questionmanagerbean.java

老外的在线考试

/*
 * SchoolEJB - CyberDemia's library of EJBs for educational related services.
 * Copyright (C) 2004 CyberDemia Research and Services
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; 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 library for complete text of license.
 */
package com.cyberdemia.school;
import javax.ejb.*;
import javax.naming.*;
import java.util.*;
import java.util.logging.*;
import com.cyberdemia.ejb.BaseSessionBean;

/**
 * QuestionManager is a facade that provides useful methods for managing questions.
 *
 * @ejb.bean name="QuestionManagerBean"
 *           type="Stateless"
 *           view-type="remote"
 *           jndi-name="ejb/QuestionManager"
 *
 * @ejb.util generate="physical"
 * @ejb.interface remote-class="com.cyberdemia.school.QuestionManager" extends="javax.ejb.EJBObject"
 * @ejb.home remote-class="com.cyberdemia.school.QuestionManagerHome" extends="javax.ejb.EJBHome"
 * @ejb.ejb-ref ejb-name="QuestionBean" ref-name="ejb/LocalQuestion" view-type="local"
 * @ejb.ejb-ref ejb-name="AnswerChoiceBean" ref-name="ejb/LocalAnswerChoice" view-type="local"
 *
 * @author Alexander Yap
 * @version $Revision: 1.8 $ at $Date: 2004/06/20 16:05:17 $ by $Author: alexycyap $
 *
 */
public class QuestionManagerBean extends BaseSessionBean
{

	/**
	 * Adds a new question to the database. 
	 * Parameter answerChoicesDefined is provided to support a two-stage question creation
	 * mechanism where the answer choices are only added in the latter stage. 
	 * In this case, when the question is first created, the answer choices are not created,
	 * and the question is marked as inactive.
	 *
	 * @ejb.interface-method
	 * @ejb.transaction type="Required"
	 *
	 * @param data QuestionData instance with the data for the new question.
	 * @param answerChoicesDefined true if answer choices are already defined, false if they are not yet defined. 
	 * @return The unique ID of the new question.
	 * @throws SchoolException if there is a problem creating the question.
	 */
	public Integer addQuestion(QuestionData data, boolean answerChoicesDefined) throws SchoolException
	{
		s_logger.log( Level.FINE, "Creating new Question name="+data.getName());
		Integer id = null;
		try
		{
			LocalQuestion ques = s_quesHome.create(
				data.getName(), data.getQuestion(),
				data.getAnswer(),
				data.getHint(), data.getDifficulty(),
				data.getExplanation(), data.getType(), 
				data.getTimeLimitSeconds(), data.getScore(), 
				answerChoicesDefined, data.isMustMatchAllKeywords() );
			
			if (answerChoicesDefined && (data.isSingleChoiceType() || data.isMultipleChoiceType()) )
			{
				String[] answerChoices = data.getAnswerChoices();
				for (int c=0; c<answerChoices.length; c++)
				{
					ques.addAnswerChoice( s_answerChoiceHome.create(c, answerChoices[c]) );
				}
			}
			id = ques.getGeneratedPrimaryKey();
			s_logger.log( Level.FINE, "New Question name="+data.getName()+" successfully created. Answers "+(answerChoicesDefined ? "already" : "not")+" defined.");
		}
		catch (CreateException cex)
		{
			getSessionContext().setRollbackOnly();
			throw new SchoolException("Error creating Question "+data.getName(), cex);
		}
		return id;
	}

	/**
	 * Deactives the specified question, after which it may be considered to 
	 * be logically removed from the system.
	 * This method may perform some checks first to ensure that the question
	 * can be safely deactivated.
	 *
	 * @ejb.interface-method
	 * @ejb.transaction type="Required"
	 *
	 * @param id Question ID
	 * @return true if the question is deactivated, false if it is not (either a problem or it is already inactive) 
	 * @throws SchoolException if the question can't be found.
	 */
	public boolean deactivateQuestion(Integer id) throws SchoolException
	{
		LocalQuestion ques =  null;
		try
		{
			ques = s_quesHome.findByPrimaryKey(id);
		}
		catch (FinderException fex)
		{
			throw new SchoolException(SchoolException.QUESTION_NOT_FOUND, "Cannot find Question with ID "+id, fex);
		}

		boolean success = false;
		try
		{
			ques.setLastModifiedMillis( System.currentTimeMillis() );
			success = ques.deactivate();
		}
		catch (Exception ex)
		{
			getSessionContext().setRollbackOnly();
			throw new SchoolException("Error deactivating Question with ID "+id, ex);
		}
		return success;
	}

	/**
	 * Gets list of questions from database.
	 *
	 * @ejb.interface-method
	 * @ejb.transaction type="Required"
	 *
	 * @param activeOnly true to only return active questions, false to return all questions.
	 * @return Array of QuestionData instances.
	 */	
	public QuestionData[] getQuestions(boolean activeOnly)
	{
		QuestionData[] dataArr = null;
		try
		{
			Iterator quesIter = activeOnly ? s_quesHome.findAllActive().iterator() : s_quesHome.findAll().iterator();
			ArrayList dataList = new ArrayList();
			while (quesIter.hasNext())
			{
				LocalQuestion ques = (LocalQuestion)quesIter.next();
				dataList.add( getDataFromQuestion(ques) );
			}
			dataArr = (QuestionData[])dataList.toArray(new QuestionData[0]);
		}
		catch (Exception ex)
		{
			// If there is a problem finding questions, just return empty array
			dataArr = new QuestionData[0];
		}
		return dataArr;
	}
	
	/**
	 * Gets Ids of active questions that belong to specified test.
	 * If testId is null or an empty String, this methods gets all questions that 
	 * are not assigned to any test.
	 *
	 * @ejb.interface-method
	 * @ejb.transaction type="Required"
	 *
	 * @param testId Test Id
	 * @return Array of QuestionData instances.
	 */
	public QuestionData[] getQuestionsByTest(Integer testId)
	{
		QuestionData[] dataArr = null;
		try
		{
			Collection quesCol = null;
            if (testId!=null)
            {
            	quesCol = s_quesHome.findByTest( testId );
            }
            else
            {
                quesCol = s_quesHome.findUnassignedToTest(true);
            }
			s_logger.fine("Retrieved "+quesCol.size()+" LocalQuestions.");
			Iterator quesIter = quesCol.iterator();
			ArrayList dataList = new ArrayList();
			while (quesIter.hasNext())
			{
				LocalQuestion ques = (LocalQuestion)quesIter.next();
				dataList.add( getDataFromQuestion(ques) );
			}
			dataArr = (QuestionData[])dataList.toArray(new QuestionData[0]);
		}
		catch (Exception ex)
		{
			// If there is a problem finding questions, just return empty array
			dataArr = new QuestionData[0];
		}
		return dataArr;
	}
	
	/**
	 * Gets the data of a specified question.
	 *
	 * @ejb.interface-method
	 * @ejb.transaction type="Required"
	 *
	 * @param id Question ID.
	 * @return QuestionData instance storing the question's data.
	 * @throws SchoolException if the question can't be found.
	 */
	public QuestionData getQuestionData(Integer id) throws SchoolException
	{
		LocalQuestion ques =  null;
		try
		{
			ques = s_quesHome.findByPrimaryKey(id);
		}
		catch (FinderException fex)
		{
			throw new SchoolException(SchoolException.QUESTION_NOT_FOUND, "Cannot find Question with ID "+id, fex);
		}

		QuestionData data = null;
		try
		{
			data = getDataFromQuestion(ques);
		}
		catch (Exception ex)
		{
			throw new SchoolException( "Error getting data of Question with ID "+id, ex);
		}
		return data;
	}

	/**
	 * Sets the data of a specified question.
	 *
	 * @ejb.interface-method
	 * @ejb.transaction type="Required"
	 *
	 * @param id Question ID.
	 * @param data QuestionData instance with the question's data.
	 * @throws SchoolException if the question can't be found.
	 */
	public void setQuestionData(Integer id, QuestionData data) throws SchoolException
	{
		LocalQuestion ques =  null;
		try
		{
			ques = s_quesHome.findByPrimaryKey(id);
		}
		catch (FinderException fex)
		{
			throw new SchoolException(SchoolException.QUESTION_NOT_FOUND, "Cannot find Question with ID "+id, fex);
		}

		try
		{
			ques.setName(data.getName());
			ques.setContent( data.getQuestion());
			ques.setHint(data.getHint());
			ques.setDifficulty(data.getDifficulty());
			ques.setExplanation(data.getExplanation());
			ques.setTimeLimitSeconds(data.getTimeLimitSeconds());
			ques.setLastModifiedMillis( System.currentTimeMillis() );
			ques.setActive(data.isActive());
			ques.setAnswer(data.getAnswer());
			ques.setMustMatchAllKeywords(data.isMustMatchAllKeywords());
			ques.setScore(data.getScore());
			// The type cannot be changed for an existing question
			
			if (data.isSingleChoiceType() || data.isMultipleChoiceType())
			{
				String[] answerChoices = data.getAnswerChoices();
				for (int c=0; c<answerChoices.length; c++)
				{
					if (!ques.setAnswerChoiceText( c, answerChoices[c] ))
					{
						ques.addAnswerChoice( s_answerChoiceHome.create(c, answerChoices[c]) );
					}
				}				
			}
			
		}
		catch (Exception ex)
		{
			getSessionContext().setRollbackOnly();
			throw new SchoolException( "Error setting data for Question with ID "+id, ex);
		}
	}

    /**
     * Dummy create method.
     *
     * @ejb.create-method view-type="remote"
     */
    public void ejbCreate()
    {
        // Nothing here
    }

	private QuestionData getDataFromQuestion(LocalQuestion ques)
	{
		QuestionData data = new QuestionData();
		data.setId(ques.getId());
		data.setName(ques.getName());
		data.setQuestion(ques.getContent());
		data.setAnswer(ques.getAnswer());
		data.setHint(ques.getHint());
		data.setType(ques.getType());
		data.setScore(ques.getScore());
		data.setDifficulty(ques.getDifficulty());
		data.setExplanation(ques.getExplanation());
		data.setCanDeactivate(ques.isActive() && (ques.getTest()==null));
		data.setTimeLimitSeconds(ques.getTimeLimitSeconds());
		data.setActive(ques.isActive());
		data.setMustMatchAllKeywords(ques.isMustMatchAllKeywords());
		
		if (data.isSingleChoiceType() || data.isMultipleChoiceType())
		{
			LocalAnswerChoice[] answerChoices = ques.getAnswerChoices();
			String[] answerChoicesData = new String[answerChoices.length];
			Arrays.fill(answerChoicesData, "");
			for (int c=0; c<answerChoices.length; c++)
			{
				if (answerChoices[c]!=null)
				{
					answerChoicesData[answerChoices[c].getAnswerIndex()] = answerChoices[c].getAnswerText();
				}
			}
			data.setAnswerChoices(answerChoicesData);
		}
		else
		{
			data.setAnswerChoices(null);
		}
		return data;
	}

	private static LocalQuestionHome s_quesHome = null;
	private static LocalAnswerChoiceHome s_answerChoiceHome = null;
	static
	{
		try
		{
			Context ctx = new InitialContext();
			try
			{
				s_quesHome = (LocalQuestionHome)ctx.lookup(JNDI_PREFIX+LocalQuestionHome.JNDI_NAME);
				s_answerChoiceHome = (LocalAnswerChoiceHome)ctx.lookup(JNDI_PREFIX+LocalAnswerChoiceHome.JNDI_NAME);
			}
			finally
			{
				ctx.close();
			}
		}
		catch (NamingException nex)
		{
			throw new EJBException("Error retrieving homes", nex);
		}
	}


	private static Logger s_logger = Logger.getLogger( QuestionManagerBean.class.getName());
}