概念：将对象组合成树形结构以表示“部分——整体”的层次结构。组合模式使得用户对单个对象和组合对象的使用具有一致性
核心：需求中是提现部分与整体层次的结构时，整体与部分可以一致对待。
操作树关系图

组合模式结构图

image.png

java代码：

  1. public class CompositeTest {
  2.     public static void main(String[] args) {
  3.         Component root = new Composite("根节点");
  4.         Component leaf1 = new Leaf("根节点叶子节点1");
  5.         Component leaf2 = new Leaf("根节点叶子节点2");
  6.         root.Add(leaf1);
  7.         root.Add(leaf2);
  9.         Component composite = new Composite("根节点组合节点1");
  10.         root.Add(composite);
  11.         Component leaf3 = new Leaf("根节点叶子节点3");
  12.         Component leaf4 = new Leaf("根节点叶子节点4");
  13.         composite.Add(leaf3);
  14.         composite.Add(leaf4);
  16.         root.Display(0);
  18.     }
  19. }
  21. //叶子节点和叶节点的抽象类
  22. public abstract class Component {
  23.     String name;
  25.     public Component(String name) {
  26.         this.name = name;
  27.     }
  29.     public String getName() {
  30.         return name;
  31.     }
  33.     public void setName(String name) {
  34.         this.name = name;
  35.     }
  37.     public abstract void Add(Component component);
  38.     public abstract void Remove(Component component);
  39.     public abstract void Display(int depth);
  40. }
  42. //叶节点
  43. public class Composite extends Component {
  44.     List<Component> list = new ArrayList<>();
  46.     public Composite(String name) {
  47.         super(name);
  48.     }
  50.     @Override
  51.     public void Add(Component component) {
  52.         list.add(component);
  53.     }
  55.     @Override
  56.     public void Remove(Component component) {
  57.         list.remove(component);
  58.     }
  60.     @Override
  61.     public void Display(int depth) {
  62.         for (int i = 0 ; i <= depth ; i ++){
  63.             System.out.print("-");
  64.         }
  65.         System.out.println(name);
  66.         for (Component component : list) {
  67.             component.Display(depth + 2);
  68.         }
  69.     }
  70. }
  72. //叶子节点
  73. public class Leaf extends Component {
  75.     public Leaf(String name) {
  76.         super(name);
  77.     }
  79.     @Override
  80.     public void Add(Component component) {
  81.         System.out.println("can not add by leaf");
  82.     }
  84.     @Override
  85.     public void Remove(Component component) {
  86.         System.out.println("can not remove by leaf");
  87.     }
  89.     @Override
  90.     public void Display(int depth) {
  91.         for (int i = 0 ; i <= depth ; i ++){
  92.             System.out.print("-");
  93.         }
  94.         System.out.println(name);
  95.     }
  96. }