C# 从 outlook 电子邮件中拖放附件

Question

我想在 WinForm 解决方案中使用/读取 Outlook 电子邮件中的附件。

例如:电子邮件附有 TXT 文件；我想将 TXT 文件拖放到 WinForm 中，同时读取 TXT。

Answer 1

这是一个老问题，但无论如何我都会提供另一个不涉及使用 Outlook 对象的答案。

This URL 提供了大约有 13 年历史但似乎仍然有效的工作代码，用于处理 Outlook 传递给 DropDrop 事件的“FileGroupDescriptor”和“FileContents”数据。以防万一链接失效，这里是相关代码，直接复制/粘贴:

拖动输入事件:

private void Form1_DragEnter(object sender, System.Windows.Forms.DragEventArgs e)
{
  // for this program, we allow a file to be dropped from Explorer
  if (e.Data.GetDataPresent(DataFormats.FileDrop))
  {  e.Effect = DragDropEffects.Copy;}
  //    or this tells us if it is an Outlook attachment drop
  else if (e.Data.GetDataPresent("FileGroupDescriptor"))
  {  e.Effect = DragDropEffects.Copy;}
  //    or none of the above
  else
  {  e.Effect = DragDropEffects.None;}
}

拖放事件:

private void Form1_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
{
  string [] fileNames = null;

  try
  {
    if ( e.Data.GetDataPresent(DataFormats.FileDrop,false) == true)
    {
      fileNames = (string []) e.Data.GetData(DataFormats.FileDrop);
      // handle each file passed as needed
      foreach( string fileName in fileNames)
      {
        // do what you are going to do with each filename
      }
    }
    else if (e.Data.GetDataPresent("FileGroupDescriptor"))
    {
      //
      // the first step here is to get the filename
      // of the attachment and
      // build a full-path name so we can store it
      // in the temporary folder
      //

      // set up to obtain the FileGroupDescriptor
      // and extract the file name
      Stream theStream = (Stream) e.Data.GetData("FileGroupDescriptor");
      byte [] fileGroupDescriptor = new byte[512];
      theStream.Read(fileGroupDescriptor,0,512);
      // used to build the filename from the FileGroupDescriptor block
      StringBuilder fileName = new StringBuilder("");
      // this trick gets the filename of the passed attached file
      for(int i=76; fileGroupDescriptor[i]!=0; i++)
      {  fileName.Append(Convert.ToChar(fileGroupDescriptor[i]));}
      theStream.Close();
      string path = Path.GetTempPath();
          // put the zip file into the temp directory
      string theFile = path+fileName.ToString();
          // create the full-path name

      //
      // Second step:  we have the file name.
      // Now we need to get the actual raw
      // data for the attached file and copy it to disk so we work on it.
      //

      // get the actual raw file into memory
      MemoryStream ms = (MemoryStream) e.Data.GetData(
          "FileContents",true);
      // allocate enough bytes to hold the raw data
      byte [] fileBytes = new byte[ms.Length];
      // set starting position at first byte and read in the raw data
      ms.Position = 0;
      ms.Read(fileBytes,0,(int)ms.Length);
      // create a file and save the raw zip file to it
      FileStream fs = new FileStream(theFile,FileMode.Create);
      fs.Write(fileBytes,0,(int)fileBytes.Length);

      fs.Close();  // close the file

      FileInfo tempFile = new FileInfo(theFile);

      // always good to make sure we actually created the file
      if ( tempFile.Exists == true)
      {
        // for now, just delete what we created
        tempFile.Delete();
      }
      else
      {  Trace.WriteLine("File was not created!");}
    }

  }
  catch (Exception ex)
  {
    Trace.WriteLine("Error in DragDrop function: " + ex.Message);

    // don't use MessageBox here - Outlook or Explorer is waiting !
  }

}

请注意，此代码没有Dispose 它应该处理的对象，例如MemoryStream 和FileStream 对象。