前言
Feign组件默认使用Ribbon的重试机制并增加了根据状态码判断重试机制，默认情况下是不启用的。Feign使用的是Spring Retry组件，需要引入依赖才能启用。
一、POM引入Spring Retry
<dependency><groupId>org.springframework.retry</groupId><artifactId>spring-retry</artifactId></dependency>
二、配置文件
eureka-client:ribbon:MaxAutoRetries: 1MaxAutoRetriesNextServer: 1retryableStatusCodes: 500,404 OkToRetryOnAllOperations: true NFLoadBalancerRuleClassName: com.netflix.loadbalancer.AvailabilityFilteringRule #负载均衡规则
eureka-client是自己的serverId，MaxAutoRetries同一台服务器上的最大重试次数（不包括第一次尝试），MaxAutoRetriesNextServer要重试的下一个服务器的最大数量（不包括第一个服务器），retryableStatusCodes可以根据接口返回的状态码判断是否重试其他服务，OkToRetryOnAllOperations只对所有的超时请求重试
注意： Ribbon的重试机制只有对GET请求或者设置了OkToRetryOnAllOperations生效 详情请查看源码：
public class RibbonLoadBalancedRetryPolicy implements LoadBalancedRetryPolicy {...public Boolean canRetry(LoadBalancedRetryContext context) {HttpMethod method = context.getRequest().getMethod();return HttpMethod.GET == method || lbContext.isOkToRetryOnAllOperations();}... }
Feign对返回状态码做了重试判断RetryableFeignLoadBalancer
public class RetryableFeignLoadBalancer extends FeignLoadBalancerimplements ServiceInstanceChooser {...[@Override](https://my.oschina.net/u/1162528)public RibbonResponse execute(final RibbonRequest request,IClientConfig configOverride) throws IOException {...if (retryPolicy != null&& retryPolicy.retryableStatusCode(response.status())) {byte[] byteArray = response.body() == null ? new byte[] {}: StreamUtils.copyToByteArray(response.body().asInputStream());response.close();throw new RibbonResponseStatusCodeException(RetryableFeignLoadBalancer.this.clientName, response,byteArray, request.getUri());}...}... }
重试机制用的是Spring Retry组件当抛出异常时进行重试！
GET请求指的是feign client 请求其他client时声明的那个interface中mapping注解类型，RequestMapping不设置method默认为GET请求
@FeignClient("stores")
public interface StoreClient {@RequestMapping(method = RequestMethod.GET, value = "/stores")List<Store> getStores();@RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")Store update(@PathVariable("storeId") long storeId, Store store);
}
写在最后
