public abstract class Component {
  protected String name; //节点名
  public Component(String name){
    this.name = name;
  }

  public abstract void doSomething();
}

public class Composite extends Component {
  /**
   * 存储节点的容器
   */
  private List components = new ArrayList<>();

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

  @Override
  public void doSomething() {
    System.out.println(name);

    if(null!=components){
      for(Component c: components){
        c.doSomething();
      }
    }
  }

  public void addChild(Component child){
    components.add(child);
  }

  public void removeChild(Component child){
    components.remove(child);
  }

  public Component getChildren(int index){
    return components.get(index);
  }
}

public class Leaf extends Component {


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

  @Override
  public void doSomething() {
    System.out.println(name);
  }
}

public class Client {
  public static void main(String[] args){
    // 构造一个根节点
    Composite root = new Composite("Root");

    // 构造两个枝干节点
    Composite branch2 = new Composite("Branch2");
    Composite branch3 = new Composite("Branch3");

    // 构造两个叶子节点
    Leaf leaf1 = new Leaf("Leaf1");
    Leaf leaf2 = new Leaf("Leaf2");

    branch2.addChild(leaf1);
    branch3.addChild(leaf2);

    root.addChild(branch2);
    root.addChild(branch3);

    root.doSomething();
  }
}

输出结果:
Root
Branch2
Leaf1
Branch3
Leaf2