UC知道if rs.next
来源：百度知道 编辑：UC知道 时间：2024/06/02 14:29:47
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._
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._
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也不是空来着。你的con如果是Connection的话就创建个Statement或PreparedStatement对象。最好把封装的代码也发下。
把ResultSet rs=con.executeQuery(sql);改成上面两句试过了没啊？
空指针异常