组合模式

将对象组合成树型结构以表示“整体-部分”的层次结构，使得用户对单个对象和组合对象的使用具有一致性。

package com.strife.pattern.composite;

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

/**
 * @author mengzhenghao
 * @date 2022/5/30
 */
public class Code01{

    public static void main(String[] args) {
        Component component = new Composite("服装");

        Component manCoat = new Composite("男装");
        manCoat.addChild(new Leaf("上衣"));
        manCoat.addChild(new Leaf("下衣"));

        component.addChild(manCoat);

        Component womanCoat = new Composite("女装");
        womanCoat.addChild(new Leaf("裙子"));
        component.addChild(womanCoat);

        component.addChild(new Composite("鞋子"));

        component.printStruct("");
    }
}

/** 抽象构件角色类 */
abstract class Component {

    protected void addChild(Component child) {
        throw new UnsupportedOperationException();
    }

    protected void removeChild(Component child) {
        throw new UnsupportedOperationException();
    }

    /** 输出对象的自身结构 */
    protected abstract void printStruct(String preStr);
}

/** 树枝构件角色类 */
class Composite extends Component {
    private List<Component> childComponents = new ArrayList<>();
    private String name;

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

    @Override
    protected void printStruct(String preStr) {
        System.out.println(preStr + name);
        StringBuilder preStrBuilder = new StringBuilder(preStr);
        preStrBuilder.append("\t");
        for (Component component : childComponents) {
            component.printStruct(preStrBuilder.toString());
        }
        preStr = preStrBuilder.toString();
    }

    @Override
    protected void addChild(Component child) {
        childComponents.add(child);
    }

    @Override
    protected void removeChild(Component child) {
        childComponents.remove(child);
    }
}

/** 叶子构件角色类 */
class Leaf extends Component {
    private String name;

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

    @Override
    protected void printStruct(String preStr) {
        System.out.println(preStr + name);
    }
}