FileDialog.Filter 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取或设置当前文件名筛选器字符串，该字符串决定对话框的“另存为文件类型”或“文件类型”框中出现的选择内容。

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

属性值

String

对话框中可用的文件筛选选项。

例外

ArgumentException

Filter 格式无效。

示例

下面的代码示例使用 OpenFileDialog 和 的 FileDialog 实现，说明了如何创建、设置属性以及显示对话框。 该示例使用 Filter 和 FilterIndex 属性为用户提供筛选器列表。 该示例需要一个窗体，其中放置了 一个 Button ，并 System.IO 添加了命名空间。

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

注解

对于每个筛选选项，筛选器字符串包含筛选器的说明，后跟垂直条 (|) 和筛选器模式。 不同筛选选项的字符串由竖线分隔。

下面是筛选器字符串的示例：

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

可以通过用分号分隔文件类型来向筛选器添加多个筛选器模式，例如：

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

FilterIndex使用 属性设置首先向用户显示的筛选选项。

另请参阅

• CheckFileExists
• FilterIndex