carfield.com.hk

CharacterFlyweight.java

2004-03-24T16:00:00Z

FlyweightImplementation.java

2004-03-24T16:00:00Z

package examples.flyweight.aspectj; 

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.patterns.
 *
 * Contributor(s): 
 */
 
import ca.ubc.cs.spl.pattern.library.FlyweightProtocol;

/**
 * Implements a concrete instance of the flyweight pattern. 
 *
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 */


public aspect FlyweightImplementation extends FlyweightProtocol {
	
 /** 
 * Assigns the Flyweight role to CharacterFlyweight.
 */

	declare parents: CharacterFlyweight	 implements Flyweight;

 /** 
 * Assigns the Flyweight role to WhitespaceFlyweight.
 */

	declare parents: WhitespaceFlyweight implements Flyweight;

 /**
 * Actually creates the flyweight for a key. This method is called by
 * <code>getFlyweight(Object)</code> if the flyweight does not already
 * exist.
 *
 * @param key the key identifying the particular flyweight
 * @returns the flyweight representing the key
 */

	protected Flyweight createFlyweight(Object key) {
		char c = ((Character) key).charValue(); 
		Flyweight flyweight = null;
		if (Character.isWhitespace(c)) {
			flyweight = new WhitespaceFlyweight(c);
		} else { 
			flyweight = new CharacterFlyweight(c);
		}
		return flyweight; 
	} 
	
 /**
 * Provides a custom interface to access the flyweights. Refers to the 
 * general <code>getFlyweight(Object)</code> method defined on the
 * abstract aspect.
 *
 * @param c the character identifying the particular flyweight
 * @returns the flyweight representing the character
 */

	public PrintableFlyweight getPrintableFlyweight(char c) {
		Character ch = new Character(c); 
		return (PrintableFlyweight) getFlyweight(ch);
	}
}

Main.java

2004-03-24T16:00:00Z

package examples.flyweight.java;

/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This file is part of the design patterns project at UBC
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is ca.ubc.cs.spl.patterns.
 *
 * Contributor(s): 
 */
 
/**
 * Implements the driver for the flyweight design pattern example. 
 *
 * Intent: Use sharing to support large numbers of fine-grained objects 
 * efficiently.
 *
 * Participating flyweight classes are <code>characterFlyweight</code>, and
 * <code>WhitespaceFlyweight</code>. Both implement the <code>
 * PrintableFlyweight</code> interface. Flyweights are generated via the 
 * <code>PrintableFlyweightFactory</code>. 
 * 
 * These are the pattern roles: <UL>
 *
 * <LI> CharacterFlyweightFactory: FlyweightFactory
 * <LI> PritableFlyweight: Flyweight
 * <LI> CharacterFlyweight:	ConcreteFlyweight
 * <LI> WhitespaceFlyweight: ConcreteFlyweight
 * <LI> Main: Client 
 * </UL> 
 *
 * Intrinsic state: The character to print, 
 * Extrinsic state: Whether the char is upper case or lower case
 
 *
 * This example creates a sentence out of <code>PrintableFlyweights
 * (characters and whitespaces).
 *
 * This is the Java version. 
 *
 * This implementation is analoguous to the books description.
 * For this version, we only use two classes for the flyweights,
 * CharacterFlyweight and WhitespaceFlyweight. Plus, this implementation
 * uses a better factory that keeps a hashtable of created Flyweights
 * and employs creation of demand.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 * @see PrintableFlyweight
 * @see PrintableFlyweightFactory
 */

public class Main {

 /**
 * Implements the driver for the flyweight design pattern example. 
 *
 * Intent: Use sharing to support large numbers of fine-grained objects 
 * efficiently.
 *
 * This example creates a sentence out of <code>PrintableFlyweights
 * (characters and whitespaces). 
 */

	public static void main(String[] args) {
	
		System.out.println("This is a test for the java Flyweight pattern "
		 + "implementation.");
		System.out.println("The client will use char flyweights to print the "
		 + "phrase");
		System.out.println("\"This Is A Test\".\n");
		System.out.println("Testing Pattern: Flyweight - STARTING\n");

		PrintableFlyweightFactory pff = new PrintableFlyweightFactory();
		
		PrintableFlyweight T = pff.getPrintableFlyweight('t');
		PrintableFlyweight H = pff.getPrintableFlyweight('h');
		PrintableFlyweight I = pff.getPrintableFlyweight('i');
		PrintableFlyweight S = pff.getPrintableFlyweight('s');
		PrintableFlyweight A = pff.getPrintableFlyweight('a');
		PrintableFlyweight E = pff.getPrintableFlyweight('e');
		PrintableFlyweight Empty = pff.getPrintableFlyweight(' '); 
		
		// Printing: "This Is A Test"
	
		T.print(true);
		H.print(false);
		I.print(false);
		S.print(false);
		
		Empty.print(true);
		
		I.print(true);
		S.print(false);
		
		Empty.print(true);
		
		A.print(true);
		
		Empty.print(true);
		
		T.print(true);
		E.print(false);
		S.print(false);
		T.print(false);	
		
		System.out.println();
		
		System.out.println("\nTesting Pattern: State - FINISHED");
	}
}

PrintableFlyweight.java

2004-03-24T16:00:00Z

PrintableFlyweightFactory.java

2004-03-24T16:00:00Z

WhitespaceFlyweight.java

2004-03-24T16:00:00Z

files.lst

2004-03-24T16:00:00Z