carfield.com.hk

AnotherRealSubject.java

2004-03-24T16:00:00Z

DelegationProxy.java

2004-03-24T16:00:00Z

package examples.proxy.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.ProxyProtocol;
import org.aspectj.lang.JoinPoint;

/**
 * Implements a concrete proxy pattern instance. Here, all method calls from 
 * <code>Main</code> to <code>RealSubject.print(String)</code> are blocked. 
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 */ 
 
public aspect DelegationProxy extends ProxyProtocol { 
 
 /** 
 * Assigns the Subject role to <code>RealSubject</code>.
 */
 
 declare parents: RealSubject implements Subject;

 /**
 * Captures all accesses to the subject that should be protected by 
 * this pattern instance. Here: All calls to <code>RealSubject.write(..)
 * </code>.
 */

	protected pointcut protectedAccess(): call(* RealSubject.write(..));


	/**
	 * Checks whether the access should be denied or not. Here: All accesses
	 * matched by the <code>protectedAccesses()</code> joinpoint.
	 *
 * @param caller the object responsible for the protected access
 * @param subject the subject receiving the call 
 * @param joinPoint the joinpoint associated with the protected access
 *
 * @returns true 
 */

	protected boolean rejection(Object caller, 
	 Subject subject, 
	 JoinPoint joinPoint) {
	 System.out.println("[DelegationProxy] delegating a write() call to "
	 +"AnotherRealSubject"); 
		return true;
	}

	/**
	 * For delegation: Provides an alternative return value if access 
	 * is denied. Here, it also calls an appropriate method on a delegate 
	 * (to illustrate how delegation works).
	 *
 * @param caller the object responsible for the protected access
 * @param subject the subject receiving the call 
 * @param joinPoint the joinpoint associated with the protected access
 *
 * @returns null
 */

	protected Object handleFailedAccess(Object caller, 
	 Subject subject, 
	 JoinPoint joinPoint) {
	 Object[] args = joinPoint.getArgs();
	 if (args != null) {
	 AnotherRealSubject.write((String)args[0]);
	 } else {
	 AnotherRealSubject.write("");
	 }
	 return null;
	}
}

Main.java

2004-03-24T16:00:00Z

package examples.proxy.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 proxy design pattern example. 
 *
 * Intent: Provide a surrogate or placeholder for another object to control
 * access to it.
 *
 * Participatng objects are <code>RealSubject</code>s and <code>Proxy</code>. 
 * Both implement the <code>Subject</code> interface.
 *
 * Proxy forwards or blocks requests to RealSubject
 *
 * This is the Java version. 
 *
 * <code>Proxy</code> needs to implement all methods of Subject, even 
 * those it is not interested in. Proxy needs to be aware of its role
 * in the pattern.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 * @see Subject
 * @see RealSubject
 * @see Proxy
 */

public class Main { 

 /**
 * Implements the driver for the proxy design pattern. Experimental setup:
 * The proxy is to count the number of calls to RealSubject.print(String). 
 * It is not interested in calls to Subject.write(String).
 * Proxy has to implement all method of subject, even those that are of 
 * no interest.
 */

	public static void main (String[] args) { 
		Subject real = new RealSubject();
		Subject proxy = new Proxy(real);
		
		proxy.print("PRINT");
		proxy.write("WRITE");
		proxy.print("PRINT");
		proxy.write("WRITE");
	}
}

ProtectionProxy.java

2004-03-24T16:00:00Z

package examples.proxy.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.ProxyProtocol;
import org.aspectj.lang.JoinPoint;

/**
 * Implements a concrete proxy pattern instance. Here, all method calls from 
 * <code>Main</code> to <code>RealSubject.print(String)</code> are blocked. 
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 */ 

public aspect ProtectionProxy extends ProxyProtocol { 
 
 /** 
 * Assigns the Subject role to <code>RealSubject</code>.
 */
 
 declare parents: RealSubject implements Subject;

 /**
 * Captures all accesses to the subject that should be protected by 
 * this pattern instance. Here: All calls to <code>RealSubject.print(..)
 * </code>.
 */

	protected pointcut protectedAccess(): call(* RealSubject.print(..));

	/**
	 * Checks whether the access should be denied or not. Here: All accesses
	 * that come from <code>Main</code> objects are denied.
	 *
 * @param caller the object responsible for the protected access
 * @param subject the subject receiving the call 
 * @param joinPoint the joinpoint associated with the protected access
 *
 * @returns true if the access is from a Main object, false otherwise
 */

	protected boolean rejection(Object caller, 
	 Subject subject, 
	 JoinPoint joinPoint) { 
		if (joinPoint.getThis() instanceof Main) {
			System.out.println("[MyRejecting:] Intercepting calls to "
			 +"RealSubject.print() from Main");
			return true;
		} else {
			return false;
		}
	}

	/**
	 * For delegation: Provides an alternative return value if access 
	 * is denied.
	 *
 * @param caller the object responsible for the protected access
 * @param subject the subject receiving the call 
 * @param joinPoint the joinpoint associated with the protected access
 *
 * @returns null
 */

	protected Object handleFailedAccess(Object caller, 
	 Subject subject, 
	 JoinPoint joinPoint) {
	 return null;
	}
}

Proxy.java

2004-03-24T16:00:00Z

package examples.proxy.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 a Proxy according to GoF. It implements the
 * Subject interface as RealSubject does.
 *
 * @author Jan Hannemann
 * @author Gregor Kiczales
 * @version 1.0, 05/13/02
 * 
 * @see Subject
 * @see Proxy
 */ 

public class Proxy implements Subject { 
 
 /**
 * a reference to the RealSubject for method forwarding
 */
 
	private Subject realSubject; 
	
	/**
	 * An internal counter for the number of calls to <code>
	 * print(String)</code>.
	 */
	 
	private int printCalls = 0;
	
 /**
 * Creates a new Proxy with the given RealSubject.
 *
 * @param subject The RealSubject to forward method calls to
 */

	public Proxy(Subject subject) {
		this.realSubject = subject;
	}
	
 /**
 * Prints the argument string to <code>System.out</code>. This is 
 * equivalent to <code>write(String)</code>
 *
 * @param s the string to print
 */
 
	public void print(String s) {
		printCalls++;
		realSubject.print(s); 
		System.out.println("[Proxy:] That was call "+printCalls+" to Subject.print(String)");		
	}
	
 /**
 * Prints the argument string to <code>System.out</code>. This is 
 * equivalent to <code>print(String)</code>
 *
 * @param s the string to print
 */

	public void write(String s) {
		realSubject.write(s); 
		System.out.println("[Proxy:] Not interested in write calls, but must implement anyway");		
	}
	
}

RealSubject.java

2004-03-24T16:00:00Z

Subject.java

2004-03-24T16:00:00Z

files.lst

2004-03-24T16:00:00Z