Feign默认已经整合了Hystrix，本节详细探讨Feign使用Hystrix的具体细节。
服务降级
1 加配置，默认Feign是不启用Hystrix的，需要添加如下配置启用Hystrix，这样所有的Feign Client都会受到Hystrix保护！
feign:
hystrix:
enabled: true
2 提供Fallback：
@FeignClient(name = "microservice-provider-user", fallback = UserFeignClientFallback.class)
public interface UserFeignClient {
@GetMapping("/users/{id}")
User findById(@PathVariable("id") Long id);
}
@Component
class UserFeignClientFallback implements UserFeignClient {
@Override
public User findById(Long id) {
return new User(id, "默认用户", "默认用户", 0, new BigDecimal(1));
}
}
获得造成fallback的原因
@FeignClient(name = "microservice-provider-user", fallbackFactory = UserFeignClientFallbackFactory.class)
public interface UserFeignClient {
@GetMapping("/users/{id}")
User findById(@PathVariable("id") Long id);
}
@Component
@Slf4j
class UserFeignClientFallbackFactory implements FallbackFactory<UserFeignClient> {
@Override
public UserFeignClient create(Throwable throwable) {
return new UserFeignClient() {
@Override
public User findById(Long id) {
log.error("进入回退逻辑", throwable);
return new User(id, "默认用户", "默认用户", 0, new BigDecimal(1));
}
};
}
}
Feign启用/禁用Hystrix
全局启用
feign.hystrix.enabled: true
全局禁用
feign.hystrix.enabled: false
或直接省略不写。
局部启用
利用Feign配置的自定义，为指定Feign Client指定如下配置类即可，Feign配置自定义详见：跟我学Spring Cloud(Finchley版)-10-Feign深入
public class FeignDisableHystrixConfiguration {
@Bean
@Scope("prototype")
public HystrixFeign.Builder feignBuilder() {
return HystrixFeign.builder();
}
}
局部禁用
public class FeignDisableHystrixConfiguration {
@Bean
@Scope("prototype")
public Feign.Builder feignBuilder() {
return Feign.builder();
}
}
配套代码
服务降级：
1 GitHub：https://github.com/eacdy/spring-cloud-study/tree/master/2018-Finchley/microservice-consumer-movie-feign-hystrix
2 Gitee：https://gitee.com/itmuch/spring-cloud-study/tree/master/2018-Finchley/microservice-consumer-movie-feign-hystrix
获得造成fallback的原因：
1 GitHub：https://github.com/eacdy/spring-cloud-study/tree/master/2018-Finchley/microservice-consumer-movie-feign-hystrix-fallback-factory
2 Gitee：https://gitee.com/itmuch/spring-cloud-study/tree/master/2018-Finchley/microservice-consumer-movie-feign-hystrix-fallback-factory
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