例說INotifyPropertyChanged接口

  INotifyPropertyChanged 接口用於向客戶端(通常是執行綁定的客戶端)發出某一屬性值已更改的通知。

　　當綁定數據源的某屬性值改變時,它可以通知客戶端,並進行界面數據更新.而我們不用寫很多復雜的代碼來更新界面數據,這樣可以做到方法簡潔而清晰,INotifyPropertyChanged確實是一個強大的接口。

　　首先，我們需要了解如下有關Silverlight 2.0 數據綁定的術語:

　　Binding - 將綁定目標對象的屬性與數據源聯接起來

　　Source - 綁定的數據源

　　Mode - 綁定的數據流的方向 [System.Windows.Data.BindingMode枚舉]

　　BindingMode.OneTime - 一次綁定。創建綁定時一次性地更新綁定目標對象的屬性

　　BindingMode.OneWay - 單向綁定(默認值)。數據源的改變會自動通知到綁定目標對象的屬性

　　BindingMode.TwoWay - 雙向綁定。數據源或綁定目標對象的屬性的值發生改變時會互相通知。顯然，做數據驗證的話一定要是雙向綁定

　　INotifyPropertyChanged - 向客戶端發出某一屬性值已更改的通知

　　IValueConverter - 值轉換接口，將一個類型的值轉換為另一個類型的值。它提供了一種將自定義邏輯應用於綁定的方式

 

下面來實現INotifyPropertyChanged 接口的類

public  class User: INotifyPropertyChanged       // 類
    {
 
        private string _Name;
        public string Name
        {
            get { return this._Name; }
            set
            {
                this._Name = value;
                notifyPropertyChanged("Name");
            }
        }

        private bool sex;

        public bool Sex
        {
            get { return sex; }
            set
            {
                sex = value;
                notifyPropertyChanged("Sex");
            }
        }

        private int _Age;
        public int Age
        {
            get { return this._Age; }
            set
            {
                this._Age = value;
                notifyPropertyChanged("Age");
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;

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

     }

 

MainWindow.XAML:

 

<Window xmlns:my="clr-namespace:WpfApplication1"  x:Class="WpfApplication1.MainWindow"
        xmlns=" http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x=" http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525" >
   
<DockPanel  >
        <Grid  Height="300" Width="300" Background="#FFDE3030">
            <TextBlock Text="姓名：" Margin="42,38,130,237"  />
            <TextBox x:Name="tbName" Width="100" Height="30" Margin="107,35,93,235"  Text="{Binding Name, Mode=TwoWay}" />
            <TextBlock Text="年齡：" Margin="42,69,199,204" TextTrimming="None" />
            <TextBox x:Name="tbAge" Width="100" Height="30" Margin="107,66,93,204" Text="{Binding Age,Mode=TwoWay}"/>
            <CheckBox  x:Name="cbxSex" Content="性別" IsChecked="{Binding Sex,Mode=TwoWay}" Height="16" HorizontalAlignment="Left" Margin="224,35,0,0" VerticalAlignment="Top" Width="62" />
            
        </Grid>

    </DockPanel>
</Window>

     /// <summary>
    /// MainWindow.xaml 后台代碼    /// </summary>
    public partial class MainWindow : Window
    {
        User Myuser = new User();

        public MainWindow()
        {
            InitializeComponent();
            Myuser = new User();
            Myuser.Name = "劉李傑";
            Myuser.Age = 23;

            tbName.DataContext = Myuser;
            tbAge.DataContext = Myuser;
            cbxSex.DataContext = Myuser;
            Myuser.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(Myuser_PropertyChanged);

        }

        void Myuser_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            MessageBox.Show(e.PropertyName.ToString()+"改變");
        }