getquestionaction.java

老外的在线考试

/*
 * CyberTester - J2EE Web application for creating, delivering and managing tests/exams/surveys. 
 * Copyright (C) 2003 CyberDemia Research and Services Pty Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (see the file COPYING); if not, write to the
 * Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * See the COPYING file located in the top-level-directory of
 * the archive of this program for complete text of license.
 */
package com.cyberdemia.cybertester.student.test;

import javax.servlet.*;
import javax.servlet.http.*;
import org.apache.struts.action.*;
import com.cyberdemia.school.*;
import com.cyberdemia.cybertester.*;
import com.cyberdemia.cybertester.student.StudentConstants;
import java.util.logging.*;

/**
 * 
 * GetQuestionAction is a Struts action to load a question's data
 * to be served to the user during a test with its "multiQuestionsMode" disabled. 
 *  
 * @author Alexander Yap
 */
public final class GetQuestionAction extends AbstractUserAction
{
	protected ActionForward doPerform(
		ActionMapping mapping, ActionForm form,
		HttpServletRequest request, HttpServletResponse response,
		HttpSession session) throws Exception	
	{
		Logger logger = CyberTesterUtils.getLogger();
		int index = 0;
		String indexStr = CyberTesterUtils.getParameterOrRequestAttribute(request, StudentConstants.QUESTION_INDEX_KEY);
		if (indexStr!=null)
		{
			try
			{
				index = Integer.parseInt(indexStr);
			}
			catch (NumberFormatException nfex)
			{
				throw new ServletException( "Invalid Question index "+indexStr);
			}
		}

		QuestionData[] questions = (QuestionData[])session.getAttribute( StudentConstants.QUESTION_LIST_KEY);
		if (questions==null)
		{
			throw new ServletException("Missing session attribute "+StudentConstants.QUESTION_LIST_KEY);
		}

		if ((index<0) || (index>=questions.length))
		{
			throw new ServletException("Question index "+indexStr+" is out of range.");
		}

		QuestionData ques = questions[index];		
		request.setAttribute( StudentConstants.QUESTION_DATA_KEY, ques );
		
		if (form==null)
		{
			form = new QuestionForm();
			if ("request".equals(mapping.getScope()))
				request.setAttribute(mapping.getAttribute(), form);
			else
				session.setAttribute(mapping.getAttribute(), form);
		}
		QuestionForm questionForm = (QuestionForm)form;
		questionForm.setQuesIndex(index);
		questionForm.setQuesId(ques.getId());
		request.setAttribute(StudentConstants.QUESTION_INDEX_KEY, indexStr);
		if (request.getAttribute(StudentConstants.ANSWER_RECEIVED_KEY)!=null)
		{
			if (index<questions.length-1)
			{
				request.setAttribute(StudentConstants.NEXT_QUESTION_INDEX_KEY, new Integer(index+1));
			}
		}
		
		String testId = (String)session.getAttribute(StudentConstants.TEST_ID_KEY);
		StudentTestUtils.storeQuestionTimeToken(session, testId, ques.getId());
		// Set a transactional control token to prevent double posting
		saveToken(request);
		return mapping.findForward(Constants.SUCCESS);
	}
	
}