设计模式开始--组合模式

组合模式

一、作用

需求是体现部分与整体的关系时，完成的功能就是基础的对象可以组成成更加复杂的对象，而这个组合的对象又可以进一步的组合，不断的迭代，便可以体现出层次的结构

二、类图（核心在于有一个之类有一个向上的引用）

三、实现

（1）Company定义结构

public abstract class Company {
    protected String name;
    public Company(String name)
    {
        this.name = name;
    }
    public Company(){}
    public abstract void add(Company company);
    public abstract void remove(Company company);
    public abstract void display();
}

（2）具体Company实现类

public class HRCompany extends Company {
    public HRCompany(String name)
    {
        this.name = name;
    }
    @Override
    public void add(Company company) {
    }
    @Override
    public void remove(Company company) {
    }
    @Override
    public void display() {
        System.out.println(name);
    }
}
public class BeiJCompany extends Company {
    private List<Company> list = new ArrayList<Company>();
    public BeiJCompany(String name)
    {
        this.name = name;
    }
    @Override
    public void add(Company company) {
        list.add(company);
    }
    @Override
    public void remove(Company company) {
        list.remove(company);
    }
    @Override
    public void display() {
        System.out.println(name);
        for(Company company: list)
        {
            System.out.print("\t");
            company.display();
        }
    }
}

（3）Client测试类

public class Client {
    public static void main(String[] args)
    {
        Company root = new HRCompany("总部HR");
        Company beijingHr = new HRCompany("北京总部HR");
        Company beijing = new BeiJCompany("北京分部");
        beijing.add(beijingHr);
        root.display();
        beijing.display();
    }
}