一起来学设计模式之代理模式

public interface Video {
    void play();
}

public class LocalVideo implements Video {
    private String filePath;
    public LocalVideo(String filePath) {
        this.filePath = filePath;
    }
    @Override
    public void play() {
        System.out.println("Playing local video: " + filePath);
    }
}
public class NetworkVideo implements Video {
    private String url;
    public NetworkVideo(String url) {
        this.url = url;
    }
    @Override
    public void play() {
        System.out.println("Playing network video: " + url);
    }
}

public class NetworkVideoProxy implements Video {
    private NetworkVideo networkVideo;
    public NetworkVideoProxy(NetworkVideo networkVideo) {
        this.networkVideo = networkVideo;
    }
    @Override
    public void play() {
        // 模拟权限校验
        boolean hasPermission = checkPermission();
        if (hasPermission) {
            networkVideo.play();
        } else {
            System.out.println("You do not have permission to play this video.");
        }
    }
    private boolean checkPermission() {
        // 模拟权限校验
        return true;
    }
}

public class Client {
    public static void main(String[] args) {
        // 播放本地视频
        Video localVideo = new LocalVideo("sample.mp4");
        localVideo.play();
        // 播放网络视频
        NetworkVideo networkVideo = new NetworkVideo("https://example.com/sample.mp4");
        Video networkVideoProxy = new NetworkVideoProxy(networkVideo);
        networkVideoProxy.play();
    }
}

public interface ProductService {
    ProductInfo getProductInfo(Long productId);
}

public class ProductServiceImpl implements ProductService {
    private final Map<Long, ProductInfo> productCache = new HashMap<>();
    private final ProductService productService;
    public ProductServiceImpl(ProductService productService) {
        this.productService = productService;
    }
    @Override
    public ProductInfo getProductInfo(Long productId) {
        ProductInfo productInfo = productCache.get(productId);
        if (productInfo != null) {
            System.out.println("Get product info from cache: " + productId);
            return productInfo;
        }
        productInfo = productService.getProductInfo(productId);
        productCache.put(productId, productInfo);
        return productInfo;
    }
}

public class Client {
    public static void main(String[] args) {
        ProductService productService = new ProductServiceImpl(new ProductAServiceImpl());
        ProductService proxy = new ProductServiceImpl(productService);
        ProductInfo productInfo = proxy.getProductInfo(123L);
        System.out.println("Product info: " + productInfo);
    }
}