如何：从剪贴板检索数据

项目
05/04/2023

Clipboard 类提供可用于与 Windows 操作系统剪贴板功能交互的方法。许多应用程序使用剪贴板作为数据的临时存储库。例如，文字处理器在剪切和粘贴操作期间使用剪贴板。剪贴板还可用于将信息从一个应用程序传输到另一个应用程序。

某些应用程序以多种格式将数据存储在剪贴板上，以增加可能使用该数据的其他应用程序的数量。剪贴板格式是标识格式的字符串。使用所标识格式的应用程序可以检索剪贴板上的关联数据。 DataFormats 类提供预定义的格式名称供你使用。还可以使用自己的格式名称或使用对象的类型作为其格式。有关将数据添加到剪贴板的信息，请参阅如何：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，请使用一种 ContainsFormat 方法或 GetData 方法。若要从剪贴板检索数据，请使用一种 GetFormat 方法或 GetData 方法。这些方法是 .NET Framework 2.0 中的新增方法。

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 Clipboard.GetDataObject 方法并调用返回的 IDataObject 的方法。例如，若要确定特定格式是否在返回的对象中可用，请调用 GetDataPresent 方法。

注意

所有基于 Windows 的应用程序都使用系统剪贴板。因此，切换到另一个应用程序时，内容可能会更改。

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，请确保使用 Main 特性标记 STAThreadAttribute 方法。

以一种通用格式从剪贴板检索数据

使用 GetAudioStream、GetFileDropList、GetImage 或 GetText 方法。（可选）首先使用相应的 ContainsFormat 方法来确定数据是否以特定格式提供。这些方法仅在 .NET Framework 2.0 中可用。

// 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;
}

' 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

以自定义格式从剪贴板检索数据

以自定义格式名称使用 GetData 方法。此方法仅在 .NET Framework 2.0 中可用。

还可以将预定义的格式名称用于 SetData 方法。有关详细信息，请参阅 DataFormats。

// 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;
    }
}

' 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 string nameValue = string.Empty;
    public Customer(String name)
    {
        nameValue = name;
    }
    public string Name
    {
        get { return nameValue; }
        set { nameValue = value; }
    }
}

<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

以多种格式从剪贴板检索数据

使用 GetDataObject 方法。对于 .NET Framework 2.0 之前的版本，必须使用此方法从剪贴板中检索数据。

// 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);
        }
    }
}

' 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 string nameValue = string.Empty;
    public Customer(String name)
    {
        nameValue = name;
    }
    public string Name
    {
        get { return nameValue; }
        set { nameValue = value; }
    }
}

<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

如何：从剪贴板检索数据

以一种通用格式从剪贴板检索数据

以自定义格式从剪贴板检索数据

以多种格式从剪贴板检索数据

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