设计模式｜组合模式

package com.elltor.designpattern.compose;

public abstract class Component {
    protected String componentName;


    public Component(String componentName) {
        this.componentName = componentName;
    }

    public abstract void add(Component component);

    public abstract void remove(Component component);

    public abstract void show(int depth);
}

package com.elltor.designpattern.compose;

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

public class Composite extends Component {
    private List<Component> childList = new ArrayList<>();

    public Composite(String componentName) {
        super(componentName);
    }

    @Override
    public void add(Component component) {
        childList.add(component);
    }

    @Override
    public void remove(Component component) {
        childList.remove(component);
    }

    @Override
    public void show(int depth) {
        for(int i=0;i<depth;i++){
            System.out.print('+');
        }

        System.out.println(componentName);

        for(int i=0;i<childList.size();i++){
            childList.get(i).show(depth+2);
        }
    }
}

package com.elltor.designpattern.compose;

public class Leaf extends Component {
    public Leaf(String componentName) {
        super(componentName);
    }

    @Override
    public void add(Component component) {
        System.out.println("叶子节点无法增加节点");
    }

    @Override
    public void remove(Component component) {
        System.out.println("叶子节点无法删除节点");
    }

    @Override
    public void show(int depth) {
        for (int i = 0; i < depth; i++) {
            System.out.print('+');
        }
        System.out.println(componentName);
    }
}

package com.elltor.designpattern.compose;

public class Main {
    public static void main(String[] args) {
        Composite root = new Composite("树根");
        root.add(new Leaf("叶子A"));
        root.add(new Leaf("叶子B"));

        Composite composite1 = new Composite("节点X");
        composite1.add(new Leaf("叶子XA"));
        composite1.add(new Leaf("叶子XB"));

        Composite composite2 = new Composite("节点Y");
        composite2.add(new Leaf("叶子YA"));
        composite2.add(new Leaf("叶子YB"));

        composite1.add(composite2);
        root.add(composite1);

        root.show(0);
    }
}

// 打印
+树根
+++叶子A
+++叶子B
+++节点X
+++++叶子XA
+++++叶子XB
+++++节点Y
+++++++叶子YA
+++++++叶子YB