。另外，和面向接口編程的思想有點相同；也和 asp.net mvc 有點像。

三、MVVM簡單示例

　　1.項目結構

 

 

 

我個人喜歡先寫 Model，再寫 ViewModel， 最后在 xaml 里面綁定數據

Model: UserInfo

 

 

 代碼：

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; }
    }
}

 

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 = "張三", 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);
        }




    }
}

 

 

在 MainWindow.xaml 中 聲明一個 ViewModel，就像 asp.net mvc 從后端把數據傳給視圖一樣。

 

 

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;
        }
    }
}

 

 

 

 

 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="年齡" HorizontalAlignment="Left" Margin="122,108,0,0" VerticalAlignment="Top"/>

    </Grid>
</Window>

 

Done!

 

最近在了解工控方面的編程，發現WPF搞工控開發很好。

QQ：77915862

有興趣的可以一起交流。