Spring Cloud为开发人员提供了快速构建分布式系统的工具，本文将详细介绍Spring Cloud的核心组件和最佳实践。
服务注册与发现
Eureka Server配置
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@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(EurekaServerApplication.class, args);
}
}
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# application.yml
server:
port: 8761
eureka:
client:
registerWithEureka: false
fetchRegistry: false
server:
waitTimeInMsWhenSyncEmpty: 0
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Eureka Client配置
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@SpringBootApplication
@EnableDiscoveryClient
public class ServiceApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceApplication.class, args);
}
}
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spring:
application:
name: user-service
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
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服务调用
Feign声明式调用
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@FeignClient(name = "user-service")
public interface UserClient {
@GetMapping("/users/{id}")
User getUser(@PathVariable("id") Long id);
@PostMapping("/users")
User createUser(@RequestBody User user);
}
@RestController
public class OrderController {
@Autowired
private UserClient userClient;
@GetMapping("/orders/{orderId}/user")
public User getUserByOrderId(@PathVariable Long orderId) {
Order order = orderService.getOrder(orderId);
return userClient.getUser(order.getUserId());
}
}
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负载均衡
Ribbon配置
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@Configuration
public class RibbonConfig {
@Bean
public IRule ribbonRule() {
return new WeightedResponseTimeRule();
}
}
@RibbonClient(name = "user-service", configuration = RibbonConfig.class)
public class ServiceConfiguration {
}
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服务熔断
Hystrix配置
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@EnableCircuitBreaker
@SpringBootApplication
public class ServiceApplication {
public static void main(String[] args) {
SpringApplication.run(ServiceApplication.class, args);
}
}
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@Service
public class UserService {
@HystrixCommand(fallbackMethod = "getUserFallback",
commandProperties = {
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "1000"),
@HystrixProperty(name = "circuitBreaker.requestVolumeThreshold", value = "20"),
@HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "50"),
@HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "5000")
})
public User getUser(Long id) {
return userClient.getUser(id);
}
public User getUserFallback(Long id) {
return new User("默认用户");
}
}
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配置中心
Config Server
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@EnableConfigServer
@SpringBootApplication
public class ConfigServerApplication {
public static void main(String[] args) {
SpringApplication.run(ConfigServerApplication.class, args);
}
}
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spring:
cloud:
config:
server:
git:
uri: https://github.com/config-repo
searchPaths: '{application}'
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Config Client
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spring:
cloud:
config:
uri: http://localhost:8888
label: master
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@RefreshScope
@RestController
public class ConfigController {
@Value("${custom.property}")
private String customProperty;
@GetMapping("/property")
public String getProperty() {
return customProperty;
}
}
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服务网关
Spring Cloud Gateway
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@EnableDiscoveryClient
@SpringBootApplication
public class GatewayApplication {
public static void main(String[] args) {
SpringApplication.run(GatewayApplication.class, args);
}
}
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spring:
cloud:
gateway:
routes:
- id: user_service
uri: lb://user-service
predicates:
- Path=/users/**
filters:
- StripPrefix=1
- name: CircuitBreaker
args:
name: userCircuitBreaker
fallbackUri: forward:/fallback
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分布式链路追踪
Sleuth + Zipkin
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<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-sleuth</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zipkin</artifactId>
</dependency>
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spring:
zipkin:
base-url: http://localhost:9411
sleuth:
sampler:
probability: 1.0
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消息总线
Spring Cloud Bus
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@RefreshScope
@RestController
public class ConfigController {
@Autowired
private BusProperties busProperties;
@PostMapping("/actuator/bus-refresh")
public void refresh() {
// 刷新配置
}
}
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安全配置
OAuth2集成
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@EnableResourceServer
@SpringBootApplication
public class ResourceServerApplication {
@Bean
public ResourceServerConfigurer resourceServerConfigurer() {
return new ResourceServerConfigurerAdapter() {
@Override
public void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
.antMatchers("/public/**").permitAll()
.anyRequest().authenticated();
}
};
}
}
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监控管理
Spring Boot Admin
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@EnableAdminServer
@SpringBootApplication
public class AdminApplication {
public static void main(String[] args) {
SpringApplication.run(AdminApplication.class, args);
}
}
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spring:
boot:
admin:
client:
url: http://localhost:8080
management:
endpoints:
web:
exposure:
include: "*"
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最佳实践
-
服务拆分原则
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配置管理
-
高可用设计
性能优化
- 服务调用优化
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@Configuration
public class FeignConfig {
@Bean
public Retryer feignRetryer() {
return new Retryer.Default(100, 1000, 4);
}
}
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- 缓存优化
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@Cacheable(value = "users", key = "#id")
public User getUser(Long id) {
return userClient.getUser(id);
}
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总结
Spring Cloud提供了构建微服务架构的完整解决方案，通过合理使用其组件可以快速构建可靠的分布式系统。
参考资料
- Spring Cloud官方文档
- Spring Cloud微服务实战
- Spring Cloud Alibaba实战指南