if rs.next

题目

if rs.next
org.apache.jasper.JasperException:An exception occurred processing JSP page /admin/Acheck.jsp at line 16
13:
14:String sql="select * from cqut_admin where Id=+login+ and Password=+password+";
15:ResultSet rs=con.executeQuery(sql);
16:if(rs.next()){
17:session.setAttribute("login",login);
18:response.sendRedirect("index.htm");
19:}else{
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:515)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:426)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause
java.lang.NullPointerException
org.apache.jsp.admin.Acheck_jsp._jspService(Acheck_jsp.java:70)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.htt

答案

是不是需要用con创建个Statement或PreparedStatement对象,再用这个对象执行executeQuery? Statement stat = con.createStatement(); ResultSet rs = stat.executeQuery(sql); 记得即使没取到数据rs也不是...