checkansweraction.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.*;

/**
 * 
 * CheckAnswerAction is a Struts action to receive and check the user's answer
 * to a single question. It is called for each question in a test that has its
 * "multiQuestionsMode" disabled.
 *  
 * @author Alexander Yap
 */
public final class CheckAnswerAction extends AbstractUserAction
{
	protected ActionForward doPerform(
		ActionMapping mapping, ActionForm form,
		HttpServletRequest request, HttpServletResponse response,
		HttpSession session) throws Exception
	{
		int index = 0;
		String indexStr = request.getParameter(StudentConstants.QUESTION_INDEX_KEY);
		if (indexStr!=null)
		{
			try
			{
				index = Integer.parseInt(indexStr);
			}
			catch (NumberFormatException nfex)
			{
				throw new ServletException( "Invalid Question index "+indexStr);
			}
		}
		else
		{
			throw new ServletException("Missing parameter "+StudentConstants.QUESTION_INDEX_KEY);
		}

		ActionErrors errors = new ActionErrors();
		QuestionData[] questions = (QuestionData[])session.getAttribute( StudentConstants.QUESTION_LIST_KEY);
		if (questions==null)
		{
			errors.add(ActionErrors.GLOBAL_ERROR, new ActionError("error.transaction.token"));
		}

		QuestionData quesData = null;
		if (errors.isEmpty())
		{
			if ((index<0) || (index>=questions.length))
			{
				throw new ServletException("Question index "+indexStr+" is out of range.");
			}
			quesData = questions[index];
			// If submitted out of order, go to error page immediately.
			if (!isTokenValid(request))
			{
				errors.add(ActionErrors.GLOBAL_ERROR, new ActionError("error.transaction.token"));
			}
		}
		
		resetToken(request);
		String testId = (String)session.getAttribute(StudentConstants.TEST_ID_KEY);
		TestData testData = (TestData)session.getAttribute(StudentConstants.TEST_DATA_KEY);
		if (testData==null)
		{
			throw new ServletException( "Missing session attribute "+StudentConstants.TEST_DATA_KEY);
		}
	
		if (errors.isEmpty())
		{
			int timeSecs = (int)(StudentTestUtils.checkQuestionTimeToken(session,testId,quesData.getId())/1000);
			request.setAttribute(StudentConstants.ANSWER_RECEIVED_KEY,Boolean.TRUE);
			QuestionForm quesForm = (QuestionForm)form;
			try
			{
				TestManagerHome testMgrHome = CyberTesterUtils.getTestManagerHome();
				TestManager testMgr = (TestManager)testMgrHome.create();
				Integer userAnswer = new Integer(quesForm.getAnswer());
				int status = testMgr.checkQuestionAnswer(testId, quesData.getId(), (String)session.getAttribute(Constants.USER_ID_KEY), index, userAnswer, 0, timeSecs);
				
				switch (status)
				{
					case IAnswerStatus.CORRECT:
						request.setAttribute(StudentConstants.CORRECT_ANSWER_KEY,Boolean.TRUE);					
						break;
					case IAnswerStatus.QUESTION_TIMED_OUT:
						request.setAttribute(StudentConstants.QUESTION_TIMED_OUT_KEY,Boolean.TRUE);
						break;
					default:
						request.setAttribute(StudentConstants.WRONG_ANSWER_KEY,Boolean.TRUE);	
				}
			}
			catch (Exception ex)
			{
				CyberTesterUtils.getLogger().log( Level.SEVERE, "Error checking answer.", ex);
				errors.add(ActionErrors.GLOBAL_ERROR, new ActionError("error.checking.answer",String.valueOf(quesForm.getAnswer()),ex.getMessage()));
			}

			if (index==questions.length-1)
			{
				request.setAttribute(StudentConstants.TEST_ID_KEY, testId);				
				request.setAttribute(StudentConstants.TEST_DATA_KEY, session.getAttribute(StudentConstants.TEST_DATA_KEY));
				// End of the question list in the test, clean up the session
				session.removeAttribute(StudentConstants.TEST_ID_KEY);
				session.removeAttribute(StudentConstants.TEST_DATA_KEY);
				session.removeAttribute(StudentConstants.QUESTION_LIST_KEY);
			}
		}


		if (!errors.isEmpty())
		{
			saveErrors(request, errors);
			return mapping.findForward(Constants.ERROR);
		}
		
		String forwardTarget = null;
		if (testData.isSuppressQuestionFeedback())
		{
			// Go directly to the next question if any.
			// If end of test, go directly to the results view
			if (index<questions.length-1)
			{
				request.setAttribute(StudentConstants.QUESTION_INDEX_KEY, String.valueOf(index+1) );
				forwardTarget = "nextQuestion";
			}
			else
			{
				forwardTarget = "viewResults";
			}
		}
		else
		{
			// Return the feedback to the question page
			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(quesData.getId());
			request.setAttribute( StudentConstants.QUESTION_DATA_KEY, quesData );
			request.setAttribute(StudentConstants.QUESTION_INDEX_KEY, indexStr );
			forwardTarget = "feedback";
			if (index<questions.length-1)
			{
				request.setAttribute(StudentConstants.NEXT_QUESTION_INDEX_KEY, new Integer(index+1));
			}
		}
		
		return mapping.findForward(forwardTarget);

	}

}