设计模式之组合模式——Java语言描述-白红宇

设计模式之组合模式——Java语言描述

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发布时间：2019-06-13

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组合模式又叫做部分整体模式，适用于把一组相似的对象当作一个单一的对象。组合模式依据树形结构来组合对象，用来表示部分以及整体层次

介绍

意图

将对象组合成树形结构以表示“部分-整体”的层次结构。组合模式使得用户对单个对象和组合对象的使用具有一致性

优点

高层模块调用简单

节点自由增加

缺点

在使用组合模式时，其叶子和树枝的声明都是实现类，而不是接口类，违反了依赖导致的原则

实现

创建一个Employee类，使用该类作为组合模型。

创建Employee类，该类带有Employee对象的列表

import java.util.ArrayList;import java.util.List; public class Employee {   private String name;   private String dept;   private int salary;   private List
    
      subordinates;    //构造函数   public Employee(String name,String dept, int sal) {      this.name = name;      this.dept = dept;      this.salary = sal;      subordinates = new ArrayList
     
      ();   }    public void add(Employee e) {      subordinates.add(e);   }    public void remove(Employee e) {      subordinates.remove(e);   }    public List
      
        getSubordinates(){     return subordinates;   }    public String toString(){      return ("Employee :[ Name : "+ name       +", dept : "+ dept + ", salary :"      + salary+" ]");   }   }

使用 Employee 类来创建和打印员工的层次结构

public class CompositePatternDemo {   public static void main(String[] args) {      Employee CEO = new Employee("John","CEO", 30000);       Employee headSales = new Employee("Robert","Head Sales", 20000);       Employee headMarketing = new Employee("Michel","Head Marketing", 20000);       Employee clerk1 = new Employee("Laura","Marketing", 10000);      Employee clerk2 = new Employee("Bob","Marketing", 10000);       Employee salesExecutive1 = new Employee("Richard","Sales", 10000);      Employee salesExecutive2 = new Employee("Rob","Sales", 10000);       CEO.add(headSales);      CEO.add(headMarketing);       headSales.add(salesExecutive1);      headSales.add(salesExecutive2);       headMarketing.add(clerk1);      headMarketing.add(clerk2);       //打印该组织的所有员工      System.out.println(CEO);       for (Employee headEmployee : CEO.getSubordinates()) {         System.out.println(headEmployee);         for (Employee employee : headEmployee.getSubordinates()) {            System.out.println(employee);         }      }           }}

输出结果

Employee :[ Name : John, dept : CEO, salary :30000 ]Employee :[ Name : Robert, dept : Head Sales, salary :20000 ]Employee :[ Name : Richard, dept : Sales, salary :10000 ]Employee :[ Name : Rob, dept : Sales, salary :10000 ]Employee :[ Name : Michel, dept : Head Marketing, salary :20000 ]Employee :[ Name : Laura, dept : Marketing, salary :10000 ]Employee :[ Name : Bob, dept : Marketing, salary :10000 ]

转载于:https://www.cnblogs.com/AmosH/p/10254200.html

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