设计模式之组合模式——Java语言描述
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2022-07-02 17:02:48
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 ......
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*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<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+" ]"); } }
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 ]
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