一、策略模式：灵活切换支付方式
场景需求
系统需要支持支付宝、微信支付、银联等多种支付渠道，且可能随时新增支付方式。
模式实现
- 定义支付策略接口
public interface IPaymentStrategy
{void ProcessPayment(decimal amount, string currency);
}
- 实现具体支付策略类
// 支付宝策略
public class AlipayStrategy : IPaymentStrategy
{public void ProcessPayment(decimal amount, string currency){Console.WriteLine($"支付宝支付：{amount}{currency}");// 调用支付宝SDK实现}
}// 微信支付策略（实现类似）
public class WechatPayStrategy : IPaymentStrategy { /*...*/ }
- 创建支付上下文类
public class PaymentContext
{private IPaymentStrategy _strategy;public void SetStrategy(IPaymentStrategy strategy) => _strategy = strategy;public void ExecutePayment(decimal amount, string currency) {_strategy.ProcessPayment(amount, currency);}
}
二、装饰器模式：动态扩展支付功能
场景需求
为支付流程添加日志记录、风控验证等附加功能。
模式实现
public abstract class PaymentDecorator : IPaymentStrategy
{protected IPaymentStrategy _strategy;public PaymentDecorator(IPaymentStrategy strategy){_strategy = strategy;}public virtual void ProcessPayment(decimal amount, string currency){_strategy.ProcessPayment(amount, currency);}
}// 日志装饰器
public class LoggingDecorator : PaymentDecorator
{public LoggingDecorator(IPaymentStrategy strategy) : base(strategy) {}public override void ProcessPayment(decimal amount, string currency){Console.WriteLine($"[LOG] 支付请求：{amount}{currency}");base.ProcessPayment(amount, currency);}
}public class RiskCheckDecorator : PaymentDecorator
{public RiskCheckDecorator(IPaymentStrategy strategy) : base(strategy) {}public override void ProcessPayment(decimal amount, string currency){Console.WriteLine("[RISK] 风控验证中...");base.ProcessPayment(amount, currency);}
}// 使用示例
var payment = new LoggingDecorator(new RiskCheckDecorator(new AlipayStrategy()));
payment.ProcessPayment(100, "CNY");
三、工厂模式：统一支付对象创建
场景需求
根据配置参数动态创建支付策略实例。
模式实现
public class PaymentFactory
{public static IPaymentStrategy Create(string paymentType){switch (paymentType.ToLower()){case "alipay":return new AlipayStrategy();case "wechat":return new WechatPayStrategy();case "unionpay":return new UnionPayStrategy();default:throw new ArgumentException("不支持的支付方式");}}
}// 调用示例
var strategy = PaymentFactory.Create("alipay");
strategy.ProcessPayment(200, "USD");
四、责任链模式：支付流程处理
场景需求
处理支付请求时需要依次执行：参数校验 → 风控检查 → 实际支付 → 结果通知。
模式实现
public abstract class PaymentHandler
{protected PaymentHandler _nextHandler;public void SetNext(PaymentHandler handler) => _nextHandler = handler;public abstract void Handle(PaymentRequest request);
}// 参数校验处理器
public class ValidationHandler : PaymentHandler
{public override void Handle(PaymentRequest request){if (string.IsNullOrEmpty(request.OrderId))throw new ArgumentException("订单号无效");_nextHandler?.Handle(request);}
}// 构建处理链
var chain = new ValidationHandler();
chain.SetNext(new RiskCheckHandler()).SetNext(new PaymentProcessorHandler()).SetNext(new NotificationHandler());
chain.Handle(request);
五、综合应用示例
- 定义支付策略接口
public interface IPaymentStrategy
{void ProcessPayment(decimal amount, string currency);
}
- 实现具体支付策略类
// 支付宝策略
public class AlipayStrategy : IPaymentStrategy
{public void ProcessPayment(decimal amount, string currency){Console.WriteLine($"支付宝支付：{amount}{currency}");// 调用支付宝SDK实现}
}// 微信支付策略（实现类似）
public class WechatPayStrategy : IPaymentStrategy { /*...*/ }// 银联支付策略（实现类似）
public class UnionPayStrategy : IPaymentStrategy { /*...*/ }
- 创建支付请求类
public class PaymentFactory
{public static IPaymentStrategy Create(string paymentType){switch (paymentType.ToLower()){case "alipay":return new AlipayStrategy();case "wechat":return new WechatPayStrategy();case "unionpay":return new UnionPayStrategy();default:throw new ArgumentException("不支持的支付方式");}}
}
- 创建支付装饰类
public abstract class PaymentDecorator : IPaymentStrategy
{protected IPaymentStrategy _strategy;public PaymentDecorator(IPaymentStrategy strategy){_strategy = strategy;}public virtual void ProcessPayment(decimal amount, string currency){_strategy.ProcessPayment(amount, currency);}
}// 日志装饰器
public class LoggingDecorator : PaymentDecorator
{public LoggingDecorator(IPaymentStrategy strategy) : base(strategy) {}public override void ProcessPayment(decimal amount, string currency){Console.WriteLine($"[LOG] 支付请求：{amount}{currency}");base.ProcessPayment(amount, currency);}
}
- 创建支付上下文类
public class PaymentContext
{private IPaymentStrategy _strategy;public void SetStrategy(IPaymentStrategy strategy) => _strategy = strategy;public void ExecutePayment(decimal amount, string currency) {new LoggingDecorator(_strategy).ProcessPayment(amount, currency);}
}
- 创建支付处理链类
public abstract class PaymentHandler
{protected PaymentHandler _nextHandler;public void SetNext(PaymentHandler handler) => _nextHandler = handler;public abstract void Handle(PaymentRequest request);
}// 参数校验处理器
public class ValidationHandler : PaymentHandler
{public override void Handle(PaymentRequest request){if (string.IsNullOrEmpty(request.OrderId))throw new ArgumentException("订单号无效");_nextHandler?.Handle(request);}
}// 风控检查处理器
public class RiskCheckHandler : PaymentHandler
{public override void Handle(PaymentRequest request){Console.WriteLine("[RISK] 风控验证中...");_nextHandler?.Handle(request);}
}// 支付结果通知处理器
public class NotificationHandler : PaymentHandler
{public override void Handle(PaymentRequest request){Console.WriteLine($"支付结果通知：{request.OrderId}");_nextHandler?.Handle(request);}
}// 实际支付处理器
public class PaymentProcessorHandler : PaymentHandler
{public override void Handle(PaymentRequest request){Console.WriteLine($"[PAYMENT] 实际支付：{request.Amount}{request.Currency}");var strategy = PaymentFactory.Create(request.PaymentType);PaymentContext context = new PaymentContext();context.SetStrategy(strategy);context.ExecutePayment(request.Amount, request.Currency);_nextHandler?.Handle(request);}
}// 构建处理链
var chain = new ValidationHandler();
chain.SetNext(new RiskCheckHandler()).SetNext(new PaymentProcessorHandler()).SetNext(new NotificationHandler());
chain.Handle(request);
