Feign整合Sentinel实现熔断降级处理

Sentinel可以整合Feign进行熔断处理。特别是Hystrix宣布不再维护后，可以轻松的切换成这种方案。整合过程与Hystrix类似

加入alibaba-Sentinel依赖

<dependency>
  <groupId>com.alibaba.cloud</groupId>
  <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

yml文件配置启用 Feign 整合 Sentinel 的自动配置

# 开启feign对sentinel的支持
feign:
  sentinel:
    enabled: true

Feign接口

@FeignClient(value="user", configuration = FeignExceptionConfig.class, fallbackFactory = UserFeignClientFallbackFactory.class, decode404 = true)
public interface UserFeignClient {

    /**
     * feign rpc访问远程/users/login接口
     * @param username
     * @return
     */
    @GetMapping(value = "/users/login", params = "username")
    LoginAppUser findByUsername(@RequestParam("username") String username);

    @GetMapping(value = "/users/mobile", params = "mobile")
    LoginAppUser findByMobile(@RequestParam("mobile") String mobile);

    @GetMapping(value = "/users", params = "params")
    PageResult<SysUser> findUsers(@RequestParam Map<String, Object> params);
}

降级处理类

使用FallbackFactory的方式

import feign.hystrix.FallbackFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.util.Map;

@Component
public class UserFeignClientFallbackFactory implements FallbackFactory<UserFeignClient> {

    private static final Logger log = LoggerFactory.getLogger(UserFeignClientFallbackFactory.class);

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

            @Override
            public LoginAppUser findByUsername(String username) {
                log.error("通过用户名查询用户异常:{}", username, throwable);
                return new LoginAppUser() ;
            }

            @Override
            public LoginAppUser findByMobile(String mobile) {
                log.error("通过手机号查询用户异常:{}", mobile, throwable);
                return new LoginAppUser();
            }

            @Override
            public PageResult<SysUser> findUsers(Map<String, Object> params) {
                log.error("查询用户列表异常:{}");
                return null;
            }

        };
    }
}