spring cloud hystrix在普通应用和feign上使用

hystrix普通用法

引入包

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

在main类中添加注解

@EnableCircuitBreaker

@SpringBootApplication
@EnableEurekaClient
@EnableCircuitBreaker
public class MicroserviceSimpleConsumerApplication {

@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}

public static void main(String[] args) {
SpringApplication.run(MicroserviceSimpleConsumerApplication.class, args);

在接口处实现fallback方法使用

@HystrixCommand

注解，指明方法名

@GetMapping("/consumer/{id}")
@HystrixCommand(fallbackMethod = "findByIdFallback", commandProperties = @HystrixProperty(name = "execution.isolation.strategy", value = "SEMAPHORE"))
public User findById(@PathVariable("id") Long id) {
return this.restTemplate.getForObject("http://SIMPLE-PROVIDER/provider/" + id, User.class);
}

public User findByIdFallback(Long id) {
User u = new User();
u.setId(-1L);
return u;
}

hystrix在feign中应用

注意的是：fegin中默认hystrix功能是关闭的，具体见https://github.com/spring-cloud/spring-cloud-netflix/issues/1277

首先开启feign中的hystrix功能

feign:
hystrix:
enabled: true

使用

@FeignClient

注解属性进行设置fallback

@FeignClient(name = "SIMPLE-PROVIDER", fallback = HystrixFallBackClient.class)
public interface UserFeignClient {

@GetMapping("/provider/{id}")
public User findUserById(@PathVariable("id") Long id);
}

写fallback的类

package com.example.demo.client;

import org.springframework.stereotype.Component;

import com.example.demo.entity.User;

@Component
public class HystrixFallBackClient implements UserFeignClient {

@Override
public User findUserById(Long id) {
User user = new User();
user.setId(0L);
return user;
}
}

另外一种写fallback方法

利用fallbackFactory进行编写（原理和直接写fallback类似，但factory可以提供异常信息）

@FeignClient(name = "SIMPLE-PROVIDER", configuration = UserFeignClientConfig.class, /**fallback = UserFeignClientFallback.class,**/ fallbackFactory = UserClientfallbackFactory.class)
public interface UserFeignClient {

@GetMapping("/provider/{id}")
@HystrixCommand(fallbackMethod = "findUserByIdFallback")
public User findUserById(@PathVariable("id") Long id);
}

编写factory类实现client接口

package com.example.demo.client;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import com.example.demo.entity.User;

import feign.hystrix.FallbackFactory;

@Component
public class UserClientfallbackFactory implements FallbackFactory<UserFeignClient> {

Logger log = LoggerFactory.getLogger(UserClientfallbackFactory.class);

@Override
public UserFeignClient create(Throwable cause) {
return new UserFeignClient() {

@Override
public User findUserById(Long id) {
log.info("fall back cause :{}", cause.getMessage());
User u = new User();
u.setId(-2L);
u.setName("fallbackFactory");
return u;
}

};

}

}

注意的是：

@FeignClient

中的fallback和fallbackFactory只能同时配一个

hystrix用法总结

– 使用hystrix自生的注解

– 使用feign注解中的设置