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第十章：外观模式 - 复杂系统的简化大师

news 2025/10/6 6:04:46

第十章：外观模式 - 复杂系统的简化大师

故事延续：统一接口的简洁之道

在Decorator展示完他的装饰艺术后，Facade面如冠玉、气质儒雅地走出，他步履从容，向众人微微颔首。这位气质儒雅的君子声音温和而清晰，给人一种安定和信任感。

"Decorator兄的动态装饰确实灵活，"Facade温和地说道，“但在复杂系统面前，客户端往往需要更简洁的接口。我的武学核心在于——为子系统中的一组接口提供一个一致的界面，定义一个高层接口，使得这一子系统更加容易使用。”

外观模式的武学精要

核心心法

Facade双手轻抚，空中浮现出一座宏伟建筑的门面，背后是错综复杂的结构：“我的十二字真言是——统一入口，简化调用。通过提供一个统一的高层接口，我隐藏了子系统的复杂性，使客户端只需要与这个门面交互，而不需要了解子系统内部的细节。”

C++ 代码实战
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <map>// 复杂子系统：家庭影院系统// 子系统1：投影仪
class Projector {
private:bool isOn_;std::string currentSource_;int brightness_;public:Projector() : isOn_(false), brightness_(50) {}void turnOn() {isOn_ = true;std::cout << "📽️ 投影仪已开启" << std::endl;}void turnOff() {isOn_ = false;std::cout << "📽️ 投影仪已关闭" << std::endl;}void setSource(const std::string& source) {currentSource_ = source;std::cout << "📽️ 投影仪输入源设置为: " << source << std::endl;}void setBrightness(int level) {brightness_ = level;std::cout << "📽️ 投影仪亮度设置为: " << level << "%" << std::endl;}void adjustFocus() {std::cout << "📽️ 调整投影仪焦距" << std::endl;}bool isOn() const {return isOn_;}
};// 子系统2：音响系统
class SoundSystem {
private:bool isOn_;int volume_;std::string soundMode_;bool isSurroundEnabled_;public:SoundSystem() : isOn_(false), volume_(30), soundMode_("标准"), isSurroundEnabled_(false) {}void turnOn() {isOn_ = true;std::cout << "🔊 音响系统已开启" << std::endl;}void turnOff() {isOn_ = false;std::cout << "🔊 音响系统已关闭" << std::endl;}void setVolume(int level) {volume_ = level;std::cout << "🔊 音量设置为: " << level << "%" << std::endl;}void setSoundMode(const std::string& mode) {soundMode_ = mode;std::cout << "🔊 音效模式设置为: " << mode << std::endl;}void enableSurroundSound() {isSurroundEnabled_ = true;std::cout << "🔊 环绕声已启用" << std::endl;}void disableSurroundSound() {isSurroundEnabled_ = false;std::cout << "🔊 环绕声已禁用" << std::endl;}bool isOn() const {return isOn_;}
};// 子系统3：蓝光播放器
class BluRayPlayer {
private:bool isOn_;bool isPlaying_;std::string currentMovie_;public:BluRayPlayer() : isOn_(false), isPlaying_(false) {}void turnOn() {isOn_ = true;std::cout << "📀 蓝光播放器已开启" << std::endl;}void turnOff() {isOn_ = false;isPlaying_ = false;std::cout << "📀 蓝光播放器已关闭" << std::endl;}void playMovie(const std::string& movie) {if (!isOn_) {std::cout << "❌ 请先开启蓝光播放器" << std::endl;return;}currentMovie_ = movie;isPlaying_ = true;std::cout << "🎬 开始播放电影: " << movie << std::endl;}void stopMovie() {isPlaying_ = false;std::cout << "⏹️ 停止播放电影: " << currentMovie_ << std::endl;currentMovie_.clear();}void pause() {if (isPlaying_) {std::cout << "⏸️ 电影已暂停: " << currentMovie_ << std::endl;}}bool isPlaying() const {return isPlaying_;}
};// 子系统4：灯光控制系统
class LightingSystem {
private:bool mainLightsOn_;bool ambientLightsOn_;int mainLightLevel_;int ambientLightLevel_;public:LightingSystem() : mainLightsOn_(true), ambientLightsOn_(false), mainLightLevel_(100), ambientLightLevel_(0) {}void turnOnMainLights() {mainLightsOn_ = true;std::cout << "💡 主灯已开启" << std::endl;}void turnOffMainLights() {mainLightsOn_ = false;std::cout << "💡 主灯已关闭" << std::endl;}void turnOnAmbientLights() {ambientLightsOn_ = true;std::cout << "✨ 氛围灯已开启" << std::endl;}void turnOffAmbientLights() {ambientLightsOn_ = false;std::cout << "✨ 氛围灯已关闭" << std::endl;}void setMainLightLevel(int level) {mainLightLevel_ = level;std::cout << "💡 主灯亮度设置为: " << level << "%" << std::endl;}void setAmbientLightLevel(int level) {ambientLightLevel_ = level;std::cout << "✨ 氛围灯亮度设置为: " << level << "%" << std::endl;}void setCinemaLighting() {turnOffMainLights();turnOnAmbientLights();setAmbientLightLevel(10);std::cout << "🎭 影院灯光模式已设置" << std::endl;}void setNormalLighting() {turnOnMainLights();turnOffAmbientLights();setMainLightLevel(100);std::cout << "🏠 正常灯光模式已设置" << std::endl;}
};// 子系统5：空调系统
class AirConditioning {
private:bool isOn_;int temperature_;std::string mode_;int fanSpeed_;public:AirConditioning() : isOn_(false), temperature_(22), mode_("自动"), fanSpeed_(2) {}void turnOn() {isOn_ = true;std::cout << "❄️ 空调已开启" << std::endl;}void turnOff() {isOn_ = false;std::cout << "❄️ 空调已关闭" << std::endl;}void setTemperature(int temp) {temperature_ = temp;std::cout << "❄️ 温度设置为: " << temp << "°C" << std::endl;}void setMode(const std::string& mode) {mode_ = mode;std::cout << "❄️ 空调模式设置为: " << mode << std::endl;}void setFanSpeed(int speed) {fanSpeed_ = speed;std::cout << "❄️ 风扇速度设置为: " << speed << "档" << std::endl;}void setComfortMode() {setTemperature(22);setMode("自动");setFanSpeed(2);std::cout << "😊 舒适模式已设置" << std::endl;}
};// 外观类：家庭影院外观
class HomeTheaterFacade {
private:std::shared_ptr<Projector> projector_;std::shared_ptr<SoundSystem> soundSystem_;std::shared_ptr<BluRayPlayer> bluRayPlayer_;std::shared_ptr<LightingSystem> lightingSystem_;std::shared_ptr<AirConditioning> airConditioning_;public:HomeTheaterFacade(std::shared_ptr<Projector> projector,std::shared_ptr<SoundSystem> soundSystem,std::shared_ptr<BluRayPlayer> bluRayPlayer,std::shared_ptr<LightingSystem> lightingSystem,std::shared_ptr<AirConditioning> airConditioning): projector_(projector), soundSystem_(soundSystem), bluRayPlayer_(bluRayPlayer),lightingSystem_(lightingSystem), airConditioning_(airConditioning) {}// 高级接口：看电影模式void watchMovie(const std::string& movie) {std::cout << "\n🎭 准备观看电影: " << movie << std::endl;std::cout << "========================" << std::endl;// 1. 开启所有设备std::cout << "\n1. 开启设备..." << std::endl;projector_->turnOn();soundSystem_->turnOn();bluRayPlayer_->turnOn();airConditioning_->turnOn();// 2. 配置设备std::cout << "\n2. 配置设备..." << std::endl;projector_->setSource("HDMI");projector_->setBrightness(80);projector_->adjustFocus();soundSystem_->setVolume(60);soundSystem_->setSoundMode("影院");soundSystem_->enableSurroundSound();airConditioning_->setComfortMode();// 3. 设置灯光std::cout << "\n3. 设置环境..." << std::endl;lightingSystem_->setCinemaLighting();// 4. 开始播放std::cout << "\n4. 开始播放..." << std::endl;bluRayPlayer_->playMovie(movie);std::cout << "\n✅ 电影模式准备完成！享受观影时光！" << std::endl;}// 高级接口：结束电影void endMovie() {std::cout << "\n🛑 结束观影..." << std::endl;std::cout << "==================" << std::endl;bluRayPlayer_->stopMovie();// 恢复正常灯光lightingSystem_->setNormalLighting();std::cout << "\n✅ 观影结束！" << std::endl;}// 高级接口：只听音乐模式void listenToMusic() {std::cout << "\n🎵 音乐欣赏模式" << std::endl;std::cout << "================" << std::endl;soundSystem_->turnOn();soundSystem_->setVolume(50);soundSystem_->setSoundMode("音乐");soundSystem_->enableSurroundSound();lightingSystem_->setAmbientLightLevel(30);airConditioning_->setComfortMode();std::cout << "\n✅ 音乐模式准备完成！" << std::endl;}// 高级接口：游戏模式void playGame() {std::cout << "\n🎮 游戏模式" << std::endl;std::cout << "============" << std::endl;projector_->turnOn();projector_->setSource("游戏");projector_->setBrightness(100);soundSystem_->turnOn();soundSystem_->setVolume(70);soundSystem_->setSoundMode("游戏");lightingSystem_->setMainLightLevel(70);airConditioning_->setTemperature(20);airConditioning_->setMode("制冷");std::cout << "\n✅ 游戏模式准备完成！" << std::endl;}// 高级接口：关闭所有设备void turnOffAll() {std::cout << "\n🔌 关闭所有设备..." << std::endl;std::cout << "==================" << std::endl;if (bluRayPlayer_->isPlaying()) {bluRayPlayer_->stopMovie();}projector_->turnOff();soundSystem_->turnOff();bluRayPlayer_->turnOff();airConditioning_->turnOff();lightingSystem_->setNormalLighting();std::cout << "\n✅ 所有设备已关闭！" << std::endl;}// 高级接口：快速设置void quickSetup(const std::string& mode) {if (mode == "电影") {watchMovie("默认电影");} else if (mode == "音乐") {listenToMusic();} else if (mode == "游戏") {playGame();} else {std::cout << "❌ 未知模式: " << mode << std::endl;}}// 状态查询void getStatus() const {std::cout << "\n📊 家庭影院状态" << std::endl;std::cout << "================" << std::endl;std::cout << "投影仪: " << (projector_->isOn() ? "开启" : "关闭") << std::endl;std::cout << "音响系统: " << (soundSystem_->isOn() ? "开启" : "关闭") << std::endl;std::cout << "蓝光播放器: " << (bluRayPlayer_->isPlaying() ? "播放中" : "停止") << std::endl;}
};

UML 武功秘籍图

uses
uses
uses
uses
uses
Projector
-bool isOn_
-string currentSource_
-int brightness_
+turnOn() : void
+turnOff() : void
+setSource(string) : void
+setBrightness(int) : void
+adjustFocus() : void
+isOn() : bool
SoundSystem
-bool isOn_
-int volume_
-string soundMode_
-bool isSurroundEnabled_
+turnOn() : void
+turnOff() : void
+setVolume(int) : void
+setSoundMode(string) : void
+enableSurroundSound() : void
+disableSurroundSound() : void
+isOn() : bool
BluRayPlayer
-bool isOn_
-bool isPlaying_
-string currentMovie_
+turnOn() : void
+turnOff() : void
+playMovie(string) : void
+stopMovie() : void
+pause() : void
+isPlaying() : bool
LightingSystem
-bool mainLightsOn_
-bool ambientLightsOn_
-int mainLightLevel_
-int ambientLightLevel_
+turnOnMainLights() : void
+turnOffMainLights() : void
+turnOnAmbientLights() : void
+turnOffAmbientLights() : void
+setMainLightLevel(int) : void
+setAmbientLightLevel(int) : void
+setCinemaLighting() : void
+setNormalLighting() : void
AirConditioning
-bool isOn_
-int temperature_
-string mode_
-int fanSpeed_
+turnOn() : void
+turnOff() : void
+setTemperature(int) : void
+setMode(string) : void
+setFanSpeed(int) : void
+setComfortMode() : void
HomeTheaterFacade
-shared_ptr<Projector> projector_
-shared_ptr<SoundSystem> soundSystem_
-shared_ptr<BluRayPlayer> bluRayPlayer_
-shared_ptr<LightingSystem> lightingSystem_
-shared_ptr<AirConditioning> airConditioning_
+watchMovie(string) : void
+endMovie() : void
+listenToMusic() : void
+playGame() : void
+turnOffAll() : void
+quickSetup(string) : void
+getStatus() : void

实战演练：电商订单处理系统

#include <map>
#include <algorithm>// 更复杂的外观模式应用：电商订单处理系统// 子系统1：库存管理
class InventoryManager {
private:std::map<std::string, int> inventory_;public:InventoryManager() {// 初始化库存inventory_ = {{"iPhone14", 50},{"MacBookPro", 20},{"AirPods", 100},{"iPad", 30}};}bool checkStock(const std::string& productId, int quantity) {auto it = inventory_.find(productId);if (it != inventory_.end() && it->second >= quantity) {std::cout << "📦 库存检查: " << productId << " 有足够库存 (" << it->second << "个)" << std::endl;return true;}std::cout << "❌ 库存检查: " << productId << " 库存不足" << std::endl;return false;}void updateStock(const std::string& productId, int quantity) {auto it = inventory_.find(productId);if (it != inventory_.end()) {it->second -= quantity;std::cout << "📦 更新库存: " << productId << " 减少 " << quantity << "个，剩余 " << it->second << "个" << std::endl;}}void restoreStock(const std::string& productId, int quantity) {auto it = inventory_.find(productId);if (it != inventory_.end()) {it->second += quantity;std::cout << "📦 恢复库存: " << productId << " 增加 " << quantity << "个，现在 " << it->second << "个" << std::endl;}}void displayInventory() const {std::cout << "\n📊 当前库存:" << std::endl;for (const auto& item : inventory_) {std::cout << "  " << item.first << ": " << item.second << "个" << std::endl;}}
};// 子系统2：支付处理
class PaymentProcessor {
private:double balance_;public:PaymentProcessor() : balance_(10000.0) {}bool processPayment(const std::string& orderId, double amount, const std::string& paymentMethod) {std::cout << "💳 处理支付: 订单 " << orderId << " 金额 $" << amount << " 方式 " << paymentMethod << std::endl;// 模拟支付处理if (amount <= balance_) {balance_ -= amount;std::cout << "✅ 支付成功! 余额: $" << balance_ << std::endl;return true;} else {std::cout << "❌ 支付失败: 余额不足" << std::endl;return false;}}void refundPayment(const std::string& orderId, double amount) {balance_ += amount;std::cout << "💳 退款处理: 订单 " << orderId << " 金额 $" << amount << " 已退回" << std::endl;std::cout << "💰 当前余额: $" << balance_ << std::endl;}double getBalance() const {return balance_;}
};// 子系统3：物流配送
class ShippingService {
private:int nextTrackingId_;public:ShippingService() : nextTrackingId_(1000) {}std::string scheduleDelivery(const std::string& orderId, const std::string& address, const std::vector<std::string>& items) {std::string trackingId = "TRK" + std::to_string(nextTrackingId_++);std::cout << "🚚 安排配送: 订单 " << orderId << std::endl;std::cout << "   地址: " << address << std::endl;std::cout << "   跟踪号: " << trackingId << std::endl;std::cout << "   物品: ";for (const auto& item : items) {std::cout << item << " ";}std::cout << std::endl;return trackingId;}void cancelDelivery(const std::string& trackingId) {std::cout << "🚚 取消配送: 跟踪号 " << trackingId << std::endl;}void updateDeliveryStatus(const std::string& trackingId, const std::string& status) {std::cout << "🚚 更新配送状态: " << trackingId << " -> " << status << std::endl;}
};// 子系统4：邮件通知
class EmailService {
public:void sendOrderConfirmation(const std::string& email, const std::string& orderId, double amount) {std::cout << "📧 发送订单确认邮件到: " << email << std::endl;std::cout << "   订单号: " << orderId << std::endl;std::cout << "   金额: $" << amount << std::endl;std::cout << "   内容: 感谢您的订购！我们会尽快处理您的订单。" << std::endl;}void sendShippingNotification(const std::string& email, const std::string& orderId, const std::string& trackingId) {std::cout << "📧 发送发货通知邮件到: " << email << std::endl;std::cout << "   订单号: " << orderId << std::endl;std::cout << "   跟踪号: " << trackingId << std::endl;std::cout << "   内容: 您的订单已发货！您可以使用跟踪号查询物流状态。" << std::endl;}void sendCancellationNotification(const std::string& email, const std::string& orderId) {std::cout << "📧 发送取消通知邮件到: " << email << std::endl;std::cout << "   订单号: " << orderId << std::endl;std::cout << "   内容: 您的订单已被取消。如有疑问请联系客服。" << std::endl;}
};// 子系统5：订单数据库
class OrderDatabase {
private:std::map<std::string, std::map<std::string, std::string>> orders_;int nextOrderId_;public:OrderDatabase() : nextOrderId_(1000) {}std::string createOrder(const std::string& customerEmail, const std::map<std::string, int>& items, double totalAmount) {std::string orderId = "ORD" + std::to_string(nextOrderId_++);std::map<std::string, std::string> orderInfo;orderInfo["customerEmail"] = customerEmail;orderInfo["status"] = "created";orderInfo["totalAmount"] = std::to_string(totalAmount);// 保存商品信息std::string itemsStr;for (const auto& item : items) {itemsStr += item.first + ":" + std::to_string(item.second) + ";";}orderInfo["items"] = itemsStr;orders_[orderId] = orderInfo;std::cout << "💾 创建订单: " << orderId << " 客户: " << customerEmail << " 金额: $" << totalAmount << std::endl;return orderId;}void updateOrderStatus(const std::string& orderId, const std::string& status) {auto it = orders_.find(orderId);if (it != orders_.end()) {it->second["status"] = status;std::cout << "💾 更新订单状态: " << orderId << " -> " << status << std::endl;}}std::map<std::string, std::string> getOrder(const std::string& orderId) const {auto it = orders_.find(orderId);if (it != orders_.end()) {return it->second;}return {};}void displayAllOrders() const {std::cout << "\n📋 所有订单:" << std::endl;for (const auto& order : orders_) {std::cout << "  订单号: " << order.first << " | 状态: " << order.second.at("status") << " | 金额: $" << order.second.at("totalAmount") << std::endl;}}
};// 外观类：订单处理外观
class OrderProcessingFacade {
private:std::shared_ptr<InventoryManager> inventoryManager_;std::shared_ptr<PaymentProcessor> paymentProcessor_;std::shared_ptr<ShippingService> shippingService_;std::shared_ptr<EmailService> emailService_;std::shared_ptr<OrderDatabase> orderDatabase_;public:OrderProcessingFacade(std::shared_ptr<InventoryManager> inventoryManager,std::shared_ptr<PaymentProcessor> paymentProcessor,std::shared_ptr<ShippingService> shippingService,std::shared_ptr<EmailService> emailService,std::shared_ptr<OrderDatabase> orderDatabase): inventoryManager_(inventoryManager), paymentProcessor_(paymentProcessor),shippingService_(shippingService), emailService_(emailService), orderDatabase_(orderDatabase) {}// 高级接口：处理新订单std::string processNewOrder(const std::string& customerEmail, const std::string& address, const std::map<std::string, int>& items, const std::string& paymentMethod) {std::cout << "\n🛒 处理新订单" << std::endl;std::cout << "==============" << std::endl;// 1. 检查库存std::cout << "\n1. 检查库存..." << std::endl;for (const auto& item : items) {if (!inventoryManager_->checkStock(item.first, item.second)) {throw std::runtime_error("库存不足: " + item.first);}}// 2. 计算总金额double totalAmount = calculateTotalAmount(items);std::cout << "💰 订单总金额: $" << totalAmount << std::endl;// 3. 创建订单记录std::string orderId = orderDatabase_->createOrder(customerEmail, items, totalAmount);// 4. 处理支付std::cout << "\n2. 处理支付..." << std::endl;if (!paymentProcessor_->processPayment(orderId, totalAmount, paymentMethod)) {orderDatabase_->updateOrderStatus(orderId, "payment_failed");throw std::runtime_error("支付失败");}// 5. 更新库存std::cout << "\n3. 更新库存..." << std::endl;for (const auto& item : items) {inventoryManager_->updateStock(item.first, item.second);}// 6. 安排配送std::cout << "\n4. 安排配送..." << std::endl;std::vector<std::string> itemNames;for (const auto& item : items) {itemNames.push_back(item.first + " x" + std::to_string(item.second));}std::string trackingId = shippingService_->scheduleDelivery(orderId, address, itemNames);// 7. 发送确认邮件std::cout << "\n5. 发送通知..." << std::endl;emailService_->sendOrderConfirmation(customerEmail, orderId, totalAmount);// 8. 更新订单状态orderDatabase_->updateOrderStatus(orderId, "processing");std::cout << "\n✅ 订单处理完成! 订单号: " << orderId << " 跟踪号: " << trackingId << std::endl;return orderId;}// 高级接口：取消订单void cancelOrder(const std::string& orderId) {std::cout << "\n❌ 取消订单: " << orderId << std::endl;std::cout << "================" << std::endl;auto orderInfo = orderDatabase_->getOrder(orderId);if (orderInfo.empty()) {std::cout << "❌ 订单不存在: " << orderId << std::endl;return;}// 1. 退款double amount = std::stod(orderInfo["totalAmount"]);paymentProcessor_->refundPayment(orderId, amount);// 2. 恢复库存std::map<std::string, int> items = parseItems(orderInfo["items"]);for (const auto& item : items) {inventoryManager_->restoreStock(item.first, item.second);}// 3. 取消配送// 注意：实际系统中需要根据跟踪号取消shippingService_->cancelDelivery("TRK" + orderId.substr(3));// 4. 发送取消通知emailService_->sendCancellationNotification(orderInfo["customerEmail"], orderId);// 5. 更新订单状态orderDatabase_->updateOrderStatus(orderId, "cancelled");std::cout << "\n✅ 订单取消完成!" << std::endl;}// 高级接口：发货处理void shipOrder(const std::string& orderId) {std::cout << "\n🚚 处理订单发货: " << orderId << std::endl;std::cout << "==================" << std::endl;auto orderInfo = orderDatabase_->getOrder(orderId);if (orderInfo.empty()) {std::cout << "❌ 订单不存在: " << orderId << std::endl;return;}// 更新配送状态shippingService_->updateDeliveryStatus("TRK" + orderId.substr(3), "shipped");// 发送发货通知emailService_->sendShippingNotification(orderInfo["customerEmail"], orderId, "TRK" + orderId.substr(3));// 更新订单状态orderDatabase_->updateOrderStatus(orderId, "shipped");std::cout << "\n✅ 订单发货完成!" << std::endl;}// 高级接口：获取系统状态void getSystemStatus() const {std::cout << "\n📈 系统状态概览" << std::endl;std::cout << "================" << std::endl;inventoryManager_->displayInventory();std::cout << "\n💰 账户余额: $" << paymentProcessor_->getBalance() << std::endl;orderDatabase_->displayAllOrders();}private:double calculateTotalAmount(const std::map<std::string, int>& items) const {// 模拟价格计算std::map<std::string, double> prices = {{"iPhone14", 999.0},{"MacBookPro", 1999.0},{"AirPods", 199.0},{"iPad", 599.0}};double total = 0.0;for (const auto& item : items) {auto it = prices.find(item.first);if (it != prices.end()) {total += it->second * item.second;}}return total;}std::map<std::string, int> parseItems(const std::string& itemsStr) const {std::map<std::string, int> items;size_t start = 0;size_t end = itemsStr.find(';');while (end != std::string::npos) {std::string item = itemsStr.substr(start, end - start);size_t colonPos = item.find(':');if (colonPos != std::string::npos) {std::string productId = item.substr(0, colonPos);int quantity = std::stoi(item.substr(colonPos + 1));items[productId] = quantity;}start = end + 1;end = itemsStr.find(';', start);}return items;}
};

外观模式的招式解析

招式一：分层外观模式
// 分层外观：为不同层级的用户提供不同复杂度的接口
class LayeredFacadeSystem {
private:std::shared_ptr<HomeTheaterFacade> basicFacade_;std::shared_ptr<OrderProcessingFacade> orderFacade_;public:LayeredFacadeSystem() {// 初始化家庭影院子系统auto projector = std::make_shared<Projector>();auto soundSystem = std::make_shared<SoundSystem>();auto bluRayPlayer = std::make_shared<BluRayPlayer>();auto lightingSystem = std::make_shared<LightingSystem>();auto airConditioning = std::make_shared<AirConditioning>();basicFacade_ = std::make_shared<HomeTheaterFacade>(projector, soundSystem, bluRayPlayer, lightingSystem, airConditioning);// 初始化订单处理子系统auto inventoryManager = std::make_shared<InventoryManager>();auto paymentProcessor = std::make_shared<PaymentProcessor>();auto shippingService = std::make_shared<ShippingService>();auto emailService = std::make_shared<EmailService>();auto orderDatabase = std::make_shared<OrderDatabase>();orderFacade_ = std::make_shared<OrderProcessingFacade>(inventoryManager, paymentProcessor, shippingService, emailService, orderDatabase);}// 初级用户接口：极简操作class SimpleInterface {private:std::shared_ptr<LayeredFacadeSystem> parent_;public:SimpleInterface(std::shared_ptr<LayeredFacadeSystem> parent) : parent_(parent) {}void watchMovie() {parent_->basicFacade_->watchMovie("最新电影");}void stopMovie() {parent_->basicFacade_->endMovie();}void orderProduct(const std::string& product, int quantity) {std::map<std::string, int> items = {{product, quantity}};try {parent_->orderFacade_->processNewOrder("customer@example.com", "默认地址", items, "信用卡");} catch (const std::exception& e) {std::cout << "❌ 订购失败: " << e.what() << std::endl;}}};// 高级用户接口：更多控制选项class AdvancedInterface {private:std::shared_ptr<LayeredFacadeSystem> parent_;public:AdvancedInterface(std::shared_ptr<LayeredFacadeSystem> parent) : parent_(parent) {}void customizeMovieExperience(const std::string& movie, int volume, int brightness) {// 先使用基础功能parent_->basicFacade_->watchMovie(movie);// 然后进行自定义调整// 这里可以访问子系统进行更精细的控制}void bulkOrder(const std::map<std::string, int>& items) {try {parent_->orderFacade_->processNewOrder("vip@example.com", "VIP地址", items, "企业账户");} catch (const std::exception& e) {std::cout << "❌ 批量订购失败: " << e.what() << std::endl;}}void getDetailedStatus() {parent_->orderFacade_->getSystemStatus();}};// 管理员接口：完整系统控制class AdminInterface {private:std::shared_ptr<LayeredFacadeSystem> parent_;public:AdminInterface(std::shared_ptr<LayeredFacadeSystem> parent) : parent_(parent) {}void systemMaintenance() {std::cout << "\n🔧 系统维护模式" << std::endl;std::cout << "===============" << std::endl;// 可以访问所有子系统进行维护操作parent_->orderFacade_->getSystemStatus();// 执行维护任务...std::cout << "🛠️ 执行数据库优化..." << std::endl;std::cout << "🛠️ 清理临时文件..." << std::endl;std::cout << "🛠️ 更新系统配置..." << std::endl;std::cout << "✅ 系统维护完成!" << std::endl;}void emergencyShutdown() {std::cout << "\n🛑 紧急关闭系统" << std::endl;parent_->basicFacade_->turnOffAll();std::cout << "所有子系统已安全关闭!" << std::endl;}};// 获取不同层级的接口SimpleInterface getSimpleInterface() {return SimpleInterface(shared_from_this());}AdvancedInterface getAdvancedInterface() {return AdvancedInterface(shared_from_this());}AdminInterface getAdminInterface() {return AdminInterface(shared_from_this());}
};
招式二：智能外观模式
// 智能外观：根据上下文自动选择最佳配置
class SmartFacade {
private:std::shared_ptr<HomeTheaterFacade> homeTheater_;std::shared_ptr<OrderProcessingFacade> orderProcessor_;public:SmartFacade(std::shared_ptr<HomeTheaterFacade> homeTheater,std::shared_ptr<OrderProcessingFacade> orderProcessor): homeTheater_(homeTheater), orderProcessor_(orderProcessor) {}// 情景感知模式选择void smartMovieMode(const std::string& movieType) {std::cout << "\n🤖 智能电影模式: " << movieType << std::endl;std::cout << "====================" << std::endl;if (movieType == "动作片") {homeTheater_->quickSetup("电影");// 动作片需要更高的音量和对比度std::cout << "💥 动作片优化: 增强低音，提高对比度" << std::endl;} else if (movieType == "文艺片") {homeTheater_->quickSetup("电影");// 文艺片需要柔和的灯光和音效std::cout << "🎨 文艺片优化: 柔和灯光，清晰对白" << std::endl;} else if (movieType == "恐怖片") {homeTheater_->quickSetup("电影");// 恐怖片需要特殊的音效和环境std::cout << "👻 恐怖片优化: 环绕声效，调暗灯光" << std::endl;} else {homeTheater_->quickSetup("电影");}}// 智能订单推荐void smartOrderRecommendation(const std::string& customerType) {std::cout << "\n🤖 智能订单推荐: " << customerType << std::endl;std::cout << "====================" << std::endl;std::map<std::string, int> recommendedItems;if (customerType == "学生") {recommendedItems = {{"iPad", 1}, {"AirPods", 1}};std::cout << "🎓 学生推荐: iPad + AirPods 组合" << std::endl;} else if (customerType == "商务人士") {recommendedItems = {{"MacBookPro", 1}, {"iPhone14", 1}};std::cout << "💼 商务推荐: MacBook Pro + iPhone 组合" << std::endl;} else if (customerType == "科技爱好者") {recommendedItems = {{"iPhone14", 1}, {"iPad", 1}, {"AirPods", 1}};std::cout << "🚀 科技爱好者推荐: 苹果全家桶" << std::endl;} else {recommendedItems = {{"iPhone14", 1}};std::cout << "😊 默认推荐: iPhone 14" << std::endl;}try {orderProcessor_->processNewOrder(customerType + "@example.com", "智能推荐地址", recommendedItems, "智能支付");} catch (const std::exception& e) {std::cout << "❌ 智能推荐失败: " << e.what() << std::endl;}}// 自适应系统优化void adaptiveOptimization() {std::cout << "\n🔧 自适应系统优化" << std::endl;std::cout << "==================" << std::endl;// 检查系统状态并优化orderProcessor_->getSystemStatus();// 基于当前状态进行优化std::cout << "⚡ 优化系统性能..." << std::endl;std::cout << "📊 分析使用模式..." << std::endl;std::cout << "🎯 应用最佳实践..." << std::endl;std::cout << "✅ 自适应优化完成!" << std::endl;}
};

完整测试代码

// 测试外观模式
void testFacadePattern() {std::cout << "=== 外观模式测试开始 ===" << std::endl;// 测试家庭影院外观std::cout << "\n--- 家庭影院外观测试 ---" << std::endl;// 创建子系统auto projector = std::make_shared<Projector>();auto soundSystem = std::make_shared<SoundSystem>();auto bluRayPlayer = std::make_shared<BluRayPlayer>();auto lightingSystem = std::make_shared<LightingSystem>();auto airConditioning = std::make_shared<AirConditioning>();// 创建外观auto homeTheater = std::make_shared<HomeTheaterFacade>(projector, soundSystem, bluRayPlayer, lightingSystem, airConditioning);// 使用外观的简单接口std::cout << "\n🎬 测试电影模式..." << std::endl;homeTheater->watchMovie("阿凡达：水之道");std::cout << "\n📊 检查系统状态..." << std::endl;homeTheater->getStatus();std::cout << "\n🎵 测试音乐模式..." << std::endl;homeTheater->listenToMusic();std::cout << "\n🛑 结束测试..." << std::endl;homeTheater->turnOffAll();// 测试电商订单处理外观std::cout << "\n--- 电商订单处理外观测试 ---" << std::endl;auto inventoryManager = std::make_shared<InventoryManager>();auto paymentProcessor = std::make_shared<PaymentProcessor>();auto shippingService = std::make_shared<ShippingService>();auto emailService = std::make_shared<EmailService>();auto orderDatabase = std::make_shared<OrderDatabase>();auto orderProcessor = std::make_shared<OrderProcessingFacade>(inventoryManager, paymentProcessor, shippingService, emailService, orderDatabase);// 处理测试订单std::cout << "\n🛒 处理测试订单..." << std::endl;std::map<std::string, int> orderItems = {{"iPhone14", 1}, {"AirPods", 2}};try {std::string orderId = orderProcessor->processNewOrder("test@example.com", "测试地址 123号", orderItems, "信用卡");std::cout << "\n📦 模拟订单发货..." << std::endl;orderProcessor->shipOrder(orderId);std::cout << "\n📊 检查系统状态..." << std::endl;orderProcessor->getSystemStatus();} catch (const std::exception& e) {std::cout << "❌ 订单处理错误: " << e.what() << std::endl;}// 测试分层外观std::cout << "\n--- 分层外观测试 ---" << std::endl;auto layeredSystem = std::make_shared<LayeredFacadeSystem>();// 初级用户接口auto simpleUI = layeredSystem->getSimpleInterface();std::cout << "\n👶 初级用户操作..." << std::endl;simpleUI.watchMovie();simpleUI.orderProduct("iPad", 1);// 高级用户接口auto advancedUI = layeredSystem->getAdvancedInterface();std::cout << "\n👨‍💼 高级用户操作..." << std::endl;std::map<std::string, int> bulkItems = {{"MacBookPro", 2}, {"iPhone14", 3}};advancedUI.bulkOrder(bulkItems);advancedUI.getDetailedStatus();// 测试智能外观std::cout << "\n--- 智能外观测试 ---" << std::endl;auto smartFacade = std::make_shared<SmartFacade>(homeTheater, orderProcessor);std::cout << "\n🎭 智能电影模式测试..." << std::endl;smartFacade->smartMovieMode("动作片");std::cout << "\n🛒 智能订单推荐测试..." << std::endl;smartFacade->smartOrderRecommendation("学生");std::cout << "\n🔧 自适应优化测试..." << std::endl;smartFacade->adaptiveOptimization();std::cout << "\n=== 外观模式测试结束 ===" << std::endl;
}// 实战应用：智能家居控制系统
class SmartHomeControlSystem {
private:std::shared_ptr<HomeTheaterFacade> homeTheater_;std::shared_ptr<LayeredFacadeSystem> layeredSystem_;std::shared_ptr<SmartFacade> smartFacade_;public:SmartHomeControlSystem() {initializeSystems();}void initializeSystems() {// 初始化家庭影院子系统auto projector = std::make_shared<Projector>();auto soundSystem = std::make_shared<SoundSystem>();auto bluRayPlayer = std::make_shared<BluRayPlayer>();auto lightingSystem = std::make_shared<LightingSystem>();auto airConditioning = std::make_shared<AirConditioning>();homeTheater_ = std::make_shared<HomeTheaterFacade>(projector, soundSystem, bluRayPlayer, lightingSystem, airConditioning);// 初始化分层系统layeredSystem_ = std::make_shared<LayeredFacadeSystem>();// 初始化订单处理子系统（模拟）auto inventoryManager = std::make_shared<InventoryManager>();auto paymentProcessor = std::make_shared<PaymentProcessor>();auto shippingService = std::make_shared<ShippingService>();auto emailService = std::make_shared<EmailService>();auto orderDatabase = std::make_shared<OrderDatabase>();auto orderProcessor = std::make_shared<OrderProcessingFacade>(inventoryManager, paymentProcessor, shippingService, emailService, orderDatabase);// 初始化智能外观smartFacade_ = std::make_shared<SmartFacade>(homeTheater_, orderProcessor);}void run() {std::cout << "\n🏠 智能家居控制系统启动" << std::endl;std::cout << "========================" << std::endl;while (true) {std::cout << "\n请选择操作模式:" << std::endl;std::cout << "1. 家庭娱乐" << std::endl;std::cout << "2. 智能购物" << std::endl;std::cout << "3. 系统状态" << std::endl;std::cout << "4. 退出" << std::endl;std::cout << "选择: ";int choice;std::cin >> choice;switch (choice) {case 1:entertainmentMode();break;case 2:shoppingMode();break;case 3:systemStatus();break;case 4:std::cout << "👋 再见!" << std::endl;return;default:std::cout << "❌ 无效选择" << std::endl;}}}private:void entertainmentMode() {std::cout << "\n🎮 家庭娱乐模式" << std::endl;std::cout << "===============" << std::endl;std::cout << "请选择娱乐项目:" << std::endl;std::cout << "1. 智能电影" << std::endl;std::cout << "2. 音乐欣赏" << std::endl;std::cout << "3. 游戏模式" << std::endl;std::cout << "选择: ";int choice;std::cin >> choice;switch (choice) {case 1:{std::cout << "请输入电影类型 (动作片/文艺片/恐怖片): ";std::string movieType;std::cin >> movieType;smartFacade_->smartMovieMode(movieType);}break;case 2:homeTheater_->listenToMusic();break;case 3:homeTheater_->playGame();break;default:std::cout << "❌ 无效选择" << std::endl;}}void shoppingMode() {std::cout << "\n🛒 智能购物模式" << std::endl;std::cout << "===============" << std::endl;std::cout << "请选择购物方式:" << std::endl;std::cout << "1. 智能推荐" << std::endl;std::cout << "2. 快速订购" << std::endl;std::cout << "选择: ";int choice;std::cin >> choice;switch (choice) {case 1:{std::cout << "请输入用户类型 (学生/商务人士/科技爱好者): ";std::string userType;std::cin >> userType;smartFacade_->smartOrderRecommendation(userType);}break;case 2:{auto simpleUI = layeredSystem_->getSimpleInterface();std::cout << "请输入产品名称: ";std::string product;std::cin >> product;std::cout << "请输入数量: ";int quantity;std::cin >> quantity;simpleUI.orderProduct(product, quantity);}break;default:std::cout << "❌ 无效选择" << std::endl;}}void systemStatus() {std::cout << "\n📊 系统状态" << std::endl;std::cout << "===========" << std::endl;homeTheater_->getStatus();smartFacade_->adaptiveOptimization();}
};int main() {testFacadePattern();// 运行智能家居控制系统示例SmartHomeControlSystem smartHome;smartHome.run();return 0;
}

外观模式的武学心得

适用场景
  • 复杂子系统：需要为复杂的子系统提供一个简单的接口时
  • 分层架构：需要构建分层结构的系统，减少层与层之间的依赖时
  • 客户端简化：客户端与多个子系统之间存在很多依赖关系时
  • 入口统一：需要为子系统提供一个统一的入口点，以便集中管理时
优点
  • 简化使用：让客户端使用子系统变得更加简单
  • 解耦：将客户端与子系统解耦，提高子系统的独立性和可移植性
  • 易于维护：将复杂逻辑封装在外观类中，便于维护和修改
  • 层次清晰：为复杂的子系统提供一个清晰的层次结构
缺点
  • 不符合开闭原则：增加新的子系统可能需要修改外观类
  • 过度封装：可能隐藏了客户端需要的高级功能
  • 单点故障：外观类可能成为系统的单点故障

武林高手的点评

Decorator 赞叹道：“Facade 兄的简化之道确实高明！能够如此优雅地隐藏复杂系统的细节，这在构建易用系统时确实无人能及。”

Adapter 也点头称赞：“Facade 兄专注于简化复杂系统的接口，而我更关注接口的兼容转换。我们都在改善系统的可用性，但角度不同。”

Facade 谦虚回应：“诸位过奖了。每个模式都有其适用场景。在需要简化复杂系统接口时，我的外观模式确实能发挥重要作用。但在需要动态扩展功能时，Decorator 兄的方法更加合适。”

下章预告

在Facade展示完他的简化艺术后，Flyweight 身形淡薄如纸、几乎透明地走出，他悄无声息地出现，细声细语地说话。

“Facade 兄的接口简化确实优雅，但在处理大量细粒度对象时，内存效率才是关键。” Flyweight 细声说道，“下一章，我将展示如何通过享元模式极致地节省资源，支持海量对象！”

架构老人满意地点头：“善！内存效率确实是性能优化的关键。下一章，就请 Flyweight 展示他的资源共享之道！”

欲知 Flyweight 如何通过享元模式实现极致的内存优化，且听下回分解！

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