validar na classe a existência de uma variável de sessão

[Carlos Rocha]

Alguém pode me ajudar?

A idéia aqui é validar na classe a existência de uma variável de sessão criada em um servlet

Meu jsp

<%@ page import="java.util.*" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<jsp:useBean id="validaAdmin" class="dao.admin.TestaLoginAdmin" />
<c:set var="admin" value="${validaAdmin.testaLogin(request)}" />
<c:set var="redireciona" value="${validaAdmin.redireciona(request)}" />

<c:choose>
<c:when test="${admin != null}">          
            ${admin.nome};
   </c:when>
<c:otherwise>
            ${redireciona};
   </c:otherwise>
</c:choose>

Minha classe

 
package dao.admin;

import model.Admin;

import java.io.*;  
import javax.servlet.*;  
import javax.servlet.http.*;

public class TestaLoginAdmin 
{ 
public Admin testaLogin(HttpServletRequest request) throws ServletException, IOException 
{
HttpSession sessao = request.getSession();

Admin admin = (Admin) sessao.getAttribute("admin");

if(admin != null)
{
return admin;
}
return null;
}

public void redireciona(HttpServletResponse response) throws ServletException, IOException
{
response.sendRedirect("index.jsp");
}
}

Erro:

 
HTTP Status 500 - org.apache.jasper.JasperException: An exception occurred processing JSP page /_global/testaAdmin.jsp at line 5


type Exception report

message org.apache.jasper.JasperException: An exception occurred processing JSP page /_global/testaAdmin.jsp at line 5

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

exception
org.apache.jasper.JasperException: org.apache.jasper.JasperException: An exception occurred processing JSP page /_global/testaAdmin.jsp at line 5

2: <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
3: 
4: <jsp:useBean id="validaAdmin" class="dao.admin.TestaLoginAdmin" />
5: <c:set var="admin" value="${validaAdmin.testaLogin(request)}" />
6: <c:set var="redireciona" value="${validaAdmin.redireciona(request)}" />
7: 
8: <c:choose>


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:555)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:461)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


root cause
org.apache.jasper.JasperException: An exception occurred processing JSP page /_global/testaAdmin.jsp at line 5

2: <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
3: 
4: <jsp:useBean id="validaAdmin" class="dao.admin.TestaLoginAdmin" />
5: <c:set var="admin" value="${validaAdmin.testaLogin(request)}" />
6: <c:set var="redireciona" value="${validaAdmin.redireciona(request)}" />
7: 
8: <c:choose>


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:574)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:476)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:934)
org.apache.jsp.admin.principal_jsp._jspService(principal_jsp.java:89)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


root cause
org.apache.jasper.el.JspELException: /_global/testaAdmin.jsp(5,0) '${validaAdmin.testaLogin(request)}' java.lang.NullPointerException
org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:123)
org.apache.jsp._005fglobal.testaAdmin_jsp._jspx_meth_c_005fset_005f0(testaAdmin_jsp.java:161)
org.apache.jsp._005fglobal.testaAdmin_jsp._jspService(testaAdmin_jsp.java:121)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:934)
org.apache.jsp.admin.principal_jsp._jspService(principal_jsp.java:89)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


root cause
java.lang.NullPointerException
dao.admin.TestaLoginAdmin.testaLogin(TestaLoginAdmin.java:13)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
javax.el.BeanELResolver.invoke(BeanELResolver.java:165)
org.apache.jasper.el.JasperELResolver.invoke(JasperELResolver.java:147)
org.apache.el.parser.AstValue.getValue(AstValue.java:159)
org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:115)
org.apache.jsp._005fglobal.testaAdmin_jsp._jspx_meth_c_005fset_005f0(testaAdmin_jsp.java:161)
org.apache.jsp._005fglobal.testaAdmin_jsp._jspService(testaAdmin_jsp.java:121)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:934)
org.apache.jsp.admin.principal_jsp._jspService(principal_jsp.java:89)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)


note The full stack trace of the root cause is available in the Apache Tomcat/8.0.22 logs.


Apache Tomcat/8.0.22

Alguém pode me ajudar?

Edited July 19, 2015 at 12:53 AM by carcleo

[Rui Carlos]

Penso que podes começar por verificar se a variável request não tem o valor null. Se for null, o método deverá parar logo por aí.

[Carlos Rocha]

O que esta pegando é que não estou conseguindo fazer essa linha funcionar!

<c:set var="admin" value="${validaAdmin.testaLogin(request)}" />

o parâmetro "request" passado á função "testaLogin", não esta devidamente informado.

Não sei como fazer para que o request chegue à classe!

O erro esta exatamente ali!

[Carlos Rocha]

Pessoal, ainda não consegui resolver essa!

Alguém pode me ajudar?