在 Java Web 中使用 Jena Api...未知异常

Question

有没有人在 Java Web 应用程序中使用 Jena 时遇到此异常...请帮助我..

这是我的 servlet 代码，

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());

        }
    }

    }

异常是 HTTP 状态 500 -

---

类型 异常报告

消息

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

异常

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)

根本原因

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)

根本原因

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)

注意 Apache Tomcat/7.0.11 日志中提供了根本原因的完整堆栈跟踪。

---

Answer 1

root cause

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

这意味着 tomcat 找不到 Jena 库。确保所有正确的罐子都放在正确的位置。

Answer 2

您需要从 $JENA/lib 复制每个 *.jar 文件（其中 $JENA 是您本地安装的目录） Jena into）到 servlet 应用程序的 WEB-INF/lib 目录。

Answer 3

只需将构建路径项目上声明的 jena jar 复制到 tomcat 的 lib 目录，在我的例子中它位于

C:\Apache Software Foundation\Tomcat 6.0\lib