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MVVM(Model View ViewModel)是由MVC和MVP模式发展来的一种模式，它主要目的就是将应用程序的代码和界面分离开，这样界面开发可以更专注于设计界面，也使得UI界面更容易变换和测试，下面来看一下这3层的主要功能
1.Model层
数据访问层，一般定义为一个或多个类，以面向对象的方式将数据表示出来。
2.View层
表示层，UI界面的实现以及通过Binding和Command来实现与ViewModel层的交互
3.ViewModel层
负责View和Model之间的信息转换，将View的Command传到Model，以及通过Binding来实现与和View层的数据传递。
下面是一个MVVM模式的数据绑定实例：
思路：
1.定义一个实体类（Model层）来保存数据。
2.创建ViewModel层：声明一个集合类（ObservableCollection<T>）来作为绑定的数据源，且ViewModel层必须是实现了INotifyPropertyChanged接口，这样在数据源发生变化时才能及时通知Binding来更改目标值（View层中）的变化。
3.创建View层。如果要绑定ViewModel层中的数据，必须将ViewModel层中的命名空间引用，然后添加到Resource中，并设置一个key（本实例中设置为“food”）,然后将Resource中的资源赋值给Grid控件中的DataContent属性，则在Grid中就可以使用ViewModel层中的数据源了。
Food.cs代码如下（Model层）
namespace BindingDataDemo.Model { public class Food { public string Name { get; set; } public string Description { get; set; } public string IconUri { get; set; } public string Type { get; set; } } }
FoodViewModel.cs代码如下（ViewModel层）
using System; using System.ComponentModel; using BindingDataDemo.Model; using System.Collections.ObjectModel; namespace BindingDataDemo.ViewModel { public class FoodViewModel : INotifyPropertyChanged { private ObservableCollection<Food> _allFood; public ObservableCollection<Food> AllFood { get { if (_allFood == null) _allFood = new ObservableCollection<Food>(); return _allFood; } set { if (_allFood != value) { _allFood = value; NotifyPropertyChanged("AllFood"); } } } public FoodViewModel() { try { Food item0 = new Food() { Name = "西红柿", IconUri = "Images/Tomato.png", Type = "Healthy" ,Description="西红柿的味道不错。" }; Food item1 = new Food() { Name = "茄子", IconUri = "Images/Beer.png", Type = "NotDetermined", Description = "不知道这个是否好吃。" }; Food item2 = new Food() { Name = "火腿", IconUri = "Images/fries.png", Type = "Unhealthy", Description = "这是不健康的食品。" }; Food item3 = new Food() { Name = "三明治", IconUri = "Images/Hamburger.png", Type = "Unhealthy" ,Description="肯德基的好吃？" }; Food item4 = new Food() { Name = "冰激凌", IconUri = "Images/icecream.png", Type = "Healthy", Description = "给小朋友吃的。" }; Food item5 = new Food() { Name = "Pizza", IconUri = "Images/Pizza.png", Type = "Unhealthy" ,Description="这个非常不错。" }; Food item6 = new Food() { Name = "辣椒", IconUri = "Images/Pepper.png", Type = "Healthy", Description = "我不喜欢吃这东西。" }; AllFood.Add(item0); AllFood.Add(item1); AllFood.Add(item2); AllFood.Add(item3); AllFood.Add(item4); AllFood.Add(item5); AllFood.Add(item6); } catch ( Exception e ) { System.Windows.MessageBox.Show( "Exception: " + e.Message ); } } // 定义PropertyChanged 事件 public event PropertyChangedEventHandler PropertyChanged; public void NotifyPropertyChanged(string propertyName) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } } }
MainPage.xaml代码如下（View层）
<phone:PhoneApplicationPage x:Class="BindingDataDemo.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone" xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:my="clr-namespace:BindingDataDemo.ViewModel" mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768" FontFamily="{StaticResource PhoneFontFamilyNormal}" FontSize="{StaticResource PhoneFontSizeNormal}" Foreground="{StaticResource PhoneForegroundBrush}" SupportedOrientations="Portrait" Orientation="Portrait" shell:SystemTray.IsVisible="True"> <phone:PhoneApplicationPage.Resources> <my:FoodViewModel x:Key="food" /> </phone:PhoneApplicationPage.Resources> <Grid x:Name="LayoutRoot" Background="Transparent"> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28"> <TextBlock x:Name="ApplicationTitle" Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}"/> <TextBlock x:Name="PageTitle" Text="数据绑定" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/> </StackPanel> <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0" DataContext="{StaticResource food }"> <ListBox x:Name="listBox" HorizontalContentAlignment="Stretch" ItemsSource="{Binding AllFood}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal" Background="Gray" Width="450" Margin="10"> <Image Source="{Binding IconUri}" Stretch="None"/> <TextBlock Text="{Binding Name}" FontSize="40" Width="150"/> <TextBlock Text="{Binding Description}" FontSize="20" Width="280"/> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Grid> </Grid> </phone:PhoneApplicationPage>
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原文地址：http://www.cnblogs.com/runninglzw/p/4420215.html
