HOW TO：使用 BindingSource 和 INotifyPropertyChanged 介面引發變更告知

發行項
08/21/2008

更新：2007 年 11 月

當資料來源中的型別實作 INotifyPropertyChanged 介面時，以及當屬性值變更而使該型別引發 PropertyChanged 事件時，BindingSource 元件會自動偵測資料來源中的變更。這項功能將會相當實用，因為繫結至 BindingSource 的控制項會因而在資料來源值發生變更時自動更新。

注意事項：
如果資料來源實作 INotifyPropertyChanged，而且您正在執行非同步作業，請不要在背景執行緒上對資料來源進行變更，而是應該在背景執行緒上讀取資料，然後在 UI 執行緒上將資料合併至清單中。

範例

下列程式碼範例將示範 INotifyPropertyChanged 介面的簡單實作。同時也會顯示 BindingSource 如何在 BindingSource 繫結至 INotifyPropertyChanged 型別清單時，自動將資料來源變更傳遞給繫結控制項。

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Data.Common
Imports System.Diagnostics
Imports System.Drawing
Imports System.Data.SqlClient
Imports System.Windows.Forms

' This form demonstrates using a BindingSource to bind
' a list to a DataGridView control. The list does not
' raise change notifications, however the DemoCustomer type 
' in the list does.

Public Class Form1
    Inherits System.Windows.Forms.Form
    ' This button causes the value of a list element to be changed.
    Private changeItemBtn As New Button()

    ' This is the DataGridView control that displays the contents 
    ' of the list.
    Private customersDataGridView As New DataGridView()

    ' This is the BindingSource used to bind the list to the 
    ' DataGridView control.
    Private customersBindingSource As New BindingSource()

    Public Sub New() 
        ' Set up the "Change Item" button.
        Me.changeItemBtn.Text = "Change Item"
        Me.changeItemBtn.Dock = DockStyle.Bottom
        AddHandler Me.changeItemBtn.Click, AddressOf changeItemBtn_Click
        Me.Controls.Add(Me.changeItemBtn)

        ' Set up the DataGridView.
        customersDataGridView.Dock = DockStyle.Top
        Me.Controls.Add(customersDataGridView)
        Me.Size = New Size(800, 200)
        AddHandler Me.Load, AddressOf Form1_Load

    End Sub 'New

    Private Sub Form1_Load(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Me.Load

        ' Create and populate the list of DemoCustomer objects
        ' which will supply data to the DataGridView.
        Dim customerList As New List(Of DemoCustomer)

        customerList.Add(DemoCustomer.CreateNewCustomer())
        customerList.Add(DemoCustomer.CreateNewCustomer())
        customerList.Add(DemoCustomer.CreateNewCustomer())

        ' Bind the list to the BindingSource.
        Me.customersBindingSource.DataSource = customerList

        ' Attach the BindingSource to the DataGridView.
        Me.customersDataGridView.DataSource = Me.customersBindingSource

    End Sub 'Form1_Load

    ' This event handler changes the value of the CompanyName
    ' property for the first item in the list.
    Private Sub changeItemBtn_Click(ByVal sender As Object, ByVal e As EventArgs) 
        ' Get a reference to the list from the BindingSource.
        Dim customerList As List(Of DemoCustomer) = _
            CType(customersBindingSource.DataSource, List(Of DemoCustomer))

        ' Change the value of the CompanyName property for the 
        ' first item in the list.
        customerList(0).CompanyName = "Tailspin Toys"

    End Sub



    <STAThread()>  _
    Shared Sub Main() 
        Application.EnableVisualStyles()
        Application.Run(New Form1())

    End Sub
End Class

' This class implements a simple customer type 
' that implements the IPropertyChange interface.

Public Class DemoCustomer
    Implements INotifyPropertyChanged
    ' These fields hold the values for the public properties.
    Private idValue As Guid = Guid.NewGuid()
    Private customerName As String = String.Empty
    Private companyNameValue As String = String.Empty
    Private phoneNumberValue As String = String.Empty

    Public Event PropertyChanged As PropertyChangedEventHandler _
        Implements INotifyPropertyChanged.PropertyChanged


    Private Sub NotifyPropertyChanged(ByVal info As String) 
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
    End Sub

    ' The constructor is private to enforce the factory pattern.
    Private Sub New() 
        customerName = "no data"
        companyNameValue = "no data"
        phoneNumberValue = "no data"

    End Sub


    ' This is the public factory method.
    Public Shared Function CreateNewCustomer() As DemoCustomer 
        Return New DemoCustomer()

    End Function

    ' This property represents an ID, suitable
    ' for use as a primary key in a database.
    Public ReadOnly Property ID() As Guid
        Get
            Return Me.idValue
        End Get
    End Property


    Public Property CompanyName() As String 
        Get
            Return Me.companyNameValue
        End Get

        Set(ByVal value As String)
            If Not (value = companyNameValue) Then
                Me.companyNameValue = value
                NotifyPropertyChanged("CompanyName")
            End If
        End Set
    End Property


    Public Property PhoneNumber() As String 
        Get
            Return Me.phoneNumberValue
        End Get

        Set(ByVal value As String)
            If Not (value = phoneNumberValue) Then
                Me.phoneNumberValue = value
                NotifyPropertyChanged("PhoneNumber")
            End If

        End Set
    End Property
End Class

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
using System.Drawing;
using System.Data.SqlClient;
using System.Windows.Forms;

// This form demonstrates using a BindingSource to bind
// a list to a DataGridView control. The list does not
// raise change notifications, however the DemoCustomer type 
// in the list does.
public class Form1 : System.Windows.Forms.Form
{
    // This button causes the value of a list element to be changed.
    private Button changeItemBtn = new Button();

    // This is the DataGridView control that displays the contents 
    // of the list.
    private DataGridView customersDataGridView = new DataGridView();

    // This is the BindingSource used to bind the list to the 
    // DataGridView control.
    private BindingSource customersBindingSource = new BindingSource();

    public Form1()
    {
        // Set up the "Change Item" button.
        this.changeItemBtn.Text = "Change Item";
        this.changeItemBtn.Dock = DockStyle.Bottom;
        this.changeItemBtn.Click +=
            new EventHandler(changeItemBtn_Click);
        this.Controls.Add(this.changeItemBtn);

        // Set up the DataGridView.
        customersDataGridView.Dock = DockStyle.Top;
        this.Controls.Add(customersDataGridView);
        this.Size = new Size(800, 200);
        this.Load += new EventHandler(Form1_Load);
    }

    private void Form1_Load(System.Object sender, System.EventArgs e)
    {
        // Create and populate the list of DemoCustomer objects
        // which will supply data to the DataGridView.
        List<DemoCustomer> customerList = new List<DemoCustomer>();
        customerList.Add(DemoCustomer.CreateNewCustomer());
        customerList.Add(DemoCustomer.CreateNewCustomer());
        customerList.Add(DemoCustomer.CreateNewCustomer());

        // Bind the list to the BindingSource.
        this.customersBindingSource.DataSource = customerList;

        // Attach the BindingSource to the DataGridView.
        this.customersDataGridView.DataSource =
            this.customersBindingSource;
    }

    // This event handler changes the value of the CompanyName
    // property for the first item in the list.
    void changeItemBtn_Click(object sender, EventArgs e)
    {
        // Get a reference to the list from the BindingSource.
        List<DemoCustomer> customerList =
            this.customersBindingSource.DataSource as List<DemoCustomer>;

        // Change the value of the CompanyName property for the 
        // first item in the list.
        customerList[0].CompanyName = "Tailspin Toys";

    }

    

    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.Run(new Form1());
    }
}

// This class implements a simple customer type 
// that implements the IPropertyChange interface.
public class DemoCustomer : INotifyPropertyChanged
{
    // These fields hold the values for the public properties.
    private Guid idValue = Guid.NewGuid();
    private string customerName = String.Empty;
    private string companyNameValue = String.Empty;
    private string phoneNumberValue = String.Empty;

    public event PropertyChangedEventHandler PropertyChanged;
    
    private void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }

    // The constructor is private to enforce the factory pattern.
    private DemoCustomer()
    {
        customerName = "no data";
        companyNameValue = "no data";
        phoneNumberValue = "no data";
    }

    // This is the public factory method.
    public static DemoCustomer CreateNewCustomer()
    {
        return new DemoCustomer();
    }

    // This property represents an ID, suitable
    // for use as a primary key in a database.
    public Guid ID
    {
        get
        {
            return this.idValue;
        }
    }

    public string CompanyName
    {
        get
        {
            return this.companyNameValue;
        }

        set
        {
            if (value != this.companyNameValue)
            {
                this.companyNameValue = value;
                NotifyPropertyChanged("CompanyName");
            }
        }
    }

    public string PhoneNumber
    {
        get
        {
            return this.phoneNumberValue;
        }

        set
        {
            if (value != this.phoneNumberValue)
            {
                this.phoneNumberValue = value;
                NotifyPropertyChanged("PhoneNumber");
            }
        }
    }
}

編譯程式碼

這個範例需要：

System、System.Data、System.Drawing 和 System.Windows.Forms 組件的參考。

如需從 Visual Basic 或 Visual C# 的命令列建置這個範例的詳細資訊，請參閱從命令列建置 (Visual Basic) 或使用 csc.exe 建置命令列。您也可以透過將程式碼貼入新的專案，在 Visual Studio 中建置此範例。

請參閱

共用方式為

HOW TO：使用 BindingSource 和 INotifyPropertyChanged 介面引發變更告知

範例

編譯程式碼

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參考

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