# 策略模式知识库

pattern:
  id: "strategy-pattern"
  name: "策略模式"
  category: "行为型模式"
  description: "定义一系列算法，把它们封装起来，并使它们可互相替换，让算法独立于使用它的客户而变化"

# 模式结构
structure:
  participants:
    - name: "Strategy"
      role: "策略接口"
      description: "定义所有支持的算法的公共接口"
    - name: "ConcreteStrategy"
      role: "具体策略"
      description: "实现策略接口的具体算法"
    - name: "Context"
      role: "上下文"
      description: "维护对策略对象的引用"

# 项目中的应用
applications:
  - module: "pay"
    location: "PayClient接口及其实现"
    purpose: "支持多渠道支付"
    code_path: "yudao-module-pay/.../pay/core/client/PayClient.java"
    strategies:
      - name: "AlipayQrPayClient"
        description: "支付宝扫码支付"
      - name: "AlipayAppPayClient"
        description: "支付宝App支付"
      - name: "WxNativePayClient"
        description: "微信Native支付"
      - name: "WxAppPayClient"
        description: "微信App支付"
    implementation: |
      public interface PayClient<Config extends PayClientConfig> {
          Long getId();
          PayOrderRespDTO unifiedOrder(PayOrderUnifiedReqDTO reqDTO);
          PayRefundRespDTO unifiedRefund(PayRefundUnifiedReqDTO reqDTO);
      }

  - module: "infra/sms"
    location: "SmsClient接口及其实现"
    purpose: "支持多渠道短信发送"
    strategies:
      - name: "AliyunSmsClient"
        description: "阿里云短信"
      - name: "TencentSmsClient"
        description: "腾讯云短信"
      - name: "HuaweiSmsClient"
        description: "华为云短信"
      - name: "QiniuSmsClient"
        description: "七牛云短信"

  - module: "ai"
    location: "ChatModel接口及其实现"
    purpose: "支持多AI模型"
    strategies:
      - name: "OpenAIChatModel"
        description: "OpenAI聊天模型"
      - name: "BaiduChatModel"
        description: "百度文心一言"
      - name: "ZhipuChatModel"
        description: "智谱AI"
      - name: "TongyiChatModel"
        description: "阿里通义千问"

# 使用场景
scenarios:
  - "需要在运行时选择算法"
  - "有多个类只在行为上有差异"
  - "需要动态切换算法"
  - "需要隐藏算法实现细节"

# 优点
advantages:
  - "算法可自由切换"
  - "避免使用多重条件判断"
  - "易于扩展新策略"
  - "符合开闭原则"

# 缺点
disadvantages:
  - "客户端需要了解所有策略"
  - "策略过多时类数量增加"

# 与工厂模式配合
factory_integration:
  description: "策略模式通常与工厂模式配合使用，由工厂创建具体策略实例"
  example:
    factory: "PayClientFactory"
    purpose: "根据渠道配置创建对应的PayClient实例"
    code: |
      // 通过工厂获取策略
      PayClient client = payClientFactory.getPayClient(channelId);
      // 使用策略
      PayOrderRespDTO response = client.unifiedOrder(reqDTO);

# 扩展指南
extension_guide:
  title: "如何新增策略"
  steps:
    - step: 1
      action: "创建策略实现类"
      description: "实现策略接口"
    - step: 2
      action: "定义配置类"
      description: "如果需要配置参数"
    - step: 3
      action: "修改工厂"
      description: "在工厂中添加创建分支"
    - step: 4
      action: "添加枚举"
      description: "如果需要类型枚举"

  example:
    title: "新增短信渠道"
    code: |
      // 1. 创建实现类
      public class XxxSmsClient extends AbstractSmsClient {
          @Override
          protected void doInit() { ... }

          @Override
          public SmsSendResultDTO sendSms(SmsSendMessageDTO message) { ... }
      }

      // 2. 添加渠道枚举
      public enum SmsChannelEnum {
          XXX(10, "XXX短信");
      }

      // 3. 修改工厂创建逻辑
      case XXX: return new XxxSmsClient(properties);