private void lendButton_Click(object sender, EventArgs e)//借阅,当图书可用时将图书的状态改为借阅 { if (yearComboBox.Text != "" && monthComboBox.Text != "" && dayComboBox.Text != "") { string year = yearComboBox.Text; string month = monthComboBox.Text; string day = dayComboBox.Text; BookShelfService.LendBook(currentBook, currentClient, year, month, day); } else { MessageBox.Show("没有输入正确的日期!", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information); } }