Servlets – infinite loop when forwarding requests in Java servlets

I hope you can help me solve the problem I face:

I created a simple web application using NetBeans Up to now, this is very basic

>The servlet receives requests in the / verificon / * URL mode. > It extracts any string set after / verificon /, that is, if the web address is http: / / domain / context / verificon / blahblah, it extracts blahblah. > It checks whether such a string is a known string and displays only the JSP with the result (true / false)

However, despite its simplicity, the following error occurred when running the application using the test string:

javax.servlet.ServletException: 
The server side component of the HTTP Monitor has detected a java.lang.StackOverflowError.
This happens when there is an infinite loop in the web module.
Correct the cause of the infinite loop before running the web module again.

org.netbeans.modules.web.monitor.server.MonitorFilter.rethrow(MonitorFilter.java:1648)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:473)
mx.tegu.kdor.web.iu.ServletVerificon.processRequest(ServletVerificon.java:51)
mx.tegu.kdor.web.iu.ServletVerificon.doGet(ServletVerificon.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
mx.tegu.kdor.web.iu.ServletVerificon.processRequest(ServletVerificon.java:51)
mx.tegu.kdor.web.iu.ServletVerificon.doGet(ServletVerificon.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
mx.tegu.kdor.web.iu.ServletVerificon.processRequest(ServletVerificon.java:51)
mx.tegu.kdor.web.iu.ServletVerificon.doGet(ServletVerificon.java:70)
    ...

Then it repeats itself

The processrequest method of my servlet is as follows Testdata is just an auxiliary class. If the string is known, it returns a mapeo object. If it is not known, it returns null

protected void processRequest(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
request.setCharacterEncoding("UTF-8");

String h = request.getRequestURI().replaceFirst(request.getContextPath() + "/verificon/","");

TestData td = TestData.getInstance();

Mapeo m = td.getMapeo(h);

boolean valido = false;
if(m != null) {
  valido = true;
}

request.setAttribute("valido",valido);

/*
PrintWriter out = response.getWriter();
out.write("Válido?: " + valido);
out.close();
*/

String respuesta = "WEB-INF/jsp/resultado.jsp";
// Como regla general,forward se utiliza para los GET y sendRedirect para los POST
RequestDispatcher rd = request.getRequestDispatcher(respuesta);
rd.forward(request,response);

}

Any help would be appreciated

If you need any other information, please let me know

thank you!

Note 1: Line 51 of the servlet calls rd.forward() at the end of the processrequest method, and line 70 just calls processrequest() from the doget method Note 2: if I comment on the forward section and uncomment the printwriter section, everything works as expected Note 3: Resultado JSP is a pure HTML page with correct DOCTYPE, def, HTML, head and body tags. This: <% Boolean Valido = (Boolean) request getAttribute(“valido”);％> … <％ If (Valido) {% > < p is h. Valido < / P is h. <%} else {% > < p is h. inv á Lido < / P is h. <%}% >

Solution

Look here,

String respuesta = "WEB-INF/jsp/resultado.jsp";
RequestDispatcher rd = request.getRequestDispatcher(respuesta);
// ...

You use relative path forwarding It is forwarded to http://domain/context/verificon/blahblah/web-inf/jsp/resultado.com JSP, which again matches the servlet Then use the relative path to forward to http://domain/context/verificon/blahblah/web-inf/jsp/resultado.com jsp/WEB-INF/jsp/resultado. JSP, which again matches the servlet wait. If you have debugged / logged the incoming request URI, it will make everything clearer

You need to use absolute path forwarding Use / prefix

String respuesta = "/WEB-INF/jsp/resultado.jsp";
// ...

It has nothing to do with the specific problem. The way you check values in JSP is very clumsy and old-fashioned Just use el (it's been around for more than a decade to make sure you're reading the right JSP / servlet books / tutorials):

<p>${valido ? 'Válido' : 'Inválido'}</p>