如何：从剪贴板检索数据

项目
08/12/2011

Clipboard 类提供了可以用来与 Windows 操作系统剪贴板功能交互的方法。许多应用程序都将剪贴板用作一个临时数据储存库。例如，字处理器在剪切和粘贴操作期间使用剪贴板。剪贴板还可用来从一个应用程序向另一个应用程序传输信息。

某些应用程序可以在剪贴板上以多种格式存储数据，这样增加了可能使用该数据的其他应用程序的数量。剪贴板格式是一个用于标识格式的字符串。使用已标识格式的应用程序可以在剪贴板中检索关联的数据。 DataFormats 类提供了预定义的格式名称以方便您使用。您也可以使用您自己的格式名称，或使用某对象的类型作为其格式。有关向剪贴板添加数据的信息，请参见如何：将数据添加到剪贴板。

若要确定剪贴板是否包含特定格式的数据，请使用 Contains格式方法之一或 GetData 方法。若要从剪贴板检索数据，请使用 Get格式方法之一或 GetData 方法。这些方法是 .NET Framework 2.0 版中的新方法。

若要使用 .NET Framework 2.0 之前的版本访问剪贴板中的数据，请使用 GetDataObject 方法，并调用返回的 IDataObject 的方法。例如，若要确定某个特定格式在返回对象中是否可用，请调用 GetDataPresent 方法。

提示

所有基于 Windows 的应用程序都共享系统剪贴板。因此，当您切换到另一个应用程序时，其内容也会发生更改。

Clipboard 类只能在设置为单线程单元 (STA) 模式的线程中使用。若要使用此类，请确保您的 Main 方法已用 STAThreadAttribute 特性标记。

检索剪贴板中单一通用格式的数据

使用 GetAudioStream、GetFileDropList、GetImage 或 GetText 方法。还可以选择先使用相应的 Contains格式方法来确定数据在特定格式下是否可用。这些方法只在 .NET Framework 2.0 版中可用。

' Demonstrates SetAudio, ContainsAudio, and GetAudioStream.
Public Function SwapClipboardAudio( _
    ByVal replacementAudioStream As System.IO.Stream) _
    As System.IO.Stream

    Dim returnAudioStream As System.IO.Stream = Nothing

    If (Clipboard.ContainsAudio()) Then
        returnAudioStream = Clipboard.GetAudioStream()
        Clipboard.SetAudio(replacementAudioStream)
    End If

    Return returnAudioStream

End Function

' Demonstrates SetFileDropList, ContainsFileDroList, and GetFileDropList
Public Function SwapClipboardFileDropList(ByVal replacementList _
    As System.Collections.Specialized.StringCollection) _
    As System.Collections.Specialized.StringCollection

    Dim returnList As System.Collections.Specialized.StringCollection _
        = Nothing

    If Clipboard.ContainsFileDropList() Then

        returnList = Clipboard.GetFileDropList()
        Clipboard.SetFileDropList(replacementList)
    End If

    Return returnList

End Function

' Demonstrates SetImage, ContainsImage, and GetImage.
Public Function SwapClipboardImage( _
    ByVal replacementImage As System.Drawing.Image) _
    As System.Drawing.Image

    Dim returnImage As System.Drawing.Image = Nothing

    If Clipboard.ContainsImage() Then
        returnImage = Clipboard.GetImage()
        Clipboard.SetImage(replacementImage)
    End If

    Return returnImage
End Function

' Demonstrates SetText, ContainsText, and GetText.
Public Function SwapClipboardHtmlText( _
    ByVal replacementHtmlText As String) As String

    Dim returnHtmlText As String = Nothing

    If (Clipboard.ContainsText(TextDataFormat.Html)) Then
        returnHtmlText = Clipboard.GetText(TextDataFormat.Html)
        Clipboard.SetText(replacementHtmlText, TextDataFormat.Html)
    End If

    Return returnHtmlText

End Function

// Demonstrates SetAudio, ContainsAudio, and GetAudioStream.
public System.IO.Stream SwapClipboardAudio(
    System.IO.Stream replacementAudioStream)
{
    System.IO.Stream returnAudioStream = null;
    if (Clipboard.ContainsAudio())
    {
        returnAudioStream = Clipboard.GetAudioStream();
        Clipboard.SetAudio(replacementAudioStream);
    }
    return returnAudioStream;
}

// Demonstrates SetFileDropList, ContainsFileDroList, and GetFileDropList
public System.Collections.Specialized.StringCollection
    SwapClipboardFileDropList(
    System.Collections.Specialized.StringCollection replacementList)
{
    System.Collections.Specialized.StringCollection returnList = null;
    if (Clipboard.ContainsFileDropList())
    {
        returnList = Clipboard.GetFileDropList();
        Clipboard.SetFileDropList(replacementList);
    }
    return returnList;
}

// Demonstrates SetImage, ContainsImage, and GetImage.
public System.Drawing.Image SwapClipboardImage(
    System.Drawing.Image replacementImage)
{
    System.Drawing.Image returnImage = null;
    if (Clipboard.ContainsImage())
    {
        returnImage = Clipboard.GetImage();
        Clipboard.SetImage(replacementImage);
    }
    return returnImage;
}

// Demonstrates SetText, ContainsText, and GetText.
public String SwapClipboardHtmlText(String replacementHtmlText)
{
    String returnHtmlText = null;
    if (Clipboard.ContainsText(TextDataFormat.Html))
    {
        returnHtmlText = Clipboard.GetText(TextDataFormat.Html);
        Clipboard.SetText(replacementHtmlText, TextDataFormat.Html);
    }
    return returnHtmlText;
}

检索剪贴板中自定义格式的数据

使用具有自定义格式名称的 GetData 方法。此方法只在 .NET Framework 2.0 版中可用。

您还可以在使用 SetData 方法时使用预定义的格式名称。有关更多信息，请参见 DataFormats。

' Demonstrates SetData, ContainsData, and GetData
' using a custom format name and a business object.
Public ReadOnly Property TestCustomFormat() As Customer
    Get
        Clipboard.SetData("CustomerFormat", New Customer("Customer Name"))

        If Clipboard.ContainsData("CustomerFormat") Then
            Return CType(Clipboard.GetData("CustomerFormat"), Customer)
        End If

        Return Nothing
    End Get
End Property


...


<Serializable()> Public Class Customer

    Private nameValue As String = String.Empty

    Public Sub New(ByVal name As String)
        nameValue = name
    End Sub

    Public Property Name() As String
        Get
            Return nameValue
        End Get
        Set(ByVal value As String)
            nameValue = value
        End Set
    End Property

End Class

// Demonstrates SetData, ContainsData, and GetData
// using a custom format name and a business object.
public Customer TestCustomFormat
{
    get
    {
        Clipboard.SetData("CustomerFormat", new Customer("Customer Name"));
        if (Clipboard.ContainsData("CustomerFormat")) 
        {
            return Clipboard.GetData("CustomerFormat") as Customer;
        }
        return null;
    }
}


...


[Serializable]
public class Customer
{
    private string nameValue = string.Empty;
    public Customer(String name)
    {
        nameValue = name;
    }
    public string Name
    {
        get { return nameValue; }
        set { nameValue = value; }
    }
}

检索剪贴板中多种格式的数据

请使用 GetDataObject 方法。在 .NET Framework 2.0 的早期版本中，必须使用此方法才能检索剪贴板中的数据。

' Demonstrates how to use a DataObject to add
' data to the Clipboard in multiple formats.
Public Sub TestClipboardMultipleFormats()

    Dim data As New DataObject()

    ' Add a Customer object using the type as the format.
    data.SetData(New Customer("Customer as Customer object"))

    ' Add a ListViewItem object using a custom format name.
    data.SetData("CustomFormat", _
        New ListViewItem("Customer as ListViewItem"))

    Clipboard.SetDataObject(data)
    Dim retrievedData As DataObject = _
        CType(Clipboard.GetDataObject(), DataObject)

    If (retrievedData.GetDataPresent("CustomFormat")) Then

        Dim item As ListViewItem = _
            TryCast(retrievedData.GetData("CustomFormat"), ListViewItem)

        If item IsNot Nothing Then
            MessageBox.Show(item.Text)
        End If

    End If

    If retrievedData.GetDataPresent(GetType(Customer)) Then

        Dim customer As Customer = _
            CType(retrievedData.GetData(GetType(Customer)), Customer)

        If customer IsNot Nothing Then

            MessageBox.Show(customer.Name)
        End If

    End If

End Sub


...


<Serializable()> Public Class Customer

    Private nameValue As String = String.Empty

    Public Sub New(ByVal name As String)
        nameValue = name
    End Sub

    Public Property Name() As String
        Get
            Return nameValue
        End Get
        Set(ByVal value As String)
            nameValue = value
        End Set
    End Property

End Class

// Demonstrates how to use a DataObject to add
// data to the Clipboard in multiple formats.
public void TestClipboardMultipleFormats()
{
    DataObject data = new DataObject();

    // Add a Customer object using the type as the format.
    data.SetData(new Customer("Customer as Customer object"));

    // Add a ListViewItem object using a custom format name.
    data.SetData("CustomFormat", 
        new ListViewItem("Customer as ListViewItem"));

    Clipboard.SetDataObject(data);
    DataObject retrievedData = (DataObject)Clipboard.GetDataObject();

    if (retrievedData.GetDataPresent("CustomFormat"))
    {
        ListViewItem item = 
            retrievedData.GetData("CustomFormat") as ListViewItem;
        if (item != null)
        {
            MessageBox.Show(item.Text);
        }
    }

    if (retrievedData.GetDataPresent(typeof(Customer)))
    {
        Customer customer = 
            retrievedData.GetData(typeof(Customer)) as Customer;
        if (customer != null)
        {
            MessageBox.Show(customer.Name);
        }
    }
}


...


[Serializable]
public class Customer
{
    private string nameValue = string.Empty;
    public Customer(String name)
    {
        nameValue = name;
    }
    public string Name
    {
        get { return nameValue; }
        set { nameValue = value; }
    }
}

通过

如何：从剪贴板检索数据

检索剪贴板中单一通用格式的数据

检索剪贴板中自定义格式的数据

检索剪贴板中多种格式的数据

请参见

任务

其他资源

其他资源