Java 裝飾模式 （Decorator）

裝飾模式

動態的將責任附加到對象上。若要擴展功能，裝飾者提供了比繼承更有彈性的取代方案

代碼

package gx.component;

/** * 組件：裝飾類和被裝飾類 都要繼承：爲了類型保持一致 * @author always * */
public abstract class Component {

    public abstract void description();
    public abstract int cost();
}

package gx.component.impl;

import gx.component.Component;


/** * 裝飾類的抽象類 * @author always * */
public abstract class Decorator extends Component{

    protected Component component;
}

package gx.component.impl;

import gx.component.Component;

/** * * 被包裝的類 * @author always * */
public class Phone extends Component{

    public void description() {
        System.out.println("裸機");
    }

    public int cost() {

        return 1900;
    }


}

package gx.decorator.impl;

import gx.component.Component;
import gx.component.impl.Decorator;

/** * * 裝飾1：給手機買個殼 * @author always * */
public class DaiKe extends Decorator{

    public DaiKe(){

    }

    public DaiKe(Component component){
        this.component=component;
    }
    public void description() {
        this.component.description();
        System.out.println("帶了手機殼");
    }

    public int cost() {
        return 50+this.component.cost();
    }

}

package gx.decorator.impl;

import gx.component.Component;
import gx.component.impl.Decorator;

/** * * 裝飾2：給手機貼個膜 * @author always * */
public class TieMo extends Decorator{

    public TieMo(){}

    public TieMo(Component component){
        this.component=component;
    }

    public void description() {
        this.component.description();
        System.out.println("貼了膜");
    }

    public int cost() {
        return 20+this.component.cost();
    }

}

測試類：

package gx;

import gx.component.Component;
import gx.component.impl.Phone;
import gx.decorator.impl.DaiKe;
import gx.decorator.impl.TieMo;
import junit.framework.TestCase;

public class TestDecorator extends TestCase {

    public void testDecorator() {

        Component component = new TieMo(new DaiKe(new Phone()));

        component.description();
        System.out.println("價錢：" + component.cost());
        /* * 結果： * 裸機 * 帶了手機殼 * 貼了膜 * 價錢：1970 */
    }
}