Silverlight MVVM模式开发 -MVVMLight

silverlight的mvvm模式框架有，MVVM Light:http://mvvmlight.codeplex.com

Caliburn:http://caliburn.codeplex.com/

Prism:http://compositewpf.codeplex.com/

其中MVVMLight是一个轻量级框架，大家可以参考。下面重点说一下View与Command的原理及使用。

大家可以参照源代码：

1.每一个ViewModel都继承ViewModelBase类：大致的源代码是：

using System;
using System.ComponentModel;
using System.Linq.Expressions;

namespace TAMS.Common
{
    /// <summary>
    /// INotifyPropertyChanged的基类
    /// </summary>
    public class PropertyChangedBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void NotifyPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

    /// <summary>
    /// PropertyChangedBase的扩展方法
    /// </summary>
    public static class PropertyChangedBaseEx
    {
        public static void NotifyPropertyChanged<T, TProperty>(this T propertyChangedBase, Expression<Func<T, TProperty>> expression) where T : PropertyChangedBase
        {
            var memberExpression = expression.Body as MemberExpression;
            if (memberExpression != null)
            {
                string propertyName = memberExpression.Member.Name;
                propertyChangedBase.NotifyPropertyChanged(propertyName);
            }
            else
                throw new NotImplementedException();
        }
    }
}

2. Command类的核心：

using System;
using System.Windows.Input;

namespace TAMS.Common
{
    /// <summary>        
    /// 功能描述：Silverlight 命令 代理类
    /// 创 建 者：kntao
    /// 创建日期：2011/6/29
    /// 修改记录：            
    /// </summary>
    public class DelegateCommand : ICommand
    {
        /// <summary>
        /// Occurs when changes occur that affect whether the command should execute.
        /// </summary>
        public event EventHandler CanExecuteChanged;

        Func<object, bool> canExecute;
        Action<object> executeAction;
        bool canExecuteCache;

        /// <summary>
        /// Initializes a new instance of the <see cref="DelegateCommand"/> class.
        /// </summary>
        /// <param name="executeAction">The execute action.</param>
        /// <param name="canExecute">The can execute.</param>
        public DelegateCommand(Action<object> executeAction,Func<object, bool> canExecute)
        {
            this.executeAction = executeAction;
            this.canExecute = canExecute;
        }

        #region ICommand Members
        /// <summary>
        /// Defines the method that determines whether the command 
        /// can execute in its current state.
        /// </summary>
        /// <param name="parameter">
        /// Data used by the command. 
        /// If the command does not require data to be passed,
        /// this object can be set to null.
        /// </param>
        /// <returns>
        /// true if this command can be executed; otherwise, false.
        /// </returns>
        public bool CanExecute(object parameter)
        {
            bool tempCanExecute = canExecute(parameter);

            if (canExecuteCache != tempCanExecute)
            {
                canExecuteCache = tempCanExecute;
                if (CanExecuteChanged != null)
                {
                    CanExecuteChanged(this, new EventArgs());
                }
            }

            return canExecuteCache;
        }

        /// <summary>
        /// Defines the method to be called when the command is invoked.
        /// </summary>
        /// <param name="parameter">
        /// Data used by the command. 
        /// If the command does not require data to be passed, 
        /// this object can be set to null.
        /// </param>
        public void Execute(object parameter)
        {
            executeAction(parameter);
        }
        #endregion
    }
}

3. 一个简单的运用：显示图书的列表，并可以通过图书内容进行搜索：

XAML文件：

<UserControl
             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:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk" x:Class="MvvmLight1.MainPage"
             mc:Ignorable="d"
             Height="800"
             Width="1024"
             >

    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Skins/MainSkin.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>

	<UserControl.DataContext>
		<Binding Path="Main" Source="{StaticResource Locator}"/>
	</UserControl.DataContext>

    <Grid x:Name="LayoutRoot">

        <TextBlock FontSize="36"
                   FontWeight="Bold"
                   Foreground="Purple"
                   Text="{Binding Welcome}"
                   VerticalAlignment="Center"
                   HorizontalAlignment="Center"
                   TextWrapping="Wrap" />
        <TextBox x:Name="textBox" HorizontalAlignment="Left" Margin="32,24,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="201" />
        <Button Content="搜索" Margin="0,24,645,0" VerticalAlignment="Top" HorizontalAlignment="Right" Width="83" Command="{Binding SearchCommand, Mode=OneWay}" CommandParameter="{Binding Text, ElementName=textBox}" />

        <sdk:DataGrid  Margin="32,72,168,328" AutoGenerateColumns="False" ItemsSource="{Binding BookSource}" Height="400">
    		<sdk:DataGrid.Columns>
                <sdk:DataGridTextColumn Binding="{Binding BookIdBookId}" Header="图书编号"/>
                <sdk:DataGridTextColumn Binding="{Binding BookName}" Header="图书名称"/>
                <sdk:DataGridTextColumn Binding="{Binding BookAuthor}" Header="图书作者"/>
    		</sdk:DataGrid.Columns>
    	</sdk:DataGrid>

    </Grid>
</UserControl>

大家可以通过Blend界面设置绑定属性，

Silverlight MVVM模式开发 -MVVMLight

Silverlight MVVM模式开发 -MVVMLight
2. ViewModel

using System.Collections.Generic;
using GalaSoft.MvvmLight;
using System.Windows.Input;
using GalaSoft.MvvmLight.Command;
using System.Linq;

namespace MvvmLight1.ViewModel
{
    /// <summary>
    /// This class contains properties that the main View can data bind to.
    /// <para>
    /// Use the <strong>mvvminpc</strong> snippet to add bindable properties to this ViewModel.
    /// </para>
    /// <para>
    /// You can also use Blend to data bind with the tool's support.
    /// </para>
    /// <para>
    /// See http://www.galasoft.ch/mvvm/getstarted
    /// </para>
    /// </summary>
    public class MainViewModel : ViewModelBase
    {
        private IList<BookInfo> _bookSource;

        #region 绑定属性

        public IList<BookInfo> BookSource
        {
            get { return _bookSource; }
            set
            {
                if(_bookSource != value)
                {
                    _bookSource = value;
                    RaisePropertyChanged("BookSource");
                }
            }
        }

        #endregion
        /// <summary>
        /// Initializes a new instance of the MainViewModel class.
        /// </summary>
        public MainViewModel()
        {
            if (IsInDesignMode)
            {
                // Code runs in Blend --> create design time data.
            }
            else
            {
                // Code runs "for real"
                BookSource = GetBooks();
                SearchCommand = new RelayCommand<string>(
                    (bookTitle) =>
                        {
                            BookSource = GetBooks().Where(b => b.BookName.Contains(bookTitle)).ToList<BookInfo>();
                        }
                    );
            }
        }

        ////public override void Cleanup()
        ////{
        ////    // Clean up if needed

        ////    base.Cleanup();
        ////}

	
		#region Commands

        public ICommand SearchCommand { get; private set; }
			
		#endregion

        #region Data Source

        public class BookInfo
        {
            public int BookId { get; set; }
            public string BookName { get; set; }
            public string BookAuthor { get; set; }
        }


        public IList<BookInfo> GetBooks()
        {
            return new List<BookInfo>
                       {
                           new BookInfo() {BookId = 1, BookName = "CLR via C#（第3版）微软技术丛书", BookAuthor = "Richter"},
                           new BookInfo() {BookId = 2, BookName = "Windows Phone Mango开发实践", BookAuthor = "高雪松"},
                           new BookInfo() {BookId = 3, BookName = "C#本质论(第3版)", BookAuthor = "米凯利斯"},
                           new BookInfo() {BookId = 4, BookName = "ASP.NET本质论", BookAuthor = "郝冠军"},
                           new BookInfo() {BookId = 5, BookName = "Microsoft .NET企业级应用架构设计", BookAuthor = "埃斯波西托"},
                           new BookInfo() {BookId = 6, BookName = "你必须知道的.NET（第2版）", BookAuthor = "王涛"},
                           new BookInfo() {BookId = 7, BookName = "ASP.NET 4从入门到精通（微软技术丛书）", BookAuthor = "谢菲尔徳"},
                           new BookInfo() {BookId = 8, BookName = "ADO.NET 2.0技术内幕", BookAuthor = "斯塞帕（Sceppa，D.）"},
                           new BookInfo() {BookId = 9, BookName = "NET组件程序设计（第2版）", BookAuthor = "洛威（Lowy，J.）"},
                           new BookInfo(){BookId = 9, BookName = "庖丁解牛：纵向切入ASP.NET 3.5控件和组件开发技术（第2版）", BookAuthor = "郑健"}
                       };
        }
        #endregion
    }
}

代码下载：http://download.csdn.net/download/kntao/3730030