Composite(组合)模式.doc

设计模式-Composite(组合)模式GoF：将对象组合合成树形结构以表示“部分-整体”的层次结构。Composite使得用户对单个对象和组合对象的使用具有一致性。组合体内这些对象都有共同接口,当组合体一个对象的方法被调用执行时，Composite将遍历(Iterator)整个树形结构,寻找同样包含这个方法的对象并实现调用执行。可以用牵一动百来形容。Composite模式描述了并实现了树形目录结构，在该模式中要有一个组合体，它是一个抽象类或接口（Component），组合体中定义足够多的方法。当组合体（Component）一个对象的方法被调用执行时，Composite将遍历（Iterator）整个树形结构，寻找同样包含这个方法的对象并实现调用执行。在Composite模式中要用到Iterator（迭代器）模式和Chain of Responsibility(职责链)模式。这两个模式我还没有学到，但是Java中的Iterator我用过。暂时先将Composite模式实现。以组装电脑为例，首先需要一个组合体：package Composite;import java.util.Iterator;public abstract class EquipmentComponent String E_name; public String getName() return E_name; /end getName(.) public void setName(String strName) this.E_name = strName; /end setName(.) public double getPrice(int eNumber, double price) double equipmentPrice = 0; equipmentPrice = eNumber * price; return equipmentPrice; /end getPrice() public abstract double equipmentPrice(int eNumber, double price); public boolean add(EquipmentComponent eq) return false; /end add(.) public boolean remove(EquipmentComponent eq) return false; /end remove(.) public Iterator iter() return null; /end iter()/end abstract class EquipmentComponent接着我们实现一个软盘的类：package Composite;public class FloppyDisk extends EquipmentComponent public FloppyDisk() /do something. /end FloppyDisk() public double equipmentPrice(int eNumber, double price) double equipmentPrice = getPrice(eNumber, price); return equipmentPrice; /end equipmentPrice() /end class FloppyDisk下面实现Composite类：package Composite;import java.util.ArrayList;import java.util.Iterator;public class EquipmentComposite extends EquipmentComponent /* Creates a new instance of EquipmentComposite */ public EquipmentComposite() /do something. /end EquipmentComposite() private ArrayList equipment = new ArrayList(); public double equipmentPrice(int eNumber, double price) double equipmentPrice = 0; Iterator eIter = equipment.iterator(); while(eIter.hasNext() equipmentPrice += (EquipmentComponent)eIter.next().getPrice(eNumber, price); return equipmentPrice; /end equipmentPrice(.) public boolean add(EquipmentComponent eqc) boolean addBool = equipment.add(eqc); if (addBool) return true; else return false; /end add(.) public boolean remove(EquipmentComponent eqc) if(equipment.size() = 0) return false; boolean removeBool = equipment.remove(eqc); if(removeBool) return true; else return false; /end remove(.) /end class EquipmentComposite接着实现一个箱子类：package Composite;public class Cabinet extends EquipmentComposite public Cabinet() /do something. /end Mosue() public double equipmentPrice(int eNumber, double price) double chassisPrice = super.equipmentPrice(eNumber, price); return chassisPrice; /end equipmentPrice(.) /class Cabinet最后看看调用：/* * CompositePattern.java * * Created on 2006年3月30日, 上午11:14 * * To change this template, choose Tools | Template Manager * and open the template in the editor. */package Composite;/* * * author Administrator */public class CompositePattern Cabinet chassis = new Cabinet(); /* * Creates a new instance of CompositePattern */ public CompositePattern() /do something. /end CompositePattern() public void showCompositePattern() chassis.setName(Power); String chassisName = chassis.getName(); chassis.add(new FloppyDisk(); double chassisPrice = chassis.equipmentPrice(1, 32.5); System.out.println(The chassis name is: + chassisName); System.out.println(The chassis price is: + chassisPrice); /end showCompositePattern() public static void main(String args) System.out.println(*-*); System.out.println(The Composite Pattern!); CompositePattern cp = new CompositePattern(); cp.showCompositePattern(); System.out.println(*-*); /end main(.) /end class CompositePattern下面是Composite模式的UML图：其中：EquipmentComponent，为组合中的对象声明接口；在适当情况下实现所有类共有接口的缺省行为。FloppyDisk，在组合中表示叶结点对象，叶结点没有子结点。EquipmentComposite，定义有子部件的那些行为；存储子部件。Chassis，子部件，用于存储叶结点。在上例的代