《大话设计模式》Java代码示例（十五）之组合模式

组合模式（Composite）：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。

package composite;

/**
 * 组合模式(Composite)
 * 公司抽象类
 */
public abstract class Company {

    protected String name;

    public Company(String name) {
        this.name = name;
    }

    public abstract void add(Company company);// 增加
    public abstract void remove(Company company);// 移除
    public abstract void display(int depth);// 显示
    public abstract void lineOfDuty();// 职责

}

package composite;

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

/**
 * 组合模式(Composite)
 * 具体公司类
 */
public class ConcreteCompany extends Company {

    private List<Company> children = new ArrayList<>();

    public ConcreteCompany(String name) {
        super(name);
    }

    @Override
    public void add(Company company) {
        children.add(company);
    }

    @Override
    public void remove(Company company) {
        children.remove(company);
    }

    @Override
    public void display(int depth) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            sb.append("-");
        }
        System.out.println(sb + name);
        for (Company c : children) {
            c.display(depth + 2);
        }
    }

    @Override
    public void lineOfDuty() {
        for (Company c : children) {
            c.lineOfDuty();
        }
    }
}

package composite;

import com.sun.xml.internal.ws.util.StringUtils;

/**
 * 组合模式(Composite)
 * 人力资源部
 */
public class HRDepartment extends Company {

    public HRDepartment(String name) {
        super(name);
    }

    @Override
    public void add(Company company) {
        // None
    }

    @Override
    public void remove(Company company) {
        // None
    }

    @Override
    public void display(int depth) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            sb.append("-");
        }
        System.out.println(sb + name);
    }

    @Override
    public void lineOfDuty() {
        System.out.println(name + " 员工招聘管理培训");
    }

}

package composite;

/**
 * 组合模式(Composite)
 * 财务部
 */
public class FinanceDepartment extends Company {

    public FinanceDepartment(String name) {
        super(name);
    }

    @Override
    public void add(Company company) {
        // None
    }

    @Override
    public void remove(Company company) {
        // None
    }

    @Override
    public void display(int depth) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < depth; i++) {
            sb.append("-");
        }
        System.out.println(sb + name);
    }

    @Override
    public void lineOfDuty() {
        System.out.println(name + " 公司财务收支管理");
    }

}

package composite;

/**
 * 组合模式(Composite)
 * 客户端main方法
 */
public class Client {

    public static void main(String[] args) {
        ConcreteCompany root = new ConcreteCompany("北京总公司");
        root.add(new HRDepartment("总公司人力资源部"));
        root.add(new FinanceDepartment("总公司财务部"));

        ConcreteCompany company = new ConcreteCompany("上海华东分公司");
        company.add(new HRDepartment("华东分公司人力资源部"));
        company.add(new FinanceDepartment("华东分公司财务部"));
        root.add(company);

        ConcreteCompany company1 = new ConcreteCompany("南京办事处");
        company1.add(new HRDepartment("南京办事处人力资源部"));
        company1.add(new FinanceDepartment("南京办事处财务部"));
        company.add(company1);

        ConcreteCompany company2 = new ConcreteCompany("杭州办事处");
        company2.add(new HRDepartment("杭州办事处人力资源部"));
        company2.add(new FinanceDepartment("杭州办事处财务部"));
        company.add(company2);

        System.out.println("结构图：");
        root.display(1);

        System.out.println("职责：");
        root.lineOfDuty();
    }

}