如何：使用 SaveFileDialog 组件保存文件

项目
08/18/2008

更新：2007 年 11 月

用户可以使用 SaveFileDialog 组件浏览文件系统并选择要保存的文件。该对话框返回用户在对话框中选定的文件的路径和名称。不过，您必须编写代码才能真正地将文件写入磁盘。

使用 SaveFileDialog 组件保存文件

显示“保存文件”对话框并调用一个方法保存用户选定的文件。

使用 SaveFileDialog 组件的 OpenFile 方法保存文件。此方法提供了一个可以写入的 Stream 对象。

下面的示例使用 DialogResult 属性获取文件的名称，并使用 OpenFile 方法保存文件。OpenFile 方法提供了可以写入文件的流。

在下面的示例中，有一个分配了图像的 Button 控件。单击该按钮时，将使用一个允许 .gif、.jpeg 和 .bmp 类型文件的筛选器实例化 SaveFileDialog 组件。如果在“保存文件”对话框中选定了此类型的文件，那么将保存按钮的图像。

安全说明：
若要获取或设置 FileName 属性，程序集需要具有由 System.Security.Permissions.FileIOPermission 类授予的特权级别。如果在部分信任的上下文中运行，则该进程可能会因特权不足而引发一个异常。有关更多信息，请参见代码访问安全性基础知识。

该示例假设窗体上有一个 Button 控件，该控件的 Image 属性设置为 .gif、.jpeg 或 .bmp 类型的文件。

说明：
FileDialog 类的 FilterIndex 属性（根据继承的特性，该属性属于 SaveFileDialog 类）使用从 1 开始的索引。如果您通过编写代码以特定格式保存数据（例如，以纯文本而不是二进制格式保存文件），那么这一点很重要。以下示例介绍了该属性。

Private Sub Button2_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button2.Click
   ' Displays a SaveFileDialog so the user can save the Image
   ' assigned to Button2.
   Dim saveFileDialog1 As New SaveFileDialog()
   saveFileDialog1.Filter = "JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif"
   saveFileDialog1.Title = "Save an Image File"
   saveFileDialog1.ShowDialog()

   ' If the file name is not an empty string open it for saving.
   If saveFileDialog1.FileName <> "" Then
      ' Saves the Image via a FileStream created by the OpenFile method.
      Dim fs As System.IO.FileStream = Ctype _
         (saveFileDialog1.OpenFile(), System.IO.FileStream)
      ' Saves the Image in the appropriate ImageFormat based upon the
      ' file type selected in the dialog box.
      ' NOTE that the FilterIndex property is one-based.
      Select Case saveFileDialog1.FilterIndex
         Case 1
            Me.button2.Image.Save(fs, _
               System.Drawing.Imaging.ImageFormat.Jpeg)

         Case 2
            Me.button2.Image.Save(fs, _
               System.Drawing.Imaging.ImageFormat.Bmp)

         Case 3
            Me.button2.Image.Save(fs, _
               System.Drawing.Imaging.ImageFormat.Gif)
       End Select

       fs.Close()
    End If
End Sub

private void button2_Click(object sender, System.EventArgs e)
{
   // Displays a SaveFileDialog so the user can save the Image
   // assigned to Button2.
   SaveFileDialog saveFileDialog1 = new SaveFileDialog();
   saveFileDialog1.Filter = "JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif";
   saveFileDialog1.Title = "Save an Image File";
   saveFileDialog1.ShowDialog();

   // If the file name is not an empty string open it for saving.
   if(saveFileDialog1.FileName != "")
   {
      // Saves the Image via a FileStream created by the OpenFile method.
      System.IO.FileStream fs = 
         (System.IO.FileStream)saveFileDialog1.OpenFile();
      // Saves the Image in the appropriate ImageFormat based upon the
      // File type selected in the dialog box.
      // NOTE that the FilterIndex property is one-based.
      switch(saveFileDialog1.FilterIndex)
      {
         case 1 : 
         this.button2.Image.Save(fs, 
            System.Drawing.Imaging.ImageFormat.Jpeg);
         break;

         case 2 : 
         this.button2.Image.Save(fs, 
            System.Drawing.Imaging.ImageFormat.Bmp);
         break;

         case 3 : 
         this.button2.Image.Save(fs, 
            System.Drawing.Imaging.ImageFormat.Gif);
         break;
      }

   fs.Close();
   }
}

private void button2_Click(Object sender, System.EventArgs e)
{
   // Displays a SaveFileDialog so the user can save the Image
   // assigned to Button2.
   SaveFileDialog saveFileDialog1 = new SaveFileDialog();
   saveFileDialog1.set_Filter("JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif");
   saveFileDialog1.set_Title("Save an Image File");
   saveFileDialog1.ShowDialog();

   // If the file name is not an empty string open it for saving.
   if (saveFileDialog1.get_FileName() != "")
   {
      // Saves the Image via a FileStream created by the OpenFile method.
      System.IO.FileStream fs =
         (System.IO.FileStream)saveFileDialog1.OpenFile();
      // Saves the Image in the appropriate ImageFormat based upon the
      // File type selected in the dialog box.
      // NOTE that the FilterIndex property is one-based.
      switch (saveFileDialog1.get_FilterIndex())
      {
         case 1:
            this.button2.get_Image().Save(fs,
               System.Drawing.Imaging.ImageFormat.get_Jpeg());
            break;

         case 2:
            this.button2.get_Image().Save(fs,
               System.Drawing.Imaging.ImageFormat.get_Bmp());
            break;

         case 3:
            this.button2.get_Image().Save(fs,
               System.Drawing.Imaging.ImageFormat.get_Gif());
            break;
      }

      fs.Close();
   }
}

private:
   System::Void button2_Click(System::Object ^ sender,
      System::EventArgs ^ e)
   {
      // Displays a SaveFileDialog so the user can save the Image
      // assigned to Button2.
      SaveFileDialog ^ saveFileDialog1 = new SaveFileDialog();
      saveFileDialog1->Filter = 
         "JPeg Image|*.jpg|Bitmap Image|*.bmp|Gif Image|*.gif";
      saveFileDialog1->Title = "Save an Image File";
      saveFileDialog1->ShowDialog();
      // If the file name is not an empty string, open it for saving.
      if(saveFileDialog1->FileName != "")
      {
         // Saves the Image through a FileStream created by
         // the OpenFile method.
         System::IO::FileStream ^ fs = 
            safe_cast<System::IO::FileStream*>(
            saveFileDialog1->OpenFile());
         // Saves the Image in the appropriate ImageFormat based on
         // the file type selected in the dialog box.
         // Note that the FilterIndex property is one based.
         switch(saveFileDialog1->FilterIndex)
         {
            case 1 :
               this->button2->Image->Save(fs,
                  System::Drawing::Imaging::ImageFormat::Jpeg);
               break;
            case 2 :
               this->button2->Image->Save(fs, 
                  System::Drawing::Imaging::ImageFormat::Bmp);
               break;
            case 3 :
               this->button2->Image->Save(fs, 
                  System::Drawing::Imaging::ImageFormat::Gif);
               break;
         }
      fs->Close();
      }
   }

(（Visual C#、Visual J# 和 Visual C++）在窗体的构造函数中放置以下代码，以注册事件处理程序。

this.button2.Click += new System.EventHandler(this.button2_Click);

this.button2.add_Click(new System.EventHandler(this.button2_Click));

this->button2->Click += gcnew
   System::EventHandler(this, &Form1::button2_Click);

有关编写文件流的更多信息，请参见 FileStream.BeginWrite 方法和 FileStream.Write 方法。

说明：
某些控件，如 RichTextBox 控件，具有保存文件的能力。有关更多信息，请参见 MSDN 联机库技术文章 Essential Code for Windows Forms Dialog Boxes（Windows 窗体对话框的基本代码）的“SaveFileDialog Component”（SaveFileDialog 组件）部分。

通过

如何：使用 SaveFileDialog 组件保存文件

使用 SaveFileDialog 组件保存文件

请参见

参考

其他资源

其他资源