I created a simple JSP/Servlet project for calculating the monthly payment. However, when I make an HTTP request on my localhost, I receive the following error:
HTTP Status 500 – Internal Server Error
Type Exception Report
message Unable to compile class for JSP:
description The server encountered an internal error that prevented it from fulfilling the request.
Exception:
org.apache.jasper.JasperException: Impossible de compiler la classe pour la JSP:
Une erreur s'est produite à la ligne : [3] dans le fichier jsp : [/ServletJsp.jsp]
req cannot be resolved
1: <%@ page import="web.CreditModel"%>
2: <%
3: CreditModel model = (CreditModel) req.getAttribute("creditModel");
4:
5: %>
6: <!DOCTYPE html>
Stacktrace:
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:102)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:214)
org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:531)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:398)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:368)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:352)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:603)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:399)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:379)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:327)
javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
web.ControllerServlet.doGet(ControllerServlet.java:25)
javax.servlet.http.HttpServlet.service(HttpServlet.java:529)
javax.servlet.http.HttpServlet.service(HttpServlet.java:623)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
note The complete trace of the root cause of this error is available in the log files of this server.
This is the code of the servlet that calls:
ControllerServlet.java:
package web;
import metier.CreditMetier;
import metier.CreditMetierImpl;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet("/hi")
public class ControllerServlet extends HttpServlet {
private CreditMetier metier;
@Override
public void init() throws ServletException {
metier = new CreditMetierImpl();
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setAttribute("creditModel", new CreditModel());
req.getRequestDispatcher("ServletJsp.jsp").forward(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
double montant = Double.parseDouble(req.getParameter("montant"));
double taux = Double.parseDouble(req.getParameter("taux"));
int duree = Integer.parseInt(req.getParameter("duree"));
CreditModel model = new CreditModel();
model.setMontant(montant);
model.setTaux(taux);
model.setDuree(duree);
double result = metier.calculerMensualiterCredit(montant,taux,duree);
model.setResultat(result);
req.setAttribute("creditModel", model);
req.getRequestDispatcher("ServletJsp.jsp").forward(req,resp);
}
}
and this is the code of the JSP that calls:
ServletJsp.jsp:
<%@ page import="web.CreditModel"%>
<%
CreditModel model = (CreditModel) req.getAttribute("creditModel");
%>
<!DOCTYPE html>
<html>
<head>
<title> Crédit bancaire </title>
<meta charset = "utf-8">
<link rel= "stylesheet" type="text/css" href="css/style.css"/>
</head>
<body>
<div>
<form action="hi" method="post">
<table>
<tr>
<td> Montant:</td>
<td><input type="text" name="montant"/></td>
<td>DH</td>
</tr>
<tr>
<td> Taux:</td>
<td><input type="text" name="taux"/></td>
<td>%</td>
</tr>
<tr>
<td> Duree:</td>
<td><input type="text" name="duree"/></td>
<td>mois</td>
</tr>
</table>
<button type="submit">Calculer</button>
</form>
</div>
<div>
<p> Mensualite = <%=model.getResultat() %> </p>
</div>
</body>
</html>
this is the code of the metier that calls
CreditMetierImpl.java:
package metier;
public class CreditMetierImpl implements CreditMetier{
@Override
public double calculerMensualiterCredit(double capital, double taux, int duree) {
double t = taux/100;
double t1 = capital* t/12;
double t2 = 1 - Math.pow(1 +t/12, -duree);
return t1/t2;
}
}
and the code of model that calls
CreditModel.java:
package web;
public class CreditModel {
private double montant;
private double taux;
private int duree;
private double mensualite;
private double resultat;
public double getMontant() {
return montant;
}
public void setMontant(double montant) {
this.montant = montant;
}
public double getTaux() {
return taux;
}
public void setTaux(double taux) {
this.taux = taux;
}
public int getDuree() {
return duree;
}
public void setDuree(int duree) {
this.duree = duree;
}
public double getMensualite() {
return mensualite;
}
public void setMensualite(double mensualite) {
this.mensualite = mensualite;
}
public double getResultat() {
return resultat;
}
public void setResultat(double resultat) {
this.resultat = resultat;
}
}
I tried the HTTP request with get but it's not working.
You've got a compilation error
req cannot be resolved
because req is a method's local parameter. When a method doGet() ends then it won't be available anywhere in the code, including a JSP, which is compiled to another servlet.
You use scriptlets in the JSP. They are frequently written on Java and a code can be moved to a servlet for further references with EL expressions.
So, you need to remove a scriptlet code from the head of JSP. And this code can be replaced
<p> Mensualite = <%=model.getResultat() %> </p>
With
<p> Mensualite = ${model.resultat} </p>