実装 - その 1

public interface Handler {
	public void handleRequest();
}

public class ConcreteHandlerA implements Handler {
	public void handleRequest() {
		System.out.println("ConcreteHandlerA.handleRequest()");
	}
}

public class ConcreteHandlerB implements Handler {
	public void handleRequest() {
		System.out.println("ConcreteHandlerB.handleRequest()");
	}
}

public class ConcreteHandlerC implements Handler {
	public void handleRequest() {
		System.out.println("ConcreteHandlerC.handleRequest()");
	}
}

public aspect Connector pertarget( target(Handler) ) {

	private Handler successor;

	public void connect(Handler successor) {
		this.successor = successor;
	}

	void around() : call( void Handler.handleRequest() ) {
		if (successor != null) {
			successor.handleRequest();
		} else {
			proceed();
		}
	}
}

public class Client {

	public static void main(String[] args) {

		ConcreteHandlerA handlerA = new ConcreteHandlerA();
		ConcreteHandlerB handlerB = new ConcreteHandlerB();
		ConcreteHandlerC handlerC = new ConcreteHandlerC();

		handlerA.handleRequest();
		handlerB.handleRequest();
		handlerC.handleRequest();


		Connector.aspectOf(handlerA).connect(handlerB);

		handlerA.handleRequest();


		Connector.aspectOf(handlerB).connect(handlerC);

		handlerA.handleRequest();
	}
}

実行結果:

ConcreteHandlerA.handleRequest()
ConcreteHandlerB.handleRequest()
ConcreteHandlerC.handleRequest()
ConcreteHandlerB.handleRequest()
ConcreteHandlerC.handleRequest()

参考文献とリソース

更新履歴

• 2003.11.26 : 執筆開始。

todo

• これでちゃんと Chain of Responsibility になってんの？
• MixJuice との関係