private void frmModify_Load(object sender, EventArgs e)
        {
            InsertColumn();
            
            this.KeyUp += new System.Windows.Forms.KeyEventHandler(this.frmModify_KeyUp);
            this.KeyPreview = true; //窗体接收所有键事件

            if (Scanner_Open())
            {
                thread = new Thread(ScannerRd);
                thread.IsBackground = true;
                thread.Start();
                timer1.Enabled = true;
            }
            else
            {
                MessageBox.Show("扫描失败");
            }
            

        }

 private void frmModify_KeyUp(object sender, KeyEventArgs e)
        {
            j++;
            //MessageBox.Show(e.KeyValue.ToString());
            switch (e.KeyValue)
            { 
                case 27:
                    //if (dt.Rows.Count > 0)
                    //    dt.Rows.RemoveAt(dt.Rows.Count - 1);
                    int i = dt.Rows.Count;
                    if (i > 0)
                        dt.Rows.RemoveAt(i - 1);
                    break;
                case 37:
                case 39:
                    Scanner_Trig();
                    timer1.Enabled = false;
                    break;

                default: break;
            }
            

        }