questionmanagerbean.java

老外的在线考试

/*
 * SchoolEJB - CyberDemia's library of EJBs for educational related services.
 * Copyright (C) 2003 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.impl;
import javax.ejb.*;
import javax.naming.*;
import java.util.*;
import com.cyberdemia.school.*;
import java.util.logging.*;

/**
* QuestionManagerBean is a session bean implementation
* of QuestionManager.
*
* @author Alexander Yap
*/
public class QuestionManagerBean implements SessionBean
{
	/**
	 * 
	 * Creates an instance of QuestionManagerBean.
	 *
	 */
	public QuestionManagerBean()
	{
		try
		{
			Context ctx = new InitialContext();
			m_quesHome = (LocalQuestionHome)ctx.lookup("java:comp/env/ejb/localQuestion");
			m_answerChoiceHome = (LocalAnswerChoiceHome)ctx.lookup("java:comp/env/ejb/localAnswerChoice");
		}
		catch (NamingException nex)
		{
			throw SchoolUtils.convertToEJBException(nex);
		}
		
	}

	/**
	 * Adds a new question to the database. 
	 * @param data QuestionData instance with the data for the new question.
	 * @return The unique ID of the new question.
	 * @throws EJBException if there is a problem creating the question.
	 */
	public String addQuestion(QuestionData data)
	{
		String id = null;
		try
		{
			LocalQuestion ques = m_quesHome.create(
				data.name, data.question,
				data.answer,
				data.hint, data.difficulty,
				data.explanation, data.timeLimitSeconds );
				
			for (int c=0; c<data.answerChoices.length; c++)
			{
				ques.addAnswerChoice( m_answerChoiceHome.create(ques.getId()+"_"+c, c, data.answerChoices[c]) );
			}
			id = ques.getId();

		}
		catch (CreateException cex)
		{
			s_logger.log( Level.SEVERE, "Error creating Question "+data.name, cex);
			throw SchoolUtils.convertToEJBException(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.
	 * 
	 * @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 EJBException if the question can't be found.
	 */
	public boolean deactivateQuestion(String id)
	{
		boolean success = false;
		try
		{
			LocalQuestion ques = m_quesHome.findByPrimaryKey(id);
			ques.setLastModifiedMillis( System.currentTimeMillis() );
			success = ques.deactivate();
		}
		catch (FinderException fex)
		{
			throw SchoolUtils.convertToEJBException(fex);
		}
		return success;
	}

	/**
	 * Gets list of questions from database.
	 * @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 ? m_quesHome.findAllActive().iterator() : m_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 (FinderException fex)
		{
			throw SchoolUtils.convertToEJBException(fex);
		}
		return dataArr;
	}
	
	/**
	 * Gets Ids of 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.
	 * @param testId Test Id
	 * @return Array of QuestionData instances.
	 */
	public QuestionData[] getQuestionsByTest(String testId)
	{
		QuestionData[] dataArr = null;
		try
		{
			Collection quesCol = m_quesHome.findByTest( ((testId!=null) ? testId :"") );
			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 (FinderException fex)
		{
			throw SchoolUtils.convertToEJBException(fex);
		}
		return dataArr;
	}
	
	/**
	 * Gets the data of a specified question.
	 * @param id Question ID.
	 * @return QuestionData instance storing the question's data.
	 * @throws EJBException if the question can't be found.
	 */
	public QuestionData getQuestionData(String id)
	{
		QuestionData data = null;
		try
		{
			LocalQuestion ques = m_quesHome.findByPrimaryKey(id);
			data = getDataFromQuestion(ques);
		}
		catch (FinderException fex)
		{
			s_logger.log( Level.SEVERE, "Error finding Question ID="+id, fex);
			throw SchoolUtils.convertToEJBException(fex);
		}
		return data;
	}

	/**
	 * Sets the data of a specified question.
	 * @param id Question ID.
	 * @param data QuestionData instance with the question's data.
	 * @throws EJBException if the question can't be found.
	 */
	public void setQuestionData(String id, QuestionData data)
	{
		try
		{
			LocalQuestion ques = m_quesHome.findByPrimaryKey(id);
			ques.setName(data.name);
			ques.setContent( data.question );
			ques.setAnswer(data.answer);
			ques.setHint(data.hint);
			ques.setDifficulty(data.difficulty);
			ques.setExplanation(data.explanation);
			ques.setTimeLimitSeconds(data.timeLimitSeconds);
			ques.setLastModifiedMillis( System.currentTimeMillis() );
			for (int c=0; c<data.answerChoices.length; c++)
			{
				ques.setAnswerChoiceText( c, data.answerChoices[c] );
			}
		}
		catch (FinderException fex)
		{
			throw SchoolUtils.convertToEJBException(fex);
		}
	}

	private QuestionData getDataFromQuestion(LocalQuestion ques)
	{
		QuestionData data = new QuestionData();
		data.id = ques.getId();
		data.name = ques.getName();
		data.question = ques.getContent();
		data.answer = ques.getAnswer();
		data.hint = ques.getHint();
		data.difficulty = ques.getDifficulty();
		data.explanation = ques.getExplanation();
		data.canDeactivate = ques.isActive() && "".equals(ques.getTestId());
		data.timeLimitSeconds = ques.getTimeLimitSeconds();
		
		LocalAnswerChoice[] answerChoices = ques.getAnswerChoices();
		data.answerChoices = new String[answerChoices.length];
		for (int c=0; c<answerChoices.length; c++)
		{
			if (answerChoices[c]!=null)
			{
				data.answerChoices[c] = answerChoices[c].getAnswerText();
			}
			else
			{
				data.answerChoices[c] = "";
			}
		}
		return data;
	}

	public void ejbCreate() {}
	public void ejbPostCreate() { }
	public void ejbRemove() {}
	public void ejbActivate() {}
	public void ejbPassivate() {}
	
	public void setSessionContext(SessionContext sc) 
	{
		m_context = sc;
	}

	private SessionContext m_context = null;
	private LocalQuestionHome m_quesHome = null;
	private LocalAnswerChoiceHome m_answerChoiceHome = null;
	private static Logger s_logger = Logger.getLogger( QuestionManagerBean.class.getName());
}