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problem using my user defined class in my JSP page

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LMachado1@gmail.com - 18 Apr 2005 04:24 GMT
I tried to define a class and use it in my JSP page, but i'm running
into some problems...

here is the JSP code:
=============================================================
<%@ page
       import = "java.io.*, java.lang.*, java.sql.*, bkwrmspackage.*"
%>

<jsp:useBean id="user" class="bkwrmspackage.UserData" scope="session"/>
<jsp:setProperty name="user" property="*"/>

<HTML>
<HEAD><TITLE>BookWorms - Authenticating...</TITLE></HEAD>
<BODY>

<%
       DbClass dbinstance;
       int status = 0;
       status = dbinstance.verifyUser(user.getUsername(),
user.getUpassword());

       if(status == 1){
               out.println("you have logged in successfully\n");
       }else if(status == -1){
               out.println("login info invalid\n");
       }else if(status == -2){
               out.println("there was an unknown error during login,
try again\n");

       }
%>

here is the code for the class:
=============================================================
package bkwrmspackage;

import  java.sql.*;
import java.lang.*;
import java.io.*;

public class DbClass {

   public int verifyUser(String username, String password) {
       Connection dbconn;
       PreparedStatement sql;

       try{//try to load the mysql driver
           Class.forName("org.gjt.mm.mysql.Driver");
           try{
               //establish a connection to the database

dbconn=DriverManager.getConnection("jdbc:mysql://localhost/group10","group10","pass");

               Statement statement = dbconn.createStatement();
               String query = "SELECT * FROM members WHERE username =
" + username;
               ResultSet rs;
               rs = statement.executeQuery(query);

               while(rs.next()){
                   String dpass = rs.getString("upassword");

                   if(dpass.equals(password)){
                       return 1;
                   }
                   return -1;
               }

           }

           catch (SQLException s){
               return -2;
           }
       }
        catch (ClassNotFoundException err){
           return -2;
       }
       return -2;
   }
}

here is the error message:
=============================================================
type Exception report

message

description The server encountered an internal error () that prevented
it from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to compile class for JSP

An error occurred at line: 11 in the jsp file: /group10/auth.jsp

Generated servlet error:
   [javac] Since fork is true, ignoring compiler setting.
   [javac] Compiling 1 source file
   [javac] Since fork is true, ignoring compiler setting.
   [javac]
/usr/jakarta-tomcat-4.1.24/work/Standalone/localhost/_/group10/auth_jsp.java:73:
variable dbinstance might not have been initialized
   [javac]     status = dbinstance.verifyUser(user.getUsername(),
user.getUpassword());
   [javac]                  ^
   [javac] 1 error

    at
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:130)
    at
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:293)
    at
org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:353)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:370)
    at
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:473)
    at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:190)
    at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
    at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
    at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
    at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
    at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
    at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
    at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:594)
    at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
    at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
    at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
    at java.lang.Thread.run(Thread.java:536)

I'm not sure why i keep getting this error. I've even tried changing:
"DbClass dbinstance;" to "DbClass dbinstance = new DbClass();" and I
get the following error:
============================================================
type Exception report

message

description The server encountered an internal error () that prevented
it from fulfilling this request.

exception

org.apache.jasper.JasperException
    at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:254)
    at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
    at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
    at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
    at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
    at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
    at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
    at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:594)
    at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
    at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
    at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
    at java.lang.Thread.run(Thread.java:536)

root cause

javax.servlet.ServletException
    at
org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:536)
    at org.apache.jsp.auth_jsp._jspService(auth_jsp.java:100)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
    at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)
    at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
    at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
    at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
    at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
    at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
    at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
    at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
    at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
    at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
    at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
    at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:594)
    at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
    at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
    at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
    at java.lang.Thread.run(Thread.java:536)

i have NO IDEA what this error is trying to tell me...can anyone help?

Thanks in advance,
--Lucas
Reply to this Message
SMC - 18 Apr 2005 05:19 GMT
On Mon, 18 Apr 2005 13:24:33 +1000, LMachado1 wrote:

> I tried to define a class and use it in my JSP page, but i'm running
> into some problems...
[quoted text clipped - 15 lines]
>         status = dbinstance.verifyUser(user.getUsername(),
> user.getUpassword());

You declare dbinstance (of type DbClass) but you don't create an instance
of it before calling the verifyUser() method.

You need:

DbClass dbinstance = new DbClass();

Or else you can make your verifyUser method static, in which case you
could just do

status = DbClass.verifyUser(user.getUsername());

Signature

Sean

Reply to this Message
LMachado1@gmail.com - 18 Apr 2005 15:17 GMT
> I'm not sure why i keep getting this error. I've even tried changing:
> "DbClass dbinstance;" to "DbClass dbinstance = new DbClass();" and I
[quoted text clipped - 11 lines]
> org.apache.jasper.JasperException
>     at

org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:254)
>     at

org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
>     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
>     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
>     at

org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
>     at

org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
>     at

org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
>     at

org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
>     at

org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
>     at

org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:594)
>     at

org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
>     at

org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
>     at

org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
>     at java.lang.Thread.run(Thread.java:536)
>
> root cause
>
> javax.servlet.ServletException
>     at

org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:536)
>     at org.apache.jsp.auth_jsp._jspService(auth_jsp.java:100)
>     at
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
>     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
>     at

org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:210)
>     at

org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
>     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
>     at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
>     at

org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
>     at

org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
>     at

org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
>     at

org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
>     at

org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
>     at

org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
>     at

org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
>     at
> org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
>     at

org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
>     at

org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:594)
>     at

org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:392)
>     at

org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
>     at

org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:619)
>     at java.lang.Thread.run(Thread.java:536)
>
> i have NO IDEA what this error is trying to tell me...can anyone help?
>
> Thanks in advance,
> --Lucas

sorry, there is so much stuff in my post  you may have missed that
part... I've tried making it static, and that works, but I'd rather not
make it a static function if I can help it...

--Lucas
Reply to this Message


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