组合模式

将对象组合成树形结构以表示”部分-整体”的层次结构.
使用户对单个对象和组合对象的使用具有一致性.
组合模式定义了包含基本对象和组合对象的类层次结构.基本对象可以被组合成更复杂的组合对象,而这个组合对象又可以被组合,这样不断的递归下去,客户代码中,任何用到基本对象的地方都可以使用组合对象.
用户不用关心到底是处理一个叶节点还是处理一个组合结点,也就用不着为定义组合而写一些选择判断语句了.简单说就是组合模式让客户可以一致性的使用组合结构和单个对象.

package composite;

/**
 * Created by hero on 17-2-19.
 */
public abstract class Company {
    private String name;

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public abstract void add(Company c);
    public abstract void remove(Company c);
    public abstract void display(int depth);
    public abstract void lineOfDuty();    //履行职责
}

package composite;

import java.util.LinkedList;
import java.util.List;

/**
 * Created by hero on 17-2-19.
 */
public class ConcreteCompany extends Company {
    private List<Company> children;

    public ConcreteCompany(String name) {
        super(name);
        children = new LinkedList<Company>();
    }

    public void add(Company c) {
        children.add(c);
    }

    public void remove(Company c) {
        children.remove(c);
    }

    public void display(int depth) {
        System.out.println(StringUtils.toStr('-', depth) + getName());
        for (Company child : children) {
            child.display(depth + 2);
        }
    }

    public void lineOfDuty() {
        for (Company child : children) {
            child.lineOfDuty();
        }
    }
}

package composite;

/**
 * Created by hero on 17-2-19.
 */
public class FinanceDepartment extends Company {
    public FinanceDepartment(String name) {
        super(name);
    }

    public void add(Company c) {

    }

    public void remove(Company c) {

    }

    public void display(int depth) {
        System.out.println(StringUtils.toStr('-', depth) + getName());
    }

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

package composite;

/**
 * 人力资源部,相当于树叶
 */
public class HRDepartment extends Company {
    public HRDepartment(String name) {
        super(name);
    }

    public void add(Company c) {

    }

    public void remove(Company c) {

    }

    public void display(int depth) {
        System.out.println(StringUtils.toStr('-', depth) + getName());
    }

    public void lineOfDuty() {
        System.out.println(getName() + " 员工招聘培训管理");
    }
}

package composite;

import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * Created by hero on 17-2-19.
 */
public class StringUtils {
    private static StringBuilder sb = new StringBuilder();
    private static ReentrantReadWriteLock lock = new ReentrantReadWriteLock(true);

    /**
     * @param c
     * @param num 字符c的个数
     * @return 返回num个c的String
     */
    public static String toStr(char c, int num) {
        try {
            lock.writeLock().lock();
            sb.delete(0, sb.length());
            for (int i = 0; i < num; i++) {
                sb.append(c);
            }
            return sb.toString();
        } finally {
            lock.writeLock().unlock();
        }
    }

    public static void main(String[] args) {
        String str = toStr('a', 5);
        System.out.println(str);
        str = toStr('b', -2);
        System.out.println(str);
    }
}

package composite;

/**
 * Created by hero on 17-2-19.
 */
public class Main {
    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 comp = new ConcreteCompany("上海华东分公司");
        comp.add(new HRDepartment("华东人力资源部"));
        comp.add(new FinanceDepartment("华东财务部"));
        root.add(comp);

        ConcreteCompany comp2 = new ConcreteCompany("南京办事处");
        comp2.add(new HRDepartment("南京人力资源部"));
        comp2.add(new FinanceDepartment("南京财务部"));
        comp.add(comp2);

        root.display(1);

        root.lineOfDuty();
    }
}