简要说明

一、代码实现

• 定义抽象节点类 Node ，定义抽象方法 public abstract void print();
• 定义叶子节点类 LeafNode ，继承Node节点，实现 print()抽象方法，叶子节点没有子节点
• 定义子节点类BranchNode，继承Node节点，实现 print()抽象方法，子节点既可以有子节点，也又可以有叶子节点
• 定义一个树状目录结构，使用递归打印树状目录结构

import java.util.ArrayList;
import java.util.List;
/**
* @description: composite组合模式
* @author: flygo
* @time: 2022/7/20 14:05
*/
public class CompositeMain {
    
    public static void main(String[] args) {
        BranchNode root = new BranchNode("root");
        
        BranchNode chapter1 = new BranchNode("chapter1");
        BranchNode chapter2 = new BranchNode("chapter2");
        
        Node r1 = new LeafNode("r1");
        Node c11 = new LeafNode("c11");
        Node c12 = new LeafNode("c12");
        
        BranchNode b21 = new BranchNode("section21");
        Node c211 = new LeafNode("c211");
        Node c212 = new LeafNode("c212");
        
        root.add(chapter1).add(chapter2).add(r1);
        chapter1.add(c11).add(c12);
        chapter2.add(b21);
        b21.add(c211).add(c212);
        
        tree(root, 0);
    }
    
    private static void tree(Node node, int depth) {
        for (int i = 0; i < depth; i++) {
            System.out.print("--");
        }
        node.print();
        
        if (node instanceof BranchNode) {
            for (Node n : ((BranchNode) node).nodes) {
                tree(n, depth + 1);
            }
        }
    }
}
abstract class Node {
    public abstract void print();
}
/**
* @description: 叶子节点-不能有子节点
* @author: flygo
* @time: 2022/7/20 14:10
*/
class LeafNode extends Node {
    String content;
    
    public LeafNode(String content) {
        this.content = content;
    }
    
    @Override
    public void print() {
        System.out.println(content);
    }
}
/**
* @description: 子节点-可以有子节点和叶子节点
* @author: flygo
* @time: 2022/7/20 14:10
*/
class BranchNode extends Node {
    
    // 子节点可以有子节点和叶子节点
    List nodes = new ArrayList<>();
    
    String name;
    
    public BranchNode(String name) {
        this.name = name;
    }
    
    @Override
    public void print() {
        System.out.println(name);
    }
    
    public BranchNode add(Node node) {
        this.nodes.add(node);
        return this;
    }
}

二、源码地址

https://github.com/jxaufang168/Design-Patternshttps://github.com/jxaufang168/Design-Patterns