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设计模式——组合模式（Composite Pattern）+ Spring相关源码

news 2025/8/28 15:36:01

文章目录

一、组合模式定义
二、例子
- 2.1 菜鸟教程例子
- - 2.1.1 创建 Employee 类，该类带有 Employee 对象的列表。
  - 2.1.2 使用 Employee 类来创建和打印员工的层次结构。
- 2.2 JDK源码——java.awt.Container
- 2.3 Spring源码——CompositeCacheManager
三、其他设计模式

一、组合模式定义

类型： 结构型模式
介绍： 一种树形结构。它又叫部分整体模式，是用于把一组相似的对象当作一个单一的对象。
目的： 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。

二、例子

2.1 菜鸟教程例子

2.1.1 创建 Employee 类，该类带有 Employee 对象的列表。

public class Employee {private String name;private String dept;private int salary;private List<Employee> 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<Employee>();}public void add(Employee e) {subordinates.add(e);}public void remove(Employee e) {subordinates.remove(e);}public List<Employee> getSubordinates(){return subordinates;}public String toString(){return ("Employee :[ Name : "+ name +", dept : "+ dept + ", salary :"+ salary+" ]");}   
}

2.1.2 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);}}        }
}

2.2 JDK源码——java.awt.Container

public class Container extends Component {private java.util.List<Component> component = new ArrayList<>();public Component getComponent(int n) {try {return component.get(n);} catch (IndexOutOfBoundsException z) {throw new ArrayIndexOutOfBoundsException("No such child: " + n);}}public Component add(Component comp) {addImpl(comp, null, -1);return comp;}}

2.3 Spring源码——CompositeCacheManager

public class CompositeCacheManager implements CacheManager, InitializingBean {private final List<CacheManager> cacheManagers = new ArrayList();@Nullablepublic Cache getCache(String name) {Iterator var2 = this.cacheManagers.iterator();Cache cache;do {if (!var2.hasNext()) {return null;}CacheManager cacheManager = (CacheManager)var2.next();cache = cacheManager.getCache(name);} while(cache == null);return cache;}
}