以ViewModel的方式绑定itemselect

public class ViewModel : INotifyPropertyChanged
{     
private Item _selectedItem;      
public ViewModel()     
{         
    Items = new ObservableCollection<Item>()             
    {                
      new Item {Name = "Foo"},                 
      new Item {Name = "Bar"}             
    };         
    foreach ( Item anItem in Items 
    {             
       anItem.PropertyChanged += OnItemIsSelectedChanged;         
    }     
}      
public ObservableCollection<Item> Items { get; private set; }      
public Item SelectedItem     
{        
 get { return _selectedItem; }        
 set { // only update if the value is difference, don't             
      // want to send false positives            
     if ( _selectedItem == value )             
    {                 
        return;             
    }             
                 
      _selectedItem = value;            
      OnPropertyChanged("SelectedItem");        
      }     
}      
public event PropertyChangedEventHandler PropertyChanged;     
protected void OnItemIsSelectedChanged(object sender, PropertyChangedEventArgs e)     
{         
         if ( e.PropertyName != "IsSelected" )         
         {             
              return;         
         }          
         SelectedItem = sender as Item;    
 }      
private void OnPropertyChanged(string propertyName)     
{         
     if ( PropertyChanged != null )         
    {             
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));         
    }    
 } 
}