WPF MVVM模式

1. MVVM

MVVM的设计模式最早于2005年由微软的WPF和Silverlight架构师John Gossman在他的博客中提到。

WPF中采用MVVM的架构可以获得以下好处:

1. 将UI和业务的设计完全分开，View只是ViewModel的消费者

2. 有助于我们区别并哪些是UI操作，哪些是业务操作，而不是将他们混淆

3.层与层之间耦合度降低,这一点非常符合面向对象(OOP)的思想。

2.MVVM 用图来表示，这个是从网上找的图,简单明了,省去了自己画。

 

3.下面来一步一步写代码吧!

3.1 在项目根目录创建Model文件夹,并新增一个实体类,PersonModel,实现INotifyPropertyChanged通知接口。

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

 namespace MVVMDemo.Model
 {
     public class Person : INotifyPropertyChanged
     {
         public event PropertyChangedEventHandler PropertyChanged;

         private string name = "吃饭了";
         public string Name
         {
             get { return name; }
             set { name = value; OnPropertyChanged("Name"); }
         }

         private void OnPropertyChanged(string propertyName)
         {
             if (PropertyChanged == null) return;
             PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
         }

         public void Show(object o)
         {
             this.Name += ",吃饭了";

         }
     }
 }

PersonModel

3.2 在项目根目录创建ViewModel文件夹,并新增一个PersonViewModel

 using MVVMDemo.Commands;
 using MVVMDemo.Model;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;

 namespace MVVMDemo.ViewModel
 {
    public class PersonViewModel
     {
         public PersonCommand PersonCommand { get; set; }
         public Person PersonModel { get; set; }

         public PersonViewModel()
         {
             this.PersonModel = new Person();
             this.PersonCommand = new PersonCommand();
             this.PersonCommand.ExecuteCommand = this.PersonModel.Show;

         }

     }
 }

PersonViewModel

3.3 在项目根目录创建Commands文件夹,并新增一个PersonCommand,实现ICommand接口。

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

 namespace MVVMDemo.Commands
 {
     public class PersonCommand : ICommand
     {
         public Func<object, bool> CanExecuteCommand = null;
         public Action<object> ExecuteCommand = null;

         public bool CanExecute(object parameter)
         {
             if (CanExecuteCommand == null) return true;
             return CanExecuteCommand(parameter);
         }

         public event EventHandler CanExecuteChanged;

         public void Execute(object parameter)
         {
             if (ExecuteCommand == null) return;
             ExecuteCommand(parameter);
         }

         public void OnCanExecuteChanged()
         {
             if (CanExecuteChanged == null) return;
             CanExecuteChanged(this, EventArgs.Empty);
         }
     }
 }

PersonCommand

3.4 MainWindow.xaml调用

 1 <Window x:Class="MVVMDemo.MainWindow"
 2         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         Title="MainWindow" Height="434.432" Width="607.471">
 5     <Grid Margin="0,0,2,5">
 6
 7         <TextBlock  Name="lbShow" Text="{Binding PersonModel.Name}" Margin="10,274,-10,10" />
 8         <Button Command="{Binding PersonCommand}" Height="20" Width="120" Margin="214,211,214,93" Content="MVVM"></Button>
 9        <!-- <Button  Height="20" Width="120" Content="{Binding ElementName=gb,Path=Value,UpdateSourceTrigger=PropertyChanged,Mode=OneWay}"></Button> -->
10     </Grid>
11 </Window>

 using MVVMDemo.ViewModel;
 using System.Windows;

 namespace MVVMDemo
 {
     /// <summary>
     /// MainWindow.xaml 的交互逻辑
     /// </summary>
     public partial class MainWindow : Window
     {
         public MainWindow()
         {
             InitializeComponent();
             this.DataContext = new PersonViewModel();

         }
     }
 }

3.5测试结果

很简单的例子，希望能看懂，这是基础。