微服务架构模式完全指南：设计模式与实战

gRPC

syntax = "proto3";

service OrderService { rpc CreateOrder(CreateOrderRequest) returns (Order); rpc GetOrder(GetOrderRequest) returns (Order); }

message Order { string id = 1; string user_id = 2; repeated OrderItem items = 3; }

### 3.2 异步通信

```yaml
# RabbitMQ 消息
# order.created
{
  "event": "order.created",
  "orderId": "123",
  "userId": "456",
  "total": 100.00,
  "timestamp": "2024-01-01T10:00:00Z"
}

四、服务发现

4.1 Consul

# docker-compose.yml
services:
  consul:
    image: consul
    ports:
      - "8500:8500"
    command: agent -server -ui -bootstrap-expect=1 -client=0.0.0.0

4.2 Spring Cloud Netflix

# application.yml
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true

五、容错处理

5.1 熔断器

┌─────────────────────────────────────────────────────────────┐
│                    熔断器状态                                │
│                                                              │
│  Closed (关闭) ──▶ 故障 ──▶ Open (打开)                   │
│      ▲                              │                       │
│      │                              ▼                       │
│      └─────── 恢复 ────────── Half-Open (半开)            │
│                                                              │
│  关闭: 正常请求                                              │
│  打开: 快速失败                                              │
│  半开: 探测恢复                                              │
└─────────────────────────────────────────────────────────────┘

5.2 Resilience4j

// 熔断器
CircuitBreakerConfig config = CircuitBreakerConfig.custom()
    .failureRateThreshold(50)
    .waitDurationInOpenState(Duration.ofSeconds(10))
    .slidingWindowSize(10)
    .build();

CircuitBreaker circuitBreaker = CircuitBreaker.of("backendService", config);

// 使用
Decorator.decorateSupplier(supplier, circuitBreaker)
    .get();

5.3 重试

RetryConfig config = RetryConfig.custom()
    .maxAttempts(3)
    .waitDuration(Duration.ofMillis(100))
    .build();

Retry retry = Retry.of("backendService", config);

六、分布式事务

6.1 CAP 定理

┌─────────────────────────────────────────────────────────────┐
│                    CAP 定理                                  │
│                                                              │
│  Consistency (一致性)                                        │
│       │                                                     │
│       ├───────────────────┐                                  │
│       │                   │                                  │
│   Availability       Partition                              │
│   (可用性)           Tolerance                              │
│   (分区容错)         (必须满足两个)                         │
└─────────────────────────────────────────────────────────────┘

6.2 TCC 模式

// Try: 预留资源
@Compensable(confirmMethod = "confirmOrder", cancelMethod = "cancelOrder")
public void createOrder(Order order) {
    // 冻结库存
    inventoryService.freezeStock(order.getItems());
    // 冻结余额
    accountService.freezeBalance(order.getUserId(), order.getTotal());
}

// Confirm: 确认执行
public void confirmOrder(Order order) {
    inventoryService.deductStock(order.getItems());
    accountService.deductBalance(order.getUserId(), order.getTotal());
}

// Cancel: 取消回滚
public void cancelOrder(Order order) {
    inventoryService.unfreezeStock(order.getItems());
    accountService.unfreezeBalance(order.getUserId(), order.getTotal());
}

6.3 Saga 模式

# 订单服务 → 支付服务 → 物流服务
# 每个服务有正向操作和补偿操作

order_service:
  create_order:       # 创建订单
    compensate: cancel_order
  
payment_service:
  process_payment:    # 处理支付
    compensate: refund_payment

shipping_service:
  ship_order:         # 发货
    compensate: cancel_ship

七、API 网关

7.1 Kong 配置

# 服务
curl -X POST http://localhost:8001/services \
  -d '{"name":"user-service","url":"http://user-service:8080"}'

# 路由
curl -X POST http://localhost:8001/services/user-service/routes \
  -d '{"paths":["/users"],"methods":["GET","POST"]}'

# 认证插件
curl -X POST http://localhost:8001/services/user-service/plugins \
  -d '{"name":"jwt","config":{"key_claim":"user_id"}}'

7.2 Spring Cloud Gateway

spring:
  cloud:
    gateway:
      routes:
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/users/**
          filters:
            - StripPrefix=1
            - AddRequestHeader=X-Gateway, SpringCloud

八、总结

微服务架构核心要点：

1. 拆分：业务边界
2. 通信：同步/异步
3. 发现：Consul/Eureka
4. 容错：熔断/重试
5. 事务：TCC/Saga
6. 网关：统一入口

掌握这些，微服务架构 so easy！