questionbean.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 com.cyberdemia.util.UniqueIdGenerator;
import com.cyberdemia.school.*;
import java.util.*;

/**
* QuestionBean is the EJB implementation of a multiple-choice question. 
* It is a AbstractTextResource with additional properties
* such as answer, hint, etc. to model a multiple-choice 
* question. It can be persisted to database.
*
* @author Alexander Yap
*/
public abstract class QuestionBean extends AbstractTextResource
{
	/**
	* Gets the answer for this Question. 
	* The answer is an Integer index that refers to one of the 
	* answer choices.
	* This is a CMP field.
	* @return Answer for this Question. 
	*/
	public abstract Integer getAnswer();
	
	/**
	* Sets the answer for this Question. 
	* The answer is an Integer index that refers to one of the 
	* answer choices.
	* This is a CMP field.
	* @param ans Answer for this Question. 
	*/
	public abstract void setAnswer( Integer answer);

	/**
	 * Sets the Set of answer choices.
	 * It is a CMR field.
	 * @param choices Set of answer choices.
	 */
	public abstract void setAnswerChoiceSet( Set choices);
	
	/**
	 * Gets the Set of answer choices.
	 * It is a CMR field.
	 * @return Set of answer choices.
	 */
	public abstract Set getAnswerChoiceSet();

	/**
	* Gets the hint for this question.
	* This is a CMP field.
	* @return Hint for this question.
	*/
	public abstract String getHint();

	/**
	* Sets the hint for this question.
	* This is a CMP field.
	* @param hint Hint for this question.
	*/
	public abstract void setHint( String hint);

	/**
	* Gets the explanation for this question.
	* This is a CMP field.
	* @return Explanation for this question.
	*/
	public abstract String getExplanation();

	/**
	* Sets the explanation for this question.
	* This is a CMP field.
	* @param explain Explanation for this question.
	*/
	public abstract void setExplanation( String explain);

	/**
	* Sets the difficulty code of this question.
	* This method is equivalent to setDifficulty(DifficultyEnum),
	* except that difficulty is specified using its code instead 
	* of DifficultyEnum.
	* This is a CMP field.
	* @param diffCode Difficulty code of this question.
	* @see #setDifficulty(DifficultyEnum)
	*/
	public abstract void setDifficultyCode( Integer diffCode);
	
	/**
	* Gets the difficulty code of this question.
	* This method is equivalent to getDifficulty(),
	* except that difficulty is identified by its code instead 
	* of DifficultyEnum.
	* This is a CMP field.
	* @return Difficulty code of this question.
	* @see #getDifficulty()
	*/
	public abstract Integer getDifficultyCode();

	/**
	 * Gets the score for this question. 
	 * This score is awarded to the user for a correct answer.
	 * This is a CMP field.
	 * @return Score for this question.
	 */
	public abstract int getScore();

	/**
	 * Sets the score for this question. 
	 * This score is awarded to the user for a correct answer.
	 * This is a CMP field.
	 * @param score Score for this question.
	 */
	public abstract void setScore(int score);

	/**
	* Gets the ID of the test that this question is currently assigned to.
	* This is a CMP field.
	* @return Test ID, or empty String if this question not assigned to any test.
	*/
	public abstract String getTestId();

	/**
	* Sets the test ID for this question.
	* This is a CMP field.
	* @param testId Test ID.
	*/
	public abstract void setTestId(String testId);

	/**
	* Sets the allocated time limit (in seconds) for this question.
	* This is a CMP field.
	* @param limit  Time limit in seconds, or 0 (or negative) for no time limit.
	*/
	public abstract void setTimeLimitSeconds(int limit);

	/**
	* Gets the allocated time limit (in seconds) for this question.
	* This is a CMP field.
	* @return  Time limit in seconds, or 0 (or negative) for no time limit.
	*/
	public abstract int getTimeLimitSeconds();

	/**
	 * Checks if this question is active. An active question
	 * may be allocated to a test, editted and used.
	 * An inactive question may be considered to be logically removed
	 * from the system, but is kept in the database to maintain 
	 * consistency in reporting and historical logging.
	 * This is a CMP field.
	 * @return true if this question is active, false if inactive.
	 */
	public abstract boolean getActive();
	
	/**
	 * Sets whether this question is active. An active question
	 * may be allocated to a test, editted and used.
	 * An inactive question may be considered to be logically removed
	 * from the system, but is kept in the database to maintain 
	 * consistency in reporting and historical logging.
	 * This is a CMP field.
	 * @param active true to make this question active, false to make it inactive.
	 */
	public abstract void setActive(boolean active);

	/**
	 * Checks if this question is active. An active question
	 * may be allocated to a test, editted and used.
	 * An inactive question may be considered to be logically removed
	 * from the system, but is kept in the database to maintain 
	 * consistency in reporting and historical logging.
	 * @return true if this question is active, false if inactive.
	 */
	public boolean isActive()
	{
		return getActive();
	}

	/**
	 * Actives this question, so that it may be editted and used.
	 * This method may perform some checks first to ensure that this question
	 * can be safely activated.
	 * @return true if this question is activated, false if it is not (either a problem or it is already active) 
	 */
	public boolean activate()
	{
		// Can always activate as long as it is currently inactive.
		if (!isActive())
		{
			setActive(true);
			return true;
		}
		return false;
	}

	/**
	 * Deactives this question, after which it may be considered to be logically removed
	 * from the system.
	 * This method may perform some checks first to ensure that this question
	 * can be safely deactivated.
	 * @return true if this question is deactivated, false if it is not (either a problem or it is already inactive) 
	 */
	public boolean deactivate()
	{
		// Can only deactivate if it is currently active and not assigned to any Test.
		if (isActive() && "".equals(getTestId()) )
		{
			setActive(false);
			return true;
		}
		return false;
	}

	/**
	* Gets the answer choices as array of LocalAnswerChoice instances. 
	* The answer refers to the index to this array.
	* @return Array of answer choices.
	*/
	public LocalAnswerChoice[] getAnswerChoices()
	{
		Set answerChoiceSet = getAnswerChoiceSet();
		LocalAnswerChoice[] answerChoiceArr = new LocalAnswerChoice[ answerChoiceSet.size()];
		for (int c=0; c<answerChoiceArr.length; c++)
		{	// initalize all elements to null for safety.
			answerChoiceArr[c] = null;
		}
		Iterator answerChoiceIter = answerChoiceSet.iterator();
		while (answerChoiceIter.hasNext())
		{
			LocalAnswerChoice choice = (LocalAnswerChoice)answerChoiceIter.next();
			int index = choice.getAnswerIndex();
			if (index < answerChoiceArr.length)
			{
				answerChoiceArr[ index ] = choice;
			}
		}
		return answerChoiceArr;
	}

	/**
	* Adds an answer choice. 
	* @param choice Answer choice to add.
	*/
	public void addAnswerChoice(LocalAnswerChoice choice)
	{
		if (isActive())
		{
			Set answerChoiceSet = getAnswerChoiceSet();
			answerChoiceSet.add(choice);
		}
	}
	
	/**
	* Sets the text of an existing answer choice. 
	* @param index  Index of answer choice to set.
	* @param text  Text to set.
	*/
	public void setAnswerChoiceText(int index, String text)
	{
		if (isActive())
		{
			Set answerChoiceSet = getAnswerChoiceSet();
			// Find the answer choice with the specified index.
			Iterator choiceIter = answerChoiceSet.iterator();
			while (choiceIter.hasNext())
			{
				LocalAnswerChoice choice = (LocalAnswerChoice)choiceIter.next();
				if (choice.getAnswerIndex()==index)
				{
					choice.setAnswerText(text);
					break;
				}
			}
		}		
	}

	/**
	* Checks the specified response to determine if it
	* matches the answer for this Question.
	* @param response  The response to check.
	* @return true if response matches the answer, otherwise false.
	*/
	public boolean checkResponse( Integer response)
	{
		return response.equals(getAnswer());
	}

	/**
	* Sets the difficulty of this Question.
	* @param diff Difficulty of this Question.
	*/
	public void setDifficulty( DifficultyEnum diff)
	{
		setDifficultyCode(diff.getCode());
	}

	/**
	* Gets the difficulty of this Question.
	* @return Difficulty of this Question.
	*/
	public DifficultyEnum getDifficulty()
	{
		return DifficultyEnum.getEnumFromCode(getDifficultyCode());
	}

	//-----------------------------
	// Create methods.
	//-----------------------------

	public Object ejbCreate( String name, String ques, Integer answer,
		String hint, DifficultyEnum difficulty,
		String explain, int timeLimitSecs ) throws CreateException
	{
		setId( UniqueIdGenerator.getInstance().createId(name) );
		setName(name);
		setContent(ques);
		setAnswer(answer);
		setHint(hint);
		setDifficultyCode(difficulty.getCode());
		// Just use the diffilcuty code as the score for this Question.
		setScore(difficulty.getCode().intValue());
		setExplanation( explain);
		setTestId("");
		setTimeLimitSeconds(timeLimitSecs);
		setActive(true);
		long nowMillis = System.currentTimeMillis();
		setCreatedMillis( nowMillis );
		setLastModifiedMillis(nowMillis);
		return null;
	}
	
	public void ejbPostCreate( String name, String ques, Integer answer,
		String hint, DifficultyEnum difficulty,
		String explain, int timeLimitSecs  )
	{ 
	}
	
	
}