浅尝MVVMLight…

    最近要写WPF技术的项目,所以要学习一下关于WPF的知识…今天呢了解了一下MVVM的知识,具体内容如下了…

    MVVM呢是Model-View-ViewModel的缩写了…MVVM的由来算是有MVP(Model-View-Presenter)模式与WPF的结合新型架构框架了,它立足于原有MVP框架并且把WPF的新特性揉合进去，以应对客户日益复杂的需求变化…

    MVVMLight呢算是MVVM他是MVVM的一种实现,当然还有其他的其它的实现了(例如微软的Prism),但现在MVVMLight是一个公认的比较好的一种实现了…

    下面介绍一下MVVMLight的安装方法了…

    我比较喜欢从Visual Studio中的NuGet Package中来获取MVVMLight了,如果想安装MVVMLight Toolkit请自行度娘或谷姐…

    首先呢从Visaul Studio中的工具菜单项打开 扩展管理器,然后再搜索栏中输入 NuGet Package进行搜索…

   

    然后安装NuGet Package,如果已经安装过的可以直接跳过进行下一步了…NuGet Package不是必须安装的了,也可以直接安装MVVMLight了,但是安装了NuGet Package以后,它可以使你的MVVMLight保持到最新版本了,当有更新的时候呢会自动有更新提示了…推荐使用了…

    安装完NuGet Package后,然后再在 解决方案 右键选择 管理NuGet程序包 中搜索MVVMLight进行安装…至此MVMMLight就安装完成了…以后如果那个项目需要使用MVVMLight库就只要在 管理NuGet程序包中进行一次MVVMLight安装就可以了…

   

    下面写段代码使用一下MVVMLight了…

     建立项目MVVMLightTest…然后在项目中添加类Song,类中代码如下…

   1:  /// <summary>

   2:      /// Model of a 'song'.

   3:      /// </summary>

   4:      public class Song

   5:      {

   6:          #region Members

   7:          string _artistName;

   8:          string _songTitle;

   9:          #endregion

  10:   

  11:          #region Properties

  12:          /// <summary>

  13:          /// The artist name.

  14:          /// </summary>

  15:          public string ArtistName

  16:          {

  17:              get { return _artistName; }

  18:              set { _artistName = value; }

  19:          }

  20:   

  21:          /// <summary>

  22:          /// The song title.

  23:          /// </summary>

  24:          public string SongTitle

  25:          {

  26:              get { return _songTitle; }

  27:              set { _songTitle = value; }

  28:          }

  29:          #endregion

  30:      }

         然后再添加类SongViewModel,类中代码如下…

        

     1:      /// <summary>

     2:      /// This class is a view model of a song.

     3:      /// </summary>

     4:      public class SongViewModel:ObservableObject

     5:      {

     6:          #region Construction

     7:          /// <summary>

     8:          /// Constructs the default instance of a SongViewModel

     9:          /// </summary>

     10:          public SongViewModel()

     11:          {

     12:              _song = new Song { ArtistName = "Unknown", SongTitle = "Unknown" };

     13:          }

     14:          #endregion

     15:   

     16:          #region Members

     17:          Song _song;

     18:          int _count = 0;

     19:          #endregion

     20:   

     21:          #region Properties

     22:          public Song Song

     23:          {

     24:              get

     25:              {

     26:                  return _song;

     27:              }

     28:              set

     29:              {

     30:                  _song = value;

     31:              }

     32:          }

     33:   

     34:          public string ArtistName

     35:          {

     36:              get { return Song.ArtistName; }

     37:              set

     38:              {

     39:                  if (Song.ArtistName != value)

     40:                  {

     41:                      this.Song.ArtistName = value;

     42:                      RaisePropertyChanged("ArtistName");

     43:                  }

     44:              }

     45:          } 

     46:          #endregion

     47:   

     48:          #region Commands

     49:          void UpdateArtistNameExexute()

     50:          {

     51:              ++_count;

     52:              ArtistName = string.Format("Elvis ({0})", _count);

     53:          }

     54:          bool CanUpdateArtistNameExecute()

     55:          {

     56:              return true;

     57:          }

     58:          public ICommand UpdateArtistName

     59:          {

     60:              get

     61:              {

     62:                  return new RelayCommand(UpdateArtistNameExexute, CanUpdateArtistNameExecute);

     63:              }

     64:          }

     65:          #endregion

     66:      }

    然后再MainWindow.xaml中添加以下代码…

       1:   <Window.DataContext>

       2:          <!-- Declaratively create an instance of our SongViewModel -->

       3:          <local:SongViewModel />

       4:      </Window.DataContext>

       5:      <Grid>

       6:          <Grid.RowDefinitions>

       7:              <RowDefinition Height="Auto" />

       8:              <RowDefinition Height="Auto" />

       9:              <RowDefinition Height="Auto" />

     10:          </Grid.RowDefinitions>

     11:          <Grid.ColumnDefinitions>

     12:              <ColumnDefinition Width="Auto" />

     13:              <ColumnDefinition Width="Auto" />

     14:          </Grid.ColumnDefinitions>

     15:          <Label Grid.Column="0" Grid.Row="0" Content="Example 1 - this doesn't work!" />

     16:          <Label Grid.Column="0" Grid.Row="1" Content="Artist:  " />

     17:          <Label Grid.Column="1" Grid.Row="1" Content="{Binding ArtistName, Mode=TwoWay}" />

     18:          <Button Grid.Column="1" Grid.Row="2" Name="ButtonUpdateArtist" Content="Update Artist Name" Command="{Binding UpdateArtistName}"/>

      19:      </Grid>

    然后生成并运行程序…效果如下

   

    此程序虽然功能狠狠简单,但是它却体现出了MVVM的思想…程序中的所有业务逻辑放在了ViewModel中,在MainWindow的.cs文件中未添加任何代码…只需在MainWindow.xaml中进行数据和命令的绑定即可…