Java实现树形结构管理的组合设计模式

public abstract class AbstractFile {
    protected String name;
    public AbstractFile(String name) {
        this.name = name;
    }
    
    public abstract void display();
    
    public abstract void add(AbstractFile file);
    
    public abstract void remove(AbstractFile file);
}

public class File extends AbstractFile {
    public File(String name) {
        super(name);
    }
    
    @Override
    public void display() {
        System.out.println("这是文件:" + name);
    }
    
    @Override
    public void add(AbstractFile file) {
        throw new UnsupportedOperationException("文件不支持添加操作");
    }
    
    @Override
    public void remove(AbstractFile file) {
        throw new UnsupportedOperationException("文件不支持删除操作");
    }
}

public class Directory extends AbstractFile {
    private List<AbstractFile> fileList = new ArrayList<>();
    public Directory(String name) {
        super(name);
    }
    @Override
    public void add(AbstractFile file) {
        fileList.add(file);
    }
    @Override
    public void remove(AbstractFile file) {
        fileList.remove(file);
    }
    
    @Override
    public void display() {
        System.out.println("这是目录:" + name);
        fileList.forEach(AbstractFile::display);
    }
}

public class Demo {
    public static void main(String[] args) {
        AbstractFile root = new Directory("根目录");
        AbstractFile file1 = new File("文件1");
        AbstractFile file2 = new File("文件2");
        AbstractFile file3 = new File("文件3");
        AbstractFile file4 = new File("文件4");
        AbstractFile directory1 = new Directory("目录1");
        AbstractFile directory2 = new Directory("目录2");
        directory1.add(file1);
        directory1.add(file2);
        directory1.add(directory2);
        directory2.add(file3);
        directory2.add(file4);
        root.add(directory1);
        root.display();
    }
}