//a 文本框
private void txtTSPName_Enter(object sender, EventArgs e)
        {
            if (txtTSPName.Text.Trim() != string.Empty && txtTrayCode.Text.Trim() != string.Empty )
            {
                MessageBox.Show("不能更改承运商编码", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                if (txtGoodCode.Text == string.Empty) txtGoodCode.Focus();
                if(txtWeight.Text==string.Empty)txtWeight.Focus();
                
            }
        }

 private void txtTSPName_Leave(object sender, EventArgs e)
        {
                txtTrayCode.Focus();
        }

//b文本框
 private void txtTrayCode_Enter(object sender, EventArgs e)
        {
           
            if (txtTSPName.Text.Trim() == string.Empty)
            {
                MessageBox.Show("请先输入承运商编码", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                txtTSPName.Focus();
            }
            else if (txtTSPName.Text.Trim() != string.Empty && txtTrayCode.Text.Trim() != string.Empty && txtGoodCode.Text.Trim() != string.Empty)
            {
                MessageBox.Show("不能更改托盘号", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                if (txtGoodCode.Text == string.Empty) txtGoodCode.Focus();
                if (txtWeight.Text == string.Empty) txtWeight.Focus();//txtWeight是d文本框
            }
        }



 private void txtTrayCode_Leave(object sender, EventArgs e)
        {
            if (txtTSPName.Text == string.Empty)
            {
                txtTSPName.Focus();
            }
            else
            {
                txtGoodCode.Focus();
            }
        }

//c 文本框
private void txtGoodCode_Enter(object sender, EventArgs e)
        {
            if (txtTSPName.Text.Trim() == string.Empty)
            {
                MessageBox.Show("请先输入承运商编码", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                txtTSPName.Focus();
            }
            else
                if (txtTrayCode.Text.Trim() == string.Empty)
                {
                    MessageBox.Show("请先扫描托盘号", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    txtTrayCode.Focus();
                }
        }

  private void txtGoodCode_Leave(object sender, EventArgs e)
        {
            txtWeight.Focus();
        }