구조패턴 : Bridge 패턴

분류 : 구조패턴(Structural Patterns)

정의 :

추상화를 구현에서 분리해서 서로 독립적으로 만드는 패턴.

용도 :

Abstraction : 추상 인터페이스를 정의. Implementor 참조를 관리

RefinedAbstraction : Abstraction에서 정의된 인터페이스를 확장함.

Implementor : 구현클래스를 위한 인터페이스를 정의함.

ConcreteImplementor : Implementor 인터페이스를 구현함.

소스

// Implementor
public interface DrawingAPI {
	public void drawCircle(double x, double y, double radius);
}


//ConcreteImplementor 첫번째
public class DrawingAPI1 implements DrawingAPI {

	@Override
	public void drawCircle(double x, double y, double radius) {
		System.out.printf("API1.circle at %f:%f radius %f\n", x, y, radius);
	}

}


//ConcreteImplementor 두번째
public class DrawingAPI2 implements DrawingAPI {

	@Override
	public void drawCircle(double x, double y, double radius) {
		System.out.printf("API2.circle at %f:%f radius %f\n", x, y, radius);
	}

}


//Abstraction
public abstract class Shape {
	protected DrawingAPI drawingAPI;
	 
   protected Shape(DrawingAPI drawingAPI){
      this.drawingAPI = drawingAPI;
   }
	 
   public abstract void draw();                             // 저수준
   public abstract void resizeByPercentage(double pct);     // 고수준
}


//Refined Abstraction
public class CircleShape extends Shape {

	private double x, y, radius;
	
	public CircleShape(double x, double y, double radius, DrawingAPI drawingAPI) {
      super(drawingAPI);
      this.x = x;  this.y = y;  this.radius = radius;
   }
	
	//저수준, 즉 Implementation 명시
	@Override
	public void draw() {
		// TODO Auto-generated method stub
		drawingAPI.drawCircle(x, y, radius);
	}

	//고수준, Abstraction 명시
	@Override
	public void resizeByPercentage(double pct) {
		// TODO Auto-generated method stub
		radius *= pct;
	}

}

//Client
public class BridgePattern {

	public static void main(String[] args) {
		Shape[] shapes = new Shape[] {
				new CircleShape(1, 2, 3, new DrawingAPI1()),
				new CircleShape(5, 7, 11, new DrawingAPI2()),
		};
	 
		for (Shape shape : shapes) {
			shape.resizeByPercentage(2.5);
			shape.draw();
		}
   }

}

참고자료

http://en.wikipedia.org/wiki/Bridge_pattern