//添加事件

　　　　private void AddRtb1Event()
        {
            rtb1.AllowDrop = true;
            
            rtb1.DragEnter += new DragEventHandler(rtb1_DragEnter);
            rtb1.DragDrop += new DragEventHandler(rtb1_DragDrop);
            
        }       
        private void rtb1_DragEnter(object sender, DragEventArgs e)
        {
            e.Effect = DragDropEffects.Copy  ;
            String[] supportedFormats = e.Data.GetFormats(true);
            if (supportedFormats != null)
            {
                List<string> sfList = new List<string>(supportedFormats);
                if (sfList.Contains(DataFormats.FileDrop.ToString()) )
                {
                    rtb1.EnableAutoDragDrop = false;
                }
                else
                {
                    rtb1.EnableAutoDragDrop = true;

                }
            }

            
        }

        private void rtb1_DragDrop(object sender, DragEventArgs e)
        {
            String[] supportedFormats = e.Data.GetFormats(true);
            if (supportedFormats != null)
            {
                List<string> sfList = new List<string>(supportedFormats);
                if (sfList.Contains(DataFormats.FileDrop.ToString()))
                {
                    string[] fileList = (string[])((System.Array)e.Data.GetData(DataFormats.FileDrop));
                    foreach (string fileName in fileList)
                    {
                        MessageBox.Show(fileName);
                    }
                }
            }
            rtb1.EnableAutoDragDrop = true;
        }

    }