【设计模式09】组合模式

前言

适用于树形结构，如公司的组织架构，目录和文件夹

UML类图

代码示例

package com.sw.learn.pattern.C_structre.c_composite;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

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

// 抽象组件
interface FileSystemComponent {
    void display(String indent);
}

// 叶子节点
class File implements FileSystemComponent {
    private String name;

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

    public void display(String indent) {
        System.out.println(indent + "- File: " + name);
    }
}

// 容器节点
class Directory implements FileSystemComponent {
    private String name;
    private List<FileSystemComponent> children = new ArrayList<>();

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

    public void add(FileSystemComponent component) {
        children.add(component);
    }

    public void display(String indent) {
        System.out.println(indent + "+ Directory: " + name);
        for (FileSystemComponent c : children) {
            c.display(indent + "  ");
        }
    }
}

// 使用示例
public class Main {
    public static void main(String[] args) {
        Directory root = new Directory("root");
        root.add(new File("file1.txt"));
        root.add(new File("file2.txt"));

        Directory subDir = new Directory("sub");
        subDir.add(new File("file3.txt"));

        root.add(subDir);

        root.display("");
    }
}