SharePoint：如何以编程方式将附件添加到列表项？

我有以下代码：

  SPList list = web.Lists[this.ListName];
  SPListItem item = list.Items.Add();

现在我想做的是：

   FileInfo[] attachments = attachmentDirectory.GetFiles();
        foreach (FileInfo attachment in attachments)
        {
           // Add the attachment from file system to the list item...

        }

如何将普通文件转换为字节数组？

 foreach (FileInfo attachment in attachments)
        {
            FileStream fs = new FileStream(attachment.FullName , FileMode.Open,FileAccess.Read);

            // Create a byte array of file stream length
            byte[] ImageData = new byte[fs.Length];

            //Read block of bytes from stream into the byte array
            fs.Read(ImageData,0,System.Convert.ToInt32(fs.Length));

            //Close the File Stream
            fs.Close();

            item.Attachments.Add(attachment.Name, ImageData); 


        }