设计模式笔记——Decorator

 装饰模式Decorator

动态地给一个对象增加额外的职责，就增加功能来说，装饰模式比生成子类更灵活。

 

装饰模式视为已经有的功能动态地添加多更多的功能的一种方式。它把要装饰的功能单独封装在一个类里面，并让这个类封装它要装饰的对象，这样就可以为原有的对象增加新的功能，从而不会因为功能的扩展增加了竹类的复杂度。当需要执行特殊行为时，用户可以选择的使用装饰功能包含的对象。

 

有效的把类的核心职责和装饰功能分开，除掉了类中重复的装饰修饰。

package decorator.pattern;

public class DecoratorPattern {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		ConcreteCompoment compoment=new ConcreteCompoment();
		ConcreteDecoratorA decoratorA=new ConcreteDecoratorA();
		ConcreteDecoratorB decoratorB=new ConcreteDecoratorB();
		
		decoratorA.SetCompoment(compoment);
		decoratorB.SetCompoment(decoratorA);
		
		decoratorB.Operation();
	}

}

package decorator.pattern;

public interface Compoment {

	public void Operation();
}

package decorator.pattern;

public class ConcreteCompoment implements Compoment {

	@Override
	public void Operation() {
		// TODO Auto-generated method stub
		System.out.println("Concrete Compoment Operation");
	}

}

package decorator.pattern;

public class Decorator implements Compoment {

	protected Compoment compoment;

	public void SetCompoment(Compoment compoment) {
		this.compoment = compoment;
	}

	@Override
	public void Operation() {
		// TODO Auto-generated method stub
		if (compoment != null)
			compoment.Operation();
	}

}

package decorator.pattern;

public class ConcreteDecoratorB extends Decorator {

	private String state;

	@Override
	public void Operation() {
		// TODO Auto-generated method stub
		super.Operation();
		setState("stateB");
		System.out.println("ConcreteDecoratorB Operation");
	}

	private void setState(String state) {
		this.state = state;
	}

	public String getState() {
		return state;
	}
	
	
}

package decorator.pattern;

public class ConcreteDecoratorA extends Decorator {

	private String state;

	@Override
	public void Operation() {
		// TODO Auto-generated method stub
		super.Operation();
		setState("stateA");
		System.out.println("ConcreteDecoratorA Operation");
	}

	private void setState(String state) {
		this.state = state;
	}

	public String getState() {
		return state;
	}
	
	
}