设计模式（组合模式）

组合模式是为了解决业务中“局部-整体”的关系，这里的局部整体互相嵌套，且具备相同的处理接口。

典型的角色是两个：

• component:包含自身抽象列表的类，下例中为Employee;
• composite：各个组成部分对外暴露的处理接口，下例中为toString，为单独抽象；

代码如下：

• Employee

package com.example;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Employee {

    private String name;
    private String deptname;
    private List<Employee> subs;

    public Employee(String name, String deptname){
        this.name = name;
        this.deptname = deptname;
        subs = new ArrayList<Employee>();
    }

    public void add(Employee e) {
        subs.add(e);
    }

    public void remove(Employee e) {
        for (Iterator<Employee> it = subs.iterator(); it.hasNext();) {
            if (((Employee) it.next()).name == e.name) {
                it.remove();
            }
        }
    }

    //这里的toString，等价于于composite方法
    public String toString() {
        return ("Employee :[ Name : " + name + ", dept : " + deptname + " ]");
    }

    public List<Employee> getSubs() {
        return subs;
    }

}

• App 测试类

public class App {

    public static void main(String[] args) {
        Employee e1 = new Employee("fredric", "dept1");
        Employee e2 = new Employee("sinny", "dept2");
        Employee e3 = new Employee("baobao", "dept2");
        e1.add(e2);
        e1.add(e3);
        for(Employee emp:e1.getSubs()){
            System.out.println(emp);
        }
        e1.remove(e2);
        for(Employee emp:e1.getSubs()){
            System.out.println(emp);
        }
    }
}