组合模式

// 抽象构件
public abstract class FileSystemComponent {
    protected String name;

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

    public abstract void display(int depth);
    public abstract long getSize();
}

// 叶子构件 - 文件
public class File extends FileSystemComponent {
    private long size;

    public File(String name, long size) {
        super(name);
        this.size = size;
    }

    @Override
    public void display(int depth) {
        String indent = "  ".repeat(depth);
        System.out.println(indent + "文件: " + name + " (" + size + " bytes)");
    }

    @Override
    public long getSize() {
        return size;
    }
}

// 容器构件 - 文件夹
public class Directory extends FileSystemComponent {
    private List<FileSystemComponent> children = new ArrayList<>();

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

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

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

    @Override
    public void display(int depth) {
        String indent = "  ".repeat(depth);
        System.out.println(indent + "文件夹: " + name);
        for (FileSystemComponent child : children) {
            child.display(depth + 1);
        }
    }

    @Override
    public long getSize() {
        long totalSize = 0;
        for (FileSystemComponent child : children) {
            totalSize += child.getSize();
        }
        return totalSize;
    }
}

// 客户端代码
public class Client {
    public static void main(String[] args) {
        // 创建文件系统结构
        Directory root = new Directory("根目录");

        Directory documents = new Directory("文档");
        documents.add(new File("报告.docx", 1024));
        documents.add(new File("计划.xlsx", 2048));

        Directory pictures = new Directory("图片");
        pictures.add(new File("照片1.jpg", 5120));
        pictures.add(new File("照片2.jpg", 6144));

        root.add(documents);
        root.add(pictures);
        root.add(new File("说明.txt", 512));

        // 显示文件系统结构
        System.out.println("文件系统结构:");
        root.display(0);

        System.out.println("\n总大小: " + root.getSize() + " bytes");
    }
}

// 抽象构件
public abstract class UIComponent {
    protected String name;

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

    public abstract void render();
    public abstract void add(UIComponent component);
    public abstract void remove(UIComponent component);
    public abstract UIComponent getChild(int index);
}

// 叶子构件 - 按钮
public class Button extends UIComponent {
    public Button(String name) {
        super(name);
    }

    @Override
    public void render() {
        System.out.println("渲染按钮: " + name);
    }

    @Override
    public void add(UIComponent component) {
        throw new UnsupportedOperationException("按钮不能添加子组件");
    }

    @Override
    public void remove(UIComponent component) {
        throw new UnsupportedOperationException("按钮不能移除子组件");
    }

    @Override
    public UIComponent getChild(int index) {
        throw new UnsupportedOperationException("按钮没有子组件");
    }
}

// 叶子构件 - 文本框
public class TextBox extends UIComponent {
    public TextBox(String name) {
        super(name);
    }

    @Override
    public void render() {
        System.out.println("渲染文本框: " + name);
    }

    @Override
    public void add(UIComponent component) {
        throw new UnsupportedOperationException("文本框不能添加子组件");
    }

    @Override
    public void remove(UIComponent component) {
        throw new UnsupportedOperationException("文本框不能移除子组件");
    }

    @Override
    public UIComponent getChild(int index) {
        throw new UnsupportedOperationException("文本框没有子组件");
    }
}

// 容器构件 - 面板
public class Panel extends UIComponent {
    private List<UIComponent> children = new ArrayList<>();

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

    @Override
    public void render() {
        System.out.println("渲染面板: " + name);
        for (UIComponent child : children) {
            child.render();
        }
    }

    @Override
    public void add(UIComponent component) {
        children.add(component);
    }

    @Override
    public void remove(UIComponent component) {
        children.remove(component);
    }

    @Override
    public UIComponent getChild(int index) {
        return children.get(index);
    }
}