Ajax怎么判断hint为空呀？

参数小于零的情况下

user 代码如下

UserServlet
public class UserservIet, extends HttpServlet
Jun ExPrivate static Final Jong serlaiversionito- 1892353777248894134-
aResource(name="idbc/sample")
1 Datasource(49; 7 mull
JABBC
protected void processRequest (HttpServletRequest request,
HttpServletResponse responsel
throws ServletException, I0Exception (
PrintWriter out
= response.getwriter();
System.out _print1n("doGet invoked!"F.
at
try {
String id = (String) request.getParameter("id");
Connection con
= ds. fetConnection
PreparedStatement D =
con.prepareStatement(
"SELECT * FROM tb) user WHERE id - @*);
ps.setString(1, id);