INotifyPropertyChanged 接口

INotifyPropertyChanged 接口

用于向客户端(通常是执行绑定的客户端)发出某一属性值已更改的通知。

例如,考虑一个带有名为 FirstName 属性的 Person 对象。若要提供一般性属性更改通知,则 Person 类型实现 INotifyPropertyChanged 接口并在 FirstName 更改时引发 PropertyChanged 事件。

若要在将客户端与数据源进行绑定时发出更改通知,则绑定类型应具有下列任一功能:

  • 实现 INotifyPropertyChanged 接口(首选)。
  • 为绑定类型的每个属性提供更改事件。

上述这两个功能不要同时实现。

示例

下面的代码示例演示如何实现 INotifyPropertyChanged 接口。在运行此示例时,您将注意到绑定的 DataGridView 控件无需重置绑定即能反映数据源中的更改。如果使用 CallerMemberName 属性,对 NotifyPropertyChanged 方法不必指定属性名称作为字符串参数。有关详细信息,请参阅Caller Information (C# and Visual Basic)

  1 using System;
  2 using System.Collections.Generic;
  3 using System.ComponentModel;
  4 using System.Drawing;
  5 using System.Runtime.CompilerServices;
  6 using System.Windows.Forms;
  7 
  8 // Change the namespace to the project name.
  9 namespace TestNotifyPropertyChangedCS
 10 {
 11     // This form demonstrates using a BindingSource to bind
 12     // a list to a DataGridView control. The list does not
 13     // raise change notifications. However the DemoCustomer type 
 14     // in the list does.
 15     public partial class Form1 : Form
 16     {
 17         // This button causes the value of a list element to be changed.
 18         private Button changeItemBtn = new Button();
 19 
 20         // This DataGridView control displays the contents of the list.
 21         private DataGridView customersDataGridView = new DataGridView();
 22 
 23         // This BindingSource binds the list to the DataGridView control.
 24         private BindingSource customersBindingSource = new BindingSource();
 25 
 26         public Form1()
 27         {
 28             InitializeComponent();
 29 
 30             // Set up the "Change Item" button.
 31             this.changeItemBtn.Text = "Change Item";
 32             this.changeItemBtn.Dock = DockStyle.Bottom;
 33             this.changeItemBtn.Click +=
 34                 new EventHandler(changeItemBtn_Click);
 35             this.Controls.Add(this.changeItemBtn);
 36 
 37             // Set up the DataGridView.
 38             customersDataGridView.Dock = DockStyle.Top;
 39             this.Controls.Add(customersDataGridView);
 40 
 41             this.Size = new Size(400, 200);
 42         }
 43 
 44         private void Form1_Load(object sender, EventArgs e)
 45         {
 46             // Create and populate the list of DemoCustomer objects
 47             // which will supply data to the DataGridView.
 48             BindingList<DemoCustomer> customerList = new BindingList<DemoCustomer>();
 49             customerList.Add(DemoCustomer.CreateNewCustomer());
 50             customerList.Add(DemoCustomer.CreateNewCustomer());
 51             customerList.Add(DemoCustomer.CreateNewCustomer());
 52 
 53             // Bind the list to the BindingSource.
 54             this.customersBindingSource.DataSource = customerList;
 55 
 56             // Attach the BindingSource to the DataGridView.
 57             this.customersDataGridView.DataSource =
 58                 this.customersBindingSource;
 59 
 60         }
 61 
 62         // Change the value of the CompanyName property for the first 
 63         // item in the list when the "Change Item" button is clicked.
 64         void changeItemBtn_Click(object sender, EventArgs e)
 65         {
 66             // Get a reference to the list from the BindingSource.
 67             BindingList<DemoCustomer> customerList =
 68                 this.customersBindingSource.DataSource as BindingList<DemoCustomer>;
 69 
 70             // Change the value of the CompanyName property for the 
 71             // first item in the list.
 72             customerList[0].CustomerName = "Tailspin Toys";
 73             customerList[0].PhoneNumber = "(708)555-0150";
 74         }
 75 
 76     }
 77 
 78     // This is a simple customer class that 
 79     // implements the IPropertyChange interface.
 80     public class DemoCustomer : INotifyPropertyChanged
 81     {
 82         // These fields hold the values for the public properties.
 83         private Guid idValue = Guid.NewGuid();
 84         private string customerNameValue = String.Empty;
 85         private string phoneNumberValue = String.Empty;
 86 
 87         public event PropertyChangedEventHandler PropertyChanged;
 88 
 89         // This method is called by the Set accessor of each property.
 90         // The CallerMemberName attribute that is applied to the optional propertyName
 91         // parameter causes the property name of the caller to be substituted as an argument.
 92         private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
 93         {
 94             if (PropertyChanged != null)
 95             {
 96                 PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
 97             }
 98         }
 99 
100         // The constructor is private to enforce the factory pattern.
101         private DemoCustomer()
102         {
103             customerNameValue = "Customer";
104             phoneNumberValue = "(312)555-0100";
105         }
106 
107         // This is the public factory method.
108         public static DemoCustomer CreateNewCustomer()
109         {
110             return new DemoCustomer();
111         }
112 
113         // This property represents an ID, suitable
114         // for use as a primary key in a database.
115         public Guid ID
116         {
117             get
118             {
119                 return this.idValue;
120             }
121         }
122 
123         public string CustomerName
124         {
125             get
126             {
127                 return this.customerNameValue;
128             }
129 
130             set
131             {
132                 if (value != this.customerNameValue)
133                 {
134                     this.customerNameValue = value;
135                     NotifyPropertyChanged();
136                 }
137             }
138         }
139 
140         public string PhoneNumber
141         {
142             get
143             {
144                 return this.phoneNumberValue;
145             }
146 
147             set
148             {
149                 if (value != this.phoneNumberValue)
150                 {
151                     this.phoneNumberValue = value;
152                     NotifyPropertyChanged();
153                 }
154             }
155         }
156     }
157 }

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