当前位置： 首页 > news >正文

第十四章：运筹帷幄，随机应变——Strategy的策略艺术

news 2025/10/6 18:21:31

第十四章：运筹帷幄，随机应变——Strategy的策略艺术

风云再起，策略大师登场

在Observer展示完他那精妙的观察艺术后，Strategy身背多种兵器，从容不迫地走出。他的腰间挂满了各式各样的武器，每种武器都代表着不同的算法策略。

"Observer兄的通知机制确实精妙，"Strategy沉稳地说道，“但在算法选择和策略切换方面，需要更加灵活的应对方式。诸位请看——”

Strategy随手取下腰间的一柄长剑和一把短刀，在手中自如切换：“我的策略模式，专为解决算法族的定义和使用问题而生！我允许在运行时选择算法，让算法可以独立于使用它的客户端变化！”

架构老人眼中闪过赞许之色：“善！Strategy，就请你为大家展示这策略艺术的精妙所在。”

策略模式的核心要义

Strategy面向众人，开始阐述他的武学真谛：

“在我的策略模式中，主要包含三个核心角色：”

“Strategy（策略）：定义所有支持的算法的公共接口。”

“ConcreteStrategy（具体策略）：实现了策略接口的具体算法类。”

“Context（上下文）：维护一个策略对象的引用，通过策略接口与之通信。”

"其精妙之处在于，"Strategy继续道，“客户端不需要知道具体算法的实现细节，只需要通过统一的策略接口来使用算法。这样，我们可以随时替换算法，而无需修改客户端的代码！”

C++实战：支付系统设计

"且让我以一个支付系统为例，展示策略模式的实战应用。"Strategy说着，手中凝聚出一道道代码流光。

基础框架搭建

首先，Strategy定义了支付策略接口：

#include <iostream>
#include <vector>
#include <string>
#include <memory>
#include <algorithm>
#include <map>
#include <iomanip>
#include <sstream>
#include <random>
#include <thread>
#include <chrono>
#include <cmath>// 支付信息结构
struct PaymentInfo {double amount;std::string currency;std::string orderId;std::string customerId;std::chrono::system_clock::time_point timestamp;PaymentInfo(double amt, const std::string& curr = "USD", const std::string& order = "", const std::string& customer = ""): amount(amt), currency(curr), orderId(order), customerId(customer),timestamp(std::chrono::system_clock::now()) {}std::string toString() const {auto time = std::chrono::system_clock::to_time_t(timestamp);std::string timeStr = std::ctime(&time);timeStr.pop_back();std::stringstream ss;ss << "订单: " << orderId << " | 客户: " << customerId << " | 金额: " << std::fixed << std::setprecision(2) << amount << " " << currency<< " | 时间: " << timeStr;return ss.str();}
};// 支付结果结构
struct PaymentResult {bool success;std::string transactionId;std::string message;double fee;double finalAmount;PaymentResult(bool s, const std::string& tid = "", const std::string& msg = "", double f = 0.0, double final = 0.0): success(s), transactionId(tid), message(msg), fee(f), finalAmount(final) {}std::string toString() const {std::stringstream ss;ss << (success ? "✅" : "❌") << " " << message;if (success) {ss << " | 交易ID: " << transactionId << " | 手续费: " << std::fixed << std::setprecision(2) << fee<< " | 实收: " << finalAmount;}return ss.str();}
};// 策略接口：支付策略
class PaymentStrategy {
public:virtual ~PaymentStrategy() = default;virtual PaymentResult processPayment(const PaymentInfo& paymentInfo) = 0;virtual std::string getStrategyName() const = 0;virtual double calculateFee(double amount) const = 0;virtual bool validatePayment(const PaymentInfo& paymentInfo) const = 0;
};

具体策略实现

Strategy展示了多种支付方式的具体实现：

// 具体策略：信用卡支付
class CreditCardPayment : public PaymentStrategy {
private:std::string processorName_;double feeRate_;public:CreditCardPayment(const std::string& processor = "Stripe", double feeRate = 0.029): processorName_(processor), feeRate_(feeRate) {std::cout << "💳 创建信用卡支付策略: " << processorName_ << std::endl;}PaymentResult processPayment(const PaymentInfo& paymentInfo) override {std::cout << "🔒 使用 " << processorName_ << " 处理信用卡支付..." << std::endl;// 模拟处理时间std::this_thread::sleep_for(std::chrono::milliseconds(800));if (!validatePayment(paymentInfo)) {return PaymentResult(false, "", "信用卡支付验证失败");}double fee = calculateFee(paymentInfo.amount);double finalAmount = paymentInfo.amount - fee;// 生成交易IDstd::string transactionId = "CC_" + std::to_string(rand() % 1000000);std::cout << "✅ 信用卡支付成功!" << std::endl;return PaymentResult(true, transactionId, "信用卡支付成功 - " + processorName_, fee, finalAmount);}std::string getStrategyName() const override {return "信用卡支付 (" + processorName_ + ")";}double calculateFee(double amount) const override {return amount * feeRate_ + 0.30; // 固定费用 + 百分比}bool validatePayment(const PaymentInfo& paymentInfo) const override {if (paymentInfo.amount <= 0) {std::cout << "❌ 金额必须大于0" << std::endl;return false;}if (paymentInfo.amount > 10000.0) {std::cout << "❌ 单笔支付金额不能超过10000" << std::endl;return false;}return true;}void setFeeRate(double rate) {feeRate_ = rate;std::cout << "💰 设置信用卡费率: " << rate * 100 << "%" << std::endl;}
};// 具体策略：PayPal支付
class PayPalPayment : public PaymentStrategy {
private:std::string email_;double feeRate_;public:PayPalPayment(const std::string& email = "merchant@example.com", double feeRate = 0.024): email_(email), feeRate_(feeRate) {std::cout << "🔵 创建PayPal支付策略: " << email_ << std::endl;}PaymentResult processPayment(const PaymentInfo& paymentInfo) override {std::cout << "🌐 通过PayPal处理支付..." << std::endl;// 模拟网络请求时间std::this_thread::sleep_for(std::chrono::milliseconds(1200));if (!validatePayment(paymentInfo)) {return PaymentResult(false, "", "PayPal支付验证失败");}double fee = calculateFee(paymentInfo.amount);double finalAmount = paymentInfo.amount - fee;// 生成交易IDstd::string transactionId = "PP_" + std::to_string(rand() % 1000000);std::cout << "✅ PayPal支付成功!" << std::endl;return PaymentResult(true, transactionId, "PayPal支付成功", fee, finalAmount);}std::string getStrategyName() const override {return "PayPal支付 (" + email_ + ")";}double calculateFee(double amount) const override {return amount * feeRate_;}bool validatePayment(const PaymentInfo& paymentInfo) const override {if (paymentInfo.amount < 1.0) {std::cout << "❌ PayPal支付金额不能少于1元" << std::endl;return false;}return true;}
};// 具体策略：加密货币支付
class CryptoPayment : public PaymentStrategy {
private:std::string cryptocurrency_;double networkFee_;public:CryptoPayment(const std::string& crypto = "Bitcoin", double networkFee = 2.0): cryptocurrency_(crypto), networkFee_(networkFee) {std::cout << "₿  创建加密货币支付策略: " << cryptocurrency_ << std::endl;}PaymentResult processPayment(const PaymentInfo& paymentInfo) override {std::cout << "⛓️  处理 " << cryptocurrency_ << " 支付..." << std::endl;// 模拟区块链确认时间std::this_thread::sleep_for(std::chrono::milliseconds(2000));if (!validatePayment(paymentInfo)) {return PaymentResult(false, "", "加密货币支付验证失败");}double fee = calculateFee(paymentInfo.amount);double finalAmount = paymentInfo.amount - fee;// 生成交易哈希std::string transactionId = crypto_ + "_" + generateTransactionHash();std::cout << "✅ " << cryptocurrency_ << " 支付成功!" << std::endl;return PaymentResult(true, transactionId, cryptocurrency_ + " 支付成功", fee, finalAmount);}std::string getStrategyName() const override {return cryptocurrency_ + " 支付";}double calculateFee(double amount) const override {return networkFee_; // 固定网络费用}bool validatePayment(const PaymentInfo& paymentInfo) const override {if (paymentInfo.amount <= 0) {std::cout << "❌ 金额必须大于0" << std::endl;return false;}return true;}private:std::string generateTransactionHash() const {const char chars[] = "0123456789abcdef";std::string hash;for (int i = 0; i < 64; ++i) {hash += chars[rand() % 16];}return hash;}std::string crypto_ = "BTC"; // 简化表示
};// 具体策略：银行转账
class BankTransferPayment : public PaymentStrategy {
private:std::string bankName_;double fixedFee_;public:BankTransferPayment(const std::string& bank = "中国银行", double fixedFee = 1.5): bankName_(bank), fixedFee_(fixedFee) {std::cout << "🏦 创建银行转账策略: " << bankName_ << std::endl;}PaymentResult processPayment(const PaymentInfo& paymentInfo) override {std::cout << "💼 处理 " << bankName_ << " 银行转账..." << std::endl;// 模拟银行处理时间std::this_thread::sleep_for(std::chrono::milliseconds(1500));if (!validatePayment(paymentInfo)) {return PaymentResult(false, "", "银行转账验证失败");}double fee = calculateFee(paymentInfo.amount);double finalAmount = paymentInfo.amount - fee;// 生成交易IDstd::string transactionId = "BT_" + std::to_string(rand() % 1000000);std::cout << "✅ 银行转账成功!" << std::endl;return PaymentResult(true, transactionId, bankName_ + " 银行转账成功", fee, finalAmount);}std::string getStrategyName() const override {return bankName_ + " 银行转账";}double calculateFee(double amount) const override {return fixedFee_; // 固定手续费}bool validatePayment(const PaymentInfo& paymentInfo) const override {if (paymentInfo.amount < 10.0) {std::cout << "❌ 银行转账金额不能少于10元" << std::endl;return false;}if (paymentInfo.amount > 50000.0) {std::cout << "❌ 单笔银行转账不能超过50000元" << std::endl;return false;}return true;}
};

上下文实现

Strategy创建了支付处理器上下文：

// 上下文：支付处理器
class PaymentProcessor {
private:std::unique_ptr<PaymentStrategy> strategy_;std::string processorName_;std::vector<PaymentResult> paymentHistory_;public:PaymentProcessor(const std::string& name = "通用支付处理器") : processorName_(name) {std::cout << "🔄 创建支付处理器: " << processorName_ << std::endl;}~PaymentProcessor() {std::cout << "🗑️  销毁支付处理器: " << processorName_ << std::endl;}void setStrategy(std::unique_ptr<PaymentStrategy> strategy) {strategy_ = std::move(strategy);std::cout << "🎯 " << processorName_ << " 设置策略: " << strategy_->getStrategyName() << std::endl;}PaymentResult processPayment(const PaymentInfo& paymentInfo) {if (!strategy_) {std::cout << "❌ 未设置支付策略!" << std::endl;return PaymentResult(false, "", "未设置支付策略");}std::cout << "\n💸 " << processorName_ << " 开始处理支付..." << std::endl;std::cout << "📄 " << paymentInfo.toString() << std::endl;auto startTime = std::chrono::high_resolution_clock::now();PaymentResult result = strategy_->processPayment(paymentInfo);auto endTime = std::chrono::high_resolution_clock::now();auto duration = std::chrono::duration_cast<std::chrono::milliseconds>(endTime - startTime);std::cout << "⏱️  处理耗时: " << duration.count() << "ms" << std::endl;// 记录支付历史paymentHistory_.push_back(result);std::cout << "📊 支付结果: " << result.toString() << std::endl;return result;}std::string getCurrentStrategyName() const {return strategy_ ? strategy_->getStrategyName() : "未设置策略";}void showPaymentHistory() const {std::cout << "\n📜 " << processorName_ << " 支付历史 (" << paymentHistory_.size() << " 笔):" << std::endl;int successCount = 0;double totalAmount = 0.0;double totalFees = 0.0;for (size_t i = 0; i < paymentHistory_.size(); ++i) {const auto& result = paymentHistory_[i];std::cout << "  " << (i + 1) << ". " << result.toString() << std::endl;if (result.success) {successCount++;totalAmount += result.finalAmount;totalFees += result.fee;}}std::cout << "\n📈 统计摘要:" << std::endl;std::cout << "   成功交易: " << successCount << "/" << paymentHistory_.size() << std::endl;std::cout << "   总实收金额: $" << std::fixed << std::setprecision(2) << totalAmount << std::endl;std::cout << "   总手续费: $" << totalFees << std::endl;if (successCount > 0) {std::cout << "   平均手续费率: " << std::fixed << std::setprecision(2) << (totalFees / (totalAmount + totalFees) * 100) << "%" << std::endl;}}void clearHistory() {paymentHistory_.clear();std::cout << "🧹 清空支付历史" << std::endl;}std::string getProcessorInfo() const {std::stringstream ss;ss << processorName_ << " [策略: " << getCurrentStrategyName() << ", 历史记录: " << paymentHistory_.size() << " 笔]";return ss.str();}
};

UML 武功秘籍图

uses
«interface»
PaymentStrategy
+processPayment(PaymentInfo) : PaymentResult
+getStrategyName() : string
+calculateFee(double) : double
+validatePayment(PaymentInfo) : bool
CreditCardPayment
-string processorName_
-double feeRate_
+processPayment(PaymentInfo) : PaymentResult
+getStrategyName() : string
+calculateFee(double) : double
+validatePayment(PaymentInfo) : bool
+setFeeRate(double) : void
PayPalPayment
-string email_
-double feeRate_
+processPayment(PaymentInfo) : PaymentResult
+getStrategyName() : string
+calculateFee(double) : double
+validatePayment(PaymentInfo) : bool
CryptoPayment
-string cryptocurrency_
-double networkFee_
+processPayment(PaymentInfo) : PaymentResult
+getStrategyName() : string
+calculateFee(double) : double
+validatePayment(PaymentInfo) : bool
-generateTransactionHash() : string
BankTransferPayment
-string bankName_
-double fixedFee_
+processPayment(PaymentInfo) : PaymentResult
+getStrategyName() : string
+calculateFee(double) : double
+validatePayment(PaymentInfo) : bool
PaymentProcessor
-unique_ptr<PaymentStrategy> strategy_
-string processorName_
-vector<PaymentResult> paymentHistory_
+setStrategy(unique_ptr<PaymentStrategy>) : void
+processPayment(PaymentInfo) : PaymentResult
+getCurrentStrategyName() : string
+showPaymentHistory() : void
+clearHistory() : void
+getProcessorInfo() : string

实战演练：高级策略系统

Strategy继续展示更复杂的策略模式应用：

// 策略工厂：创建各种支付策略
class PaymentStrategyFactory {
public:static std::unique_ptr<PaymentStrategy> createCreditCardStrategy(const std::string& processor = "Stripe", double feeRate = 0.029) {return std::make_unique<CreditCardPayment>(processor, feeRate);}static std::unique_ptr<PaymentStrategy> createPayPalStrategy(const std::string& email = "merchant@example.com", double feeRate = 0.024) {return std::make_unique<PayPalPayment>(email, feeRate);}static std::unique_ptr<PaymentStrategy> createCryptoStrategy(const std::string& crypto = "Bitcoin", double networkFee = 2.0) {return std::make_unique<CryptoPayment>(crypto, networkFee);}static std::unique_ptr<PaymentStrategy> createBankTransferStrategy(const std::string& bank = "中国银行", double fixedFee = 1.5) {return std::make_unique<BankTransferPayment>(bank, fixedFee);}static std::unique_ptr<PaymentStrategy> createStrategyFromConfig(const std::string& strategyType, const std::map<std::string, std::string>& config) {if (strategyType == "credit_card") {std::string processor = config.count("processor") ? config.at("processor") : "Stripe";double feeRate = config.count("fee_rate") ? std::stod(config.at("fee_rate")) : 0.029;return createCreditCardStrategy(processor, feeRate);}else if (strategyType == "paypal") {std::string email = config.count("email") ? config.at("email") : "merchant@example.com";double feeRate = config.count("fee_rate") ? std::stod(config.at("fee_rate")) : 0.024;return createPayPalStrategy(email, feeRate);}else if (strategyType == "crypto") {std::string crypto = config.count("crypto") ? config.at("crypto") : "Bitcoin";double networkFee = config.count("network_fee") ? std::stod(config.at("network_fee")) : 2.0;return createCryptoStrategy(crypto, networkFee);}else if (strategyType == "bank_transfer") {std::string bank = config.count("bank") ? config.at("bank") : "中国银行";double fixedFee = config.count("fixed_fee") ? std::stod(config.at("fixed_fee")) : 1.5;return createBankTransferStrategy(bank, fixedFee);}throw std::invalid_argument("未知的策略类型: " + strategyType);}
};// 策略管理器：管理多个策略和上下文
class StrategyManager {
private:std::map<std::string, std::unique_ptr<PaymentProcessor>> processors_;std::map<std::string, std::unique_ptr<PaymentStrategy>> availableStrategies_;public:StrategyManager() {std::cout << "👨‍💼 创建策略管理器" << std::endl;initializeDefaultStrategies();}~StrategyManager() {std::cout << "🗑️  销毁策略管理器" << std::endl;}void initializeDefaultStrategies() {// 初始化可用的策略availableStrategies_["credit_card_stripe"] = PaymentStrategyFactory::createCreditCardStrategy("Stripe", 0.029);availableStrategies_["credit_card_paypal"] = PaymentStrategyFactory::createCreditCardStrategy("PayPal", 0.034);availableStrategies_["paypal"] = PaymentStrategyFactory::createPayPalStrategy("merchant@example.com", 0.024);availableStrategies_["bitcoin"] = PaymentStrategyFactory::createCryptoStrategy("Bitcoin", 2.0);availableStrategies_["ethereum"] = PaymentStrategyFactory::createCryptoStrategy("Ethereum", 1.5);availableStrategies_["bank_transfer"] = PaymentStrategyFactory::createBankTransferStrategy("中国银行", 1.5);std::cout << "✅ 初始化 " << availableStrategies_.size() << " 个默认策略" << std::endl;}void createProcessor(const std::string& processorName) {processors_[processorName] = std::make_unique<PaymentProcessor>(processorName);std::cout << "🆕 创建支付处理器: " << processorName << std::endl;}void setProcessorStrategy(const std::string& processorName, const std::string& strategyKey) {auto processorIt = processors_.find(processorName);auto strategyIt = availableStrategies_.find(strategyKey);if (processorIt != processors_.end() && strategyIt != availableStrategies_.end()) {// 克隆策略（因为同一个策略可能被多个处理器使用）auto clonedStrategy = cloneStrategy(strategyKey);processorIt->second->setStrategy(std::move(clonedStrategy));} else {std::cout << "❌ 找不到处理器或策略: " << processorName << "/" << strategyKey << std::endl;}}void addCustomStrategy(const std::string& key, std::unique_ptr<PaymentStrategy> strategy) {availableStrategies_[key] = std::move(strategy);std::cout << "🆕 添加自定义策略: " << key << std::endl;}PaymentResult processPaymentWith(const std::string& processorName, const PaymentInfo& paymentInfo) {auto it = processors_.find(processorName);if (it != processors_.end()) {return it->second->processPayment(paymentInfo);}return PaymentResult(false, "", "找不到处理器: " + processorName);}void listAllProcessors() const {std::cout << "\n📋 所有支付处理器 (" << processors_.size() << " 个):" << std::endl;for (const auto& pair : processors_) {std::cout << "   • " << pair.second->getProcessorInfo() << std::endl;}}void listAllStrategies() const {std::cout << "\n🎯 所有可用策略 (" << availableStrategies_.size() << " 个):" << std::endl;for (const auto& pair : availableStrategies_) {std::cout << "   • " << pair.first << ": " << pair.second->getStrategyName() << std::endl;}}void showProcessorHistory(const std::string& processorName) const {auto it = processors_.find(processorName);if (it != processors_.end()) {it->second->showPaymentHistory();} else {std::cout << "❌ 找不到处理器: " << processorName << std::endl;}}private:std::unique_ptr<PaymentStrategy> cloneStrategy(const std::string& strategyKey) const {auto it = availableStrategies_.find(strategyKey);if (it != availableStrategies_.end()) {// 根据策略类型创建新的实例if (auto creditCard = dynamic_cast<CreditCardPayment*>(it->second.get())) {return std::make_unique<CreditCardPayment>(*creditCard);}else if (auto paypal = dynamic_cast<PayPalPayment*>(it->second.get())) {return std::make_unique<PayPalPayment>(*paypal);}else if (auto crypto = dynamic_cast<CryptoPayment*>(it->second.get())) {return std::make_unique<CryptoPayment>(*crypto);}else if (auto bank = dynamic_cast<BankTransferPayment*>(it->second.get())) {return std::make_unique<BankTransferPayment>(*bank);}}return nullptr;}
};

策略模式的招式解析

招式一：动态策略选择

// 智能策略选择器：根据条件自动选择最佳策略
class SmartStrategySelector {
public:static std::string selectBestStrategy(double amount, const std::string& currency, const std::string& customerRegion) {std::cout << "\n🤔 智能选择策略..." << std::endl;std::cout << "   金额: " << amount << " " << currency << std::endl;std::cout << "   客户地区: " << customerRegion << std::endl;// 基于规则的策略选择if (amount < 1.0) {std::cout << "   💡 推荐: PayPal (小额支付)" << std::endl;return "paypal";}else if (amount > 10000.0) {std::cout << "   💡 推荐: 银行转账 (大额支付)" << std::endl;return "bank_transfer";}else if (customerRegion == "国际" || customerRegion == "海外") {std::cout << "   💡 推荐: 加密货币 (国际支付)" << std::endl;return "bitcoin";}else if (amount <= 1000.0) {std::cout << "   💡 推荐: Stripe信用卡 (常规支付)" << std::endl;return "credit_card_stripe";}else {std::cout << "   💡 推荐: PayPal信用卡 (中等金额)" << std::endl;return "credit_card_paypal";}}static double calculateOptimalFee(double amount, const std::string& strategyKey) {// 创建临时策略来计算费用auto tempStrategy = PaymentStrategyFactory::createStrategyFromConfig(strategyKey, {});return tempStrategy->calculateFee(amount);}
};// 自适应支付处理器
class AdaptivePaymentProcessor {
private:StrategyManager& strategyManager_;std::string processorName_;public:AdaptivePaymentProcessor(StrategyManager& manager, const std::string& name): strategyManager_(manager), processorName_(name) {std::cout << "🧠 创建自适应支付处理器: " << processorName_ << std::endl;}PaymentResult processPaymentAdaptive(const PaymentInfo& paymentInfo) {std::cout << "\n🎯 " << processorName_ << " 开始自适应支付处理..." << std::endl;// 智能选择最佳策略std::string bestStrategy = SmartStrategySelector::selectBestStrategy(paymentInfo.amount, paymentInfo.currency, "国内"); //
http://www.dtcms.com/a/447869.html

相关文章：

  • 网站内页是什么开发公司工程部
  • 找段子的各大网站现在新手做电商能做好吗
  • [进化算法]基于EA方案的大模型剪枝
  • 医院网站制作多少钱哈尔滨信息网官网
  • 苏州化妆品网站建设做网站服务器是必须购买的吗
  • 手机网站如何建站企业建设网站 意义何在
  • 建设工程信息哪个网站有详细信息如何做网站流量
  • 网站开发工程师是什么黄岛网站建设哪家好
  • 网站建设公司一站通系统简单网站开发一定要用框架吗
  • 大庆建设工程交易中心网站做cms网站步骤
  • 无锡企业网站制作策划成都APP 微网站开发
  • 网站建设前准备男生做网站运营的前景
  • 张店网站建设定制口碑好的专业网站建设
  • 企业做网站报价信用平台网站建设建议
  • 潍坊网站建设公司腾讯企业邮箱浙江服务中心
  • 网站seo测评网站开发验收报告
  • wordpress做旅游网站太原推广型网站建设
  • 网站没备案能访问吗优良网站
  • 有没有专门做本子的网站实惠高端网站设计品牌
  • 杭州网站建设提供商网站怎么做接口
  • 网站后台管理系统进不去怎么办政务公开网站建设工作情况汇报
  • 自己做网站 怎么赚钱飞天云服务器
  • 常德网站建教人做甜品的网站
  • 昆明网站建设推广免费的韩国网站服务器
  • 云南网站建设企业推荐网络营销专员的就业前景
  • 做一家网站费用吗wordpress面包学
  • 惠州公司网站建设dw网页制作模板源代码
  • 怎么做投票网站宁波做网站的公司哪家好
  • 交易类网站建设费用dwcc如何做网站
  • 烟台seo做的好的网站wordpress 翻译不起作用