装饰者模式后续理解消化中

/**
 * 
 */
package decorator2;

/**
 * @author wangjian2
 *
 */
public interface InterfaceComponent {
    public void say();
}

package decorator2;

public class Component implements InterfaceComponent {

    @Override
    public void say() {
        System.out.println("Component.say():原组件的方法！");
    }

}

package decorator2;

public abstract class AbstractDecorator implements InterfaceComponent {

    private InterfaceComponent component;

    public AbstractDecorator(InterfaceComponent component) {
        this.component = component;
    }

    /**
     * 组件方法执行前预处理方法
     * 
     */
    protected void preSay() {
    };

    /**
     * 组件方法执行后处理方法
     * 
     */
    protected void afterSay() {
    };

    public void say() {

        preSay();
        component.say();
        afterSay();

    };
}

package decorator2;

public class DecoratorTwo extends AbstractDecorator {

    public DecoratorTwo(InterfaceComponent component) {
        super(component);
        // TODO 自动生成构造函数存根
    }

    /**
     * 根据需要重载模板类preSay()方法
     */
    protected void preSay() {
        System.out.println("DecoratorTwo.preSay():装饰者二的preSay()方法！");
    }

    /**
     * 根据需要重载模板类afterSay()方法
     */
    protected void afterSay() {
        System.out.println("DecoratorTwo.afterSay():装饰者二的afterSay()方法！");
    }

}

package decorator2;

public class DecoratorOne extends AbstractDecorator {

    public DecoratorOne(InterfaceComponent component) {
        super(component);
        // TODO 自动生成构造函数存根
    }

    /**
     * 根据需要重载模板类preSay()方法
     */
    protected void preSay() {
        System.out.println("DecoratorOne.preSay():装饰者一的preSay()方法！");
    }

    /**
     * 根据需要重载模板类afterSay()方法
     */
    protected void afterSay() {
        System.out.println("DecoratorOne.afterSay():装饰者一的afterSay()方法！");
    }

    /**
     * 测试方法
     * 
     * @param args
     */
    public static void main(String[] args) {
        // TODO 自动生成方法存根
        InterfaceComponent interfaceComponent = new DecoratorTwo(
                new DecoratorOne(new Component()));
        interfaceComponent.say();
        /*
         * 控制台输出： DecoratorTwo.preSay():装饰者二的preSay()方法！
         * DecoratorOne.preSay():装饰者一的preSay()方法！ Component.say():原组件的方法！
         * DecoratorOne.afterSay():装饰者一的afterSay()方法！
         * DecoratorTwo.afterSay():装饰者二的afterSay()方法！
         */
    }
}

执行顺序：

interfaceComponent.say()=》DecoratorTwo继承AbstractDecorator的say()方法，并执行该方法=》执行DecoratorTwo的preSay方法=》
DecoratorTwo的构造方法的参数component是DecoratorOne，所以执行DecoratorOne的say方法=》
执行DecoratorOne的preSay方法=》执行Component类的say()方法=》执行DecoratorOne的afterSay方法=》
执行DecoratorTwo的afterSay方法
输出结果：

DecoratorTwo.preSay():装饰者二的preSay()方法！
DecoratorOne.preSay():装饰者一的preSay()方法！
Component.say():原组件的方法！
DecoratorOne.afterSay():装饰者一的afterSay()方法！
DecoratorTwo.afterSay():装饰者二的afterSay()方法！

二、另一种装饰者模式代码

/**
 * 
 */
package decorator3;

/**
 * @author wangjian2
 *
 */
public interface Component {
    
    public double price();
}

/**
 * 
 */
package decorator3;

/**
 * @author wangjian2
 *
 */
public class AllNeedMilk implements Component {
    private double price = 10.5;

    @Override
    public double price() {
        // TODO Auto-generated method stub
        return this.price;
    }

}

/**
 * 
 */
package decorator3;

/**
 * @author wangjian2
 *
 */
public abstract class Fruit implements Component {
    private Component component;
    
    public Fruit(Component component) {
        this.component = component;
    }
    
    protected double newPrice() {
        return 0;
    }
    
    public double price(){
        return newPrice()+component.price();
    }
}

/**
 * 
 */
package decorator3;

/**
 * @author wangjian2
 *
 */
public class Apple extends Fruit {

    public Apple(Component component) {
        super(component);
        // TODO Auto-generated constructor stub
    }
    
    protected double newPrice() {
        return 20;
    }

}

/**
 * 
 */
package decorator3;

/**
 * @author wangjian2
 *
 */
public class Orange extends Fruit {

    public Orange(Component component) {
        super(component);
        // TODO Auto-generated constructor stub
    }
    
    protected double newPrice() {
        return 30;
    }

}

/**
 * 
 */
package decorator3;

/**
 * @author wangjian2
 *
 */
public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Component apple = new Apple(new Orange(new AllNeedMilk()));
        System.out.println(apple.price());
        Component orange = new Orange(new AllNeedMilk());
        System.out.println(orange.price());
    }

}

输出结果：

60.5
40.5