FileDialog.Filter 屬性

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

取得或設定目前的檔名篩選字串，以決定出現在對話方塊中 [另存檔案類型] 或 [檔案類型] 方塊的選項。

public:
 property System::String ^ Filter { System::String ^ get(); void set(System::String ^ value); };

public string Filter { get; set; }

member this.Filter : string with get, set

Public Property Filter As String

屬性值

String

在對話方塊中可以使用檔案篩選選項。

例外狀況

ArgumentException

Filter 格式是無效的。

範例

下列程式碼範例會 OpenFileDialog 使用 的 實作 FileDialog ，並說明如何建立、設定屬性，以及顯示對話方塊。 此範例會使用 Filter 和 FilterIndex 屬性來提供使用者的篩選清單。 此範例需要放置於它的 表單 Button ，以及 System.IO 新增至它的命名空間。

private:
   void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      Stream^ myStream;
      OpenFileDialog^ openFileDialog1 = gcnew OpenFileDialog;

      openFileDialog1->InitialDirectory = "c:\\";
      openFileDialog1->Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
      openFileDialog1->FilterIndex = 2;
      openFileDialog1->RestoreDirectory = true;

      if ( openFileDialog1->ShowDialog() == System::Windows::Forms::DialogResult::OK )
      {
         if ( (myStream = openFileDialog1->OpenFile()) != nullptr )
         {
            // Insert code to read the stream here.
            myStream->Close();
         }
      }
   }

var fileContent = string.Empty;
var filePath = string.Empty;

using (OpenFileDialog openFileDialog = new OpenFileDialog())
{
    openFileDialog.InitialDirectory = "c:\\";
    openFileDialog.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
    openFileDialog.FilterIndex = 2;
    openFileDialog.RestoreDirectory = true;

    if (openFileDialog.ShowDialog() == DialogResult.OK)
    {
        //Get the path of specified file
        filePath = openFileDialog.FileName;

        //Read the contents of the file into a stream
        var fileStream = openFileDialog.OpenFile();

        using (StreamReader reader = new StreamReader(fileStream))
        {
            fileContent = reader.ReadToEnd();
        }
    }
}

MessageBox.Show(fileContent, "File Content at path: " + filePath, MessageBoxButtons.OK);

Private Sub button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim myStream As Stream = Nothing
    Dim openFileDialog1 As New OpenFileDialog()

    openFileDialog1.InitialDirectory = "c:\"
    openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"
    openFileDialog1.FilterIndex = 2
    openFileDialog1.RestoreDirectory = True

    If openFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
        Try
            myStream = openFileDialog1.OpenFile()
            If (myStream IsNot Nothing) Then
                ' Insert code to read the stream here.
            End If
        Catch Ex As Exception
            MessageBox.Show("Cannot read file from disk. Original error: " & Ex.Message)
        Finally
            ' Check this again, since we need to make sure we didn't throw an exception on open.
            If (myStream IsNot Nothing) Then
                myStream.Close()
            End If
        End Try
    End If
End Sub

備註

針對每個篩選選項，篩選字串包含篩選的描述，後面接著垂直線 (|) 和篩選模式。 不同篩選選項的字串會以垂直線分隔。

以下是篩選字串的範例：

Text files (*.txt)|*.txt|All files (*.*)|*.*

您可以將數個篩選模式新增至篩選，方法是將檔案類型與分號分隔，例如：

Image Files(*.BMP;*.JPG;*.GIF)|*.BMP;*.JPG;*.GIF|All files (*.*)|*.*

FilterIndex使用 屬性來設定先向使用者顯示哪一個篩選選項。

另請參閱

• CheckFileExists
• FilterIndex