private void textBox9_TextChanged_1(object sender, EventArgs e) { String circuBookNo = textBox9.Text; textBox11.Text = ""; textBox10.Text = ""; label7.Text = ""; label7.ForeColor = Color.Red; bookBorrowAble = false; checkBorrowAble(); if (circuBookNo.Length == 10) { try { CircuBookClass book = BookInfo.queryABookInfo(circuBookNo); textBox11.Text = book.BookName; textBox10.Text = book.PublishingHouse; } catch (System.ArgumentOutOfRangeException) { label7.Text = "图书标识号有误!"; return; } if (!AS.BookBorrowAble(textBox9.Text)) { label7.Text = "书籍已被借出!"; } else { label7.ForeColor = Color.Green; label7.Text = "该书籍可借阅"; bookBorrowAble = true; checkBorrowAble(); } } }