组合模式

package com.life.design.composite;

public abstract class MenuComponent {
    protected String name;
    protected int level;

    public void add(MenuComponent menuComponent) {
        throw new UnsupportedOperationException();
    }

    public void remove(MenuComponent menuComponent) {
        throw new UnsupportedOperationException();
    }

    public MenuComponent getChild(int index) {
        throw new UnsupportedOperationException();
    }

    public String getName() {
        return name;
    }

    public abstract void print();
}

package com.life.design.composite;

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

public class Menu extends MenuComponent {
    private List<MenuComponent> menuComponentList = new ArrayList<>();

    public Menu(String name,int level) {
        this.name = name;
        this.level = level;
    }

    @Override
    public void add(MenuComponent menuComponent) {
        menuComponentList.add(menuComponent);
    }

    @Override
    public void remove(MenuComponent menuComponent) {
        menuComponentList.remove(menuComponent);
    }

    @Override
    public MenuComponent getChild(int index) {
        return menuComponentList.get(index);
    }

    @Override
    public void print() {
        for (int i = 0; i < level; i++) {
            System.out.print("   ");
        }
        System.out.println(name);
        for (MenuComponent component : menuComponentList) {
            component.print();
        }
    }
}

package com.life.design.composite;

public class MenuItem extends MenuComponent {
    public MenuItem(String name, int level) {
        this.name = name;
        this.level = level;
    }

    @Override
    public void print() {
        for (int i = 0; i < level; i++) {
            System.out.print("   ");
        }
        System.out.println(name);
    }
}

package com.life.design.composite;

public class Client {
    public static void main(String[] args) {
        MenuComponent menu1 = new Menu("菜单管理",2);
        menu1.add(new MenuItem("页面访问",3));
        menu1.add(new MenuItem("展开菜单",3));
        menu1.add(new MenuItem("编辑菜单",3));
        menu1.add(new MenuItem("删除菜单",3));
        menu1.add(new MenuItem("新增菜单",3));

        MenuComponent menu2 = new Menu("权限管理",2);
        menu2.add(new MenuItem("页面访问",3));
        menu2.add(new MenuItem("提交保存",3));

        MenuComponent menu3 = new Menu("角色管理",2);
        menu3.add(new MenuItem("页面访问",3));
        menu3.add(new MenuItem("新增角色",3));
        menu3.add(new MenuItem("修改角色",3));

        MenuComponent component = new Menu("系统管理",1);
        component.add(menu1);
        component.add(menu2);
        component.add(menu3);

        component.print();

    }
}