关于对聚合和组合的理解

来源：互联网发布：淘宝店铺转让价格编辑：程序博客网时间：2024/05/18 00:29

今天看了看

深入PHP++面向对象、模式与实践_第三版

其中看到“聚合”跟“组合”的概念，对此理解也比较模糊
文中是这样说的：

请输入图片描述

理解上面文本中的话，我个人理解是成这样：

首先是聚合

    <?php/** * Created by PhpStorm. * ClassName: AggregationA * User: JAN * Date: 14-9-12 * Time: 下午12:18 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Aggregation;class AggregationA{    protected $aggregation = array();    public function __construct()    {        array_push($this->aggregation, new AggregationB());        array_push($this->aggregation, new AggregationC());    }    public function addAggregation(AggregationInterface $aggregation)    {        array_push($this->aggregation, $aggregation);        return $this;    }    public function getAggregationList()    {        return $this->aggregation;    }}

    <?php/** * Created by PhpStorm. * ClassName: AggregationB * User: JAN * Date: 14-9-12 * Time: 下午12:18 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Aggregation;class AggregationB implements AggregationInterface{    public function getName()    {        return $this;    }}

    <?php/** * Created by PhpStorm. * ClassName: AggregationC * User: JAN * Date: 14-9-12 * Time: 下午2:34 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Aggregation;class AggregationC implements AggregationInterface{    public function getName()    {        return $this;    }}

    <?php/** * Created by PhpStorm. * ClassName: AggregationInterface * User: JAN * Date: 14-9-12 * Time: 下午2:38 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Aggregation;interface AggregationInterface{    public function getName();}

类内聚了两个类：分别是agregationB, agregationC 分别都实现了AgregationInterface, 而且在实力AgregationA的时候构造时实例化B和C。

再次是组合：

A类

    <?php/** * Created by PhpStorm. * ClassName: CompositionA * User: JAN * Date: 14-9-12 * Time: 下午12:25 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Composition;class CompositionA{    private $compositionB = null;    private $compositionC = null;    public function setCompositionB(CompositionB $compositionB)    {        $this->compositionB = $compositionB;        return $this;    }    public function getCompositionB()    {        return $this->compositionB;    }    public function setCompositionC(CompositionC $compositionC)    {        $this->compositionC = $compositionC;        return $this;    }    public function getCompositionC()    {        return $this->compositionC;    }}

B类

    <?php/** * Created by PhpStorm. * ClassName: CompositionB * User: JAN * Date: 14-9-12 * Time: 下午12:25 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Composition;class CompositionB implements CompositionObjectInterface{    public function getName()    {        return $this;    }}

C类

    <?php/** * Created by PhpStorm. * ClassName: CompositionC * User: JAN * Date: 14-9-12 * Time: 下午2:42 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Composition;class CompositionC implements CompositionObjectInterface{    public function getName()    {        return $this;    }}

接口

    <?php/** * Created by PhpStorm. * ClassName: CompositionObjectInterface * User: JAN * Date: 14-9-12 * Time: 下午12:29 * Link: http://blog.segmentfault.com/janhuang */namespace DesignPattern\SimpleExample\Composition;interface CompositionObjectInterface{    public function getName();}

在实例化CompositionA 的时候并不会直接实例化其他类，这里只是清楚限定了CompositionB类作为参数类型传入setCompotionB方法，这里理解的组合就是：有提供组合的方法提供外界指定的类进行自由组合，并且使用组合当中的方法。

以上仅是个人的理解，不知道这对类的关系有没有帮助，最近在学习设计模式，概念有点模糊，还请各路英雄指点。感谢

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