Error 404 directed/or not to the Servlet. Problems with Layout

Question

I am studying java for web (EE) and would like to know if you could help solve a java problem!

I have in my web.xml a call to the erro404.jsp file that is at the root of the site to filter out pages that do not exist!

It turns out that if the missing page called is at the root as well, for example /site/paginaInexiste.jsp, it will be at the same level as erro404.jsp and when erro404.jsp is called, all its internal links (css, includes[code]) will work.

However, when the Missing Page is inside any root folder, that is, outside the level of error404.jsp, example /site/pasta/paginaInexistente.jsp, so erro404.jsp is called normally but its internal links don’t work.

I tried sending 404 errors to a Servlet RequestDispatcher to call erro404.jsp because both Servlet and erro404.jsp are at the same level, but it didn’t work!

web xml.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>imwsaogotardo</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>AdminServlet</servlet-name>
    <servlet-class>imwsaogotardo.src.controller.AdminServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>AdminServlet</servlet-name>
    <url-pattern>/imwsaogotardo/AdminServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>ProfessorServlet</servlet-name>
    <servlet-class>imwsaogotardo.src.controller.ProfessorServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ProfessorServlet</servlet-name>
    <url-pattern>/imwsaogotardo/ProfessorServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>SalaServlet</servlet-name>
    <servlet-class>imwsaogotardo.src.controller.SalaServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SalaServlet</servlet-name>
    <url-pattern>/imwsaogotardo/SalaServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>UsuarioServlet</servlet-name>
    <servlet-class>imwsaogotardo.src.controller.UsuarioServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>UsuarioServlet</servlet-name>
    <url-pattern>/imwsaogotardo/UsuarioServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <servlet-name>PerguntaServlet</servlet-name>
    <servlet-class>imwsaogotardo.src.dao.pergunta.PerguntaServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>PerguntaServlet</servlet-name>
    <url-pattern>/imwsaogotardo/PerguntaServlet</url-pattern>
  </servlet-mapping>

  <error-page>
    <error-code>404</error-code>
    <location>/ErrosServlet</location>
  </error-page>
  <error-page>
    <error-code>500</error-code>
    <location>/ErrosServlet</location>
  </error-page>
</web-app>

And in Servlet

package erros;

import java.io.IOException;


import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(
            name="ErrosServlet", 
            urlPatterns={"/ErrosServlet"}
           )
public class ErrosServlet extends HttpServlet 
{
    private static final long serialVersionUID = 1L;

    public ErrosServlet()
    {
        super();
    }

    public void doPost(HttpServletRequest req, HttpServletResponse res)    throws ServletException, IOException
    {
        Throwable throwable = (Throwable) req.getAttribute("javax.servlet.error.exception");
        Integer statusCode = (Integer) req.getAttribute("javax.servlet.error.status_code");

        req.setAttribute("errorType", throwable);
        req.setAttribute("statusCode", statusCode);

        //colocando o setStatus OK
        res.setStatus(HttpServletResponse.SC_OK);

        // We have to remove the exception from the request. If we do not remove the IE9 will not display out error page.
        // IE9 will think that some error created a crash inside our application if we do not remove the exception from the request.
        req.setAttribute("javax.servlet.error.exception", null);
        req.setAttribute("javax.servlet.error.status_code", null);

        RequestDispatcher requestDispatcher = null;

        if(statusCode==404)
        {
            requestDispatcher = req.getRequestDispatcher("/erro404.jsp");
        }
        else if(statusCode==500)
        {
            requestDispatcher = req.getRequestDispatcher("/erro500.jsp");
        }

        requestDispatcher.forward(req, res);    

    }

    public void doGet(HttpServletRequest req, HttpServletResponse res)    throws ServletException, IOException
    {
        doPost(req, res);
    }   
}

Note: I did not launch Servet on web.xml

Is there any other resource?

Adding the error page:

<jsp:useBean id="constantes" class="util.Constantes" />     
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>    
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link type="text/css" rel="stylesheet" href="_global/_css/estiloSite.css" />
<title>${constantes.tituloSite}</title>
</head>
<body class="fadeIn">

 <div id="topo"> <jsp:include page="_global/topoErro.jsp" /> </div>
 <div id="meio"> <jsp:include page="erro404Conteudo.jsp" /> </div>
 <div id="mapa"> <jsp:include page="_global/mapaErro.jsp" /> </div>
 <div id="creditos"> <jsp:include page="_global/creditosErro.jsp" /> </div>

 </body>
</html>

Next erro404Conteudo.jsp

<div id="central">

        Esta página não existe! <br/>
        Código do Erro : ${statusCode} <br/>
        <img src="_img/editar.png">
        <a href="_global/topoErro.jsp">Editar</a>
        <jsp:include page="_global/topoErro.jsp" />

</div>

Good, remembering that Dispatcher is done naturally. The error is due only to the style and image links. Hrefs and includes usually occur!

Answer 1

I don’t know how your project is going and what I suggest is a way to solve, not necessarily the most elegant.

Since you have not posted your page with the links that are not working, I assume that you OR are using fixed paths OR relative paths, always starting with current path, which in certain cases will give error.

How to solve? You should always consider the context of your application when composing the links, in order to always have the complete link to your resource, making the reference to be direct to the resource and not reporting, in the same folder, etc. To do this you can do it in various ways, like these:

• JSTL: If you are using JSTL you can do something like this:

<!-- recupera caminho do contexto e configura uma variável com este valor -->
<c:set var="ctx" value="${pageContext.request.contextPath}" scope="request" />

<!-- usa a variável -->
<a href="${ctx}/site/pagina.jsp" />

• Using JSP scriptlet: if you are not using JSTL, you can do something less friendly by recovering more or less like this:

<!-- recupera caminho do contexto e configura uma variável com este valor -->
<%
String ctx = request.getContextPath();
%>

<!-- usa a variável -->
<a href="<%=ctx%>/site/pagina.jsp" />

Or directly:

<a href="<%=request.getContextPath()%>/site/pagina.jsp" />