Spring Cloud

概述

Spring Cloud 是基于 Spring Boot 的微服务框架，提供了一整套微服务解决方案。

服务注册与发现

Nacos

# application.yml
spring:
  application:
    name: user-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
        namespace: dev

@SpringBootApplication
@EnableDiscoveryClient
public class UserServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserServiceApplication.class, args);
    }
}

服务调用

// 使用 RestTemplate
@Configuration
public class RestConfig {
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}

@Service
public class OrderService {
    @Autowired
    private RestTemplate restTemplate;
    
    public User getUser(Long userId) {
        return restTemplate.getForObject(
            "http://user-service/users/" + userId, 
            User.class
        );
    }
}

OpenFeign

// 定义 Feign 客户端
@FeignClient(name = "user-service", fallback = UserClientFallback.class)
public interface UserClient {
    
    @GetMapping("/users/{id}")
    User getUser(@PathVariable("id") Long id);
    
    @PostMapping("/users")
    User createUser(@RequestBody User user);
}

// 降级实现
@Component
public class UserClientFallback implements UserClient {
    @Override
    public User getUser(Long id) {
        return new User(-1L, "默认用户");
    }
    
    @Override
    public User createUser(User user) {
        return null;
    }
}

// 使用
@Service
public class OrderService {
    @Autowired
    private UserClient userClient;
    
    public Order createOrder(Long userId) {
        User user = userClient.getUser(userId);
        // ...
    }
}

配置中心

Nacos Config

# bootstrap.yml
spring:
  application:
    name: user-service
  cloud:
    nacos:
      config:
        server-addr: localhost:8848
        file-extension: yaml
        namespace: dev
        group: DEFAULT_GROUP

@RestController
@RefreshScope  // 支持配置热更新
public class ConfigController {
    
    @Value("${app.name}")
    private String appName;
    
    @GetMapping("/config")
    public String getConfig() {
        return appName;
    }
}

API 网关

Spring Cloud Gateway

spring:
  cloud:
    gateway:
      routes:
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/api/users/**
          filters:
            - StripPrefix=1
            - AddRequestHeader=X-Request-Source, gateway
        
        - id: order-service
          uri: lb://order-service
          predicates:
            - Path=/api/orders/**
          filters:
            - StripPrefix=1

自定义过滤器

@Component
public class AuthFilter implements GlobalFilter, Ordered {
    
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        String token = exchange.getRequest().getHeaders().getFirst("Authorization");
        
        if (token == null || !validateToken(token)) {
            exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
            return exchange.getResponse().setComplete();
        }
        
        return chain.filter(exchange);
    }
    
    @Override
    public int getOrder() {
        return -100;
    }
    
    private boolean validateToken(String token) {
        // 验证 token
        return true;
    }
}

限流配置

spring:
  cloud:
    gateway:
      routes:
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/api/users/**
          filters:
            - name: RequestRateLimiter
              args:
                redis-rate-limiter.replenishRate: 10
                redis-rate-limiter.burstCapacity: 20
                key-resolver: "#{@ipKeyResolver}"

@Configuration
public class RateLimiterConfig {
    
    @Bean
    public KeyResolver ipKeyResolver() {
        return exchange -> Mono.just(
            exchange.getRequest().getRemoteAddress().getAddress().getHostAddress()
        );
    }
}

负载均衡

LoadBalancer

@Configuration
public class LoadBalancerConfig {
    
    @Bean
    public ReactorLoadBalancer<ServiceInstance> randomLoadBalancer(
            Environment environment,
            LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
        return new RandomLoadBalancer(
            loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class),
            name
        );
    }
}

链路追踪

Sleuth + Zipkin

spring:
  sleuth:
    sampler:
      probability: 1.0
  zipkin:
    base-url: http://localhost:9411

@Slf4j
@RestController
public class UserController {
    
    @GetMapping("/users/{id}")
    public User getUser(@PathVariable Long id) {
        log.info("Getting user: {}", id);  // 自动包含 traceId
        return userService.getUser(id);
    }
}

完整配置示例

server:
  port: 8080

spring:
  application:
    name: user-service
  cloud:
    nacos:
      discovery:
        server-addr: ${NACOS_SERVER:localhost:8848}
        namespace: ${NACOS_NAMESPACE:dev}
      config:
        server-addr: ${NACOS_SERVER:localhost:8848}
        namespace: ${NACOS_NAMESPACE:dev}
        file-extension: yaml

feign:
  client:
    config:
      default:
        connectTimeout: 5000
        readTimeout: 5000
  circuitbreaker:
    enabled: true

management:
  endpoints:
    web:
      exposure:
        include: "*"
  endpoint:
    health:
      show-details: always