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";

        }
    }
}

   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;
           
        }

       
    }
}

  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);
        }
    }
}

  

   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。