Using Jena Api in Java Web… Unknown Exception

Did anyone encountered this exception while using Jena in Java Web Application... Please Kindly help me ..

Here is my servlet code

package com.mycompany.servlet;

import java.io.IOException;
import java.util.Iterator;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
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 com.hp.hpl.jena.query.QueryExecution;
import com.hp.hpl.jena.query.QueryExecutionFactory;
import com.hp.hpl.jena.query.QueryFactory;
import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.rdf.model.ModelFactory;

import com.hp.hpl.jena.ontology.*;


/**
 * Servlet implementation class GreetingServlet
 */
@WebServlet("/GreetingServlet")
public class GreetingServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public GreetingServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        String SOURCE ="file:E:\\healthcare.owl";

        OntModel base =  ModelFactory.createOntologyModel( OntModelSpec.OWL_MEM );
        base.read( SOURCE );


        for (Iterator<OntClass> i = base.listClasses(); i.hasNext(); ) 
        {

        OntClass c = i.next();              

        //System.out.println( "Class" + c.getLocalName());

        }
    }

    }

Exception is HTTP Status 500 -

type Exception report

message

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

exception

javax.servlet.ServletException: Error instantiating servlet class com.mycompany.servlet.GreetingServlet
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
    org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
    java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    java.lang.Thread.run(Unknown Source)

root cause

java.lang.NoClassDefFoundError: com/hp/hpl/jena/rdf/model/Model
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    java.lang.Class.getConstructor0(Unknown Source)
    java.lang.Class.newInstance0(Unknown Source)
    java.lang.Class.newInstance(Unknown Source)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
    org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
    java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    java.lang.Thread.run(Unknown Source)

root cause

java.lang.ClassNotFoundException: com.hp.hpl.jena.rdf.model.Model
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1676)
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1521)
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    java.lang.Class.getConstructor0(Unknown Source)
    java.lang.Class.newInstance0(Unknown Source)
    java.lang.Class.newInstance(Unknown Source)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
    org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
    java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    java.lang.Thread.run(Unknown Source)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.11 logs.

回答1:

root cause

java.lang.ClassNotFoundException: com.hp.hpl.jena.rdf.model.Model

That means that tomcat can't find the Jena libraries. Make sure you have all the right jars in the right place.

回答2:

You need to copy each of the *.jar files from $JENA/lib (where $JENA is the directory you installed your local installation of Jena into) to the WEB-INF/lib directory of your servlet application.

回答3:

just copy the jena jars declared on the build path project to the lib directory of tomcat, in my case it is located at