springcloud-hystrix的使用

使用RestTemplate 请求微服务的时候,需要导入:

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-hystrix</artifactId>
</dependency>

Controller实现如下:

@RestController
public class UserController {
    private static final Logger LOGGER = LoggerFactory.getLogger(UserController.class);

    @Autowired
    private UserFeignService userFeignService;
    @Autowired
    private LoadBalancerClient loadBalancerClient;
    @Autowired
    private RestTemplate restTemplate;

    @HystrixCommand(fallbackMethod = "findByIdFallback")
    @GetMapping("/user/{id}")
    public User findById(@PathVariable Long id) {
        return restTemplate.getForObject("http://spring-user-provider-eureka/" + id, User.class);
    }

    
    public User findByIdFallback(Long id) {
        User user = new User();
        user.setId(-1L);
        user.setName("默认用户");
        return user;
    }
}

其中当restTemplate.getForObject请求微服务失败的时候,调用findByIdFallback方法,返回默认值; 注解@HystrixCommand的fallbackMethod属性的值是方法名, 说明远程失败的时候调用的方法;

注意: 在使用RestTemplate的时候,需要在启动类加上注解@EnableHystrix

使用feign的时候,导入如下依赖:

<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-feign</artifactId>
</dependency>

因为feign已经整合了hystrix,所以不用再导入hystrix的依赖,但是需要在appliation.yml配置文件中加入以下配置:

feign:
  hystrix:
    enabled: true

实现类如下:

@FeignClient(name = "spring-user-provider-eureka", fallback = UserFeignServiceFallback.class)
public interface UserFeignService {

    @RequestMapping(value = "/{id}", method = RequestMethod.GET)
    User findById(@PathVariable("id") Long id);
}

fallback属性指定调用失败的时候,调用的类,这里是UserFeignServiceFallback类,实现了UserFeignSerivce接口

@Component
public class UserFeignServiceFallback implements UserFeignService {
    @Override
    public User findById(@PathVariable("id") Long id) {
        User user = new User();
        user.setId(-2L);
        user.setName("Feign默认用户");
        return user;
    }
}

(小白日记)么么哒

springcloud-hystrix的使用

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