如何：实现属性更改通知
更新：2007 年 11 月
若要支持 OneWay 或 TwoWay 绑定，从而使绑定目标属性能够自动反映绑定源的动态更改（例如，用户编辑窗体后，预览窗格会自动更新），类需要提供相应的属性更改通知。此示例介绍了如何创建实现 INotifyPropertyChanged 的类。
示例
若要实现 INotifyPropertyChanged，需要声明 PropertyChanged 事件并创建 OnPropertyChanged 方法。然后，对于每个需要更改通知的属性，只要进行了更新，就可以调用 OnPropertyChanged。
Imports System.ComponentModel
' This class implements INotifyPropertyChanged
' to support one-way and two-way bindings
' (such that the UI element updates when the source
' has been changed dynamically)
Public Class Person
Implements INotifyPropertyChanged
Private personName As String
Sub New()
End Sub
Sub New(ByVal Name As String)
Me.personName = Name
End Sub
' Declare the event
Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Public Property Name() As String
Get
Return personName
End Get
Set(ByVal value As String)
personName = value
' Call OnPropertyChanged whenever the property is updated
OnPropertyChanged("Name")
End Set
End Property
' Create the OnPropertyChanged method to raise the event
Protected Sub OnPropertyChanged(ByVal name As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
End Sub
End Class
using System.ComponentModel;
namespace SDKSample
{
// This class implements INotifyPropertyChanged
// to support one-way and two-way bindings
// (such that the UI element updates when the source
// has been changed dynamically)
public class Person : INotifyPropertyChanged
{
private string name;
// Declare the event
public event PropertyChangedEventHandler PropertyChanged;
public Person()
{
}
public Person(string value)
{
this.name = value;
}
public string PersonName
{
get { return name; }
set
{
name = value;
// Call OnPropertyChanged whenever the property is updated
OnPropertyChanged("PersonName");
}
}
// Create the OnPropertyChanged method to raise the event
protected void OnPropertyChanged(string name)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(name));
}
}
}
}
有关 Person 类如何可用于支持 TwoWay 绑定的示例，请参见如何：控制文本框文本更新源的时间。
有关完整示例，请参见简单绑定示例。