转:SpringBoot+SpringCloud —— 使用Feign消费服务
Feign简介
Spring Cloud Feign是基于Netflix Feign实现,整合了Spring Cloud Riggon与Spring Cloud Hystrix,出了提供这两者的强大功能外,他还提供了一种声明式的Web服务客户端定义方式。
在使用Spring Cloud Ribbon时,通常都会利用它对RestTemplate的请求拦截来实现对服务的调用,而RestTemplate已经实现了对HTTP请求的封装处理,形成了一套模板化的调用方法。
快速使用
添加对feign的依赖:
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-feign</artifactId> </dependency>
在主类使用注解开启Feign的功能:
@SpringBootApplication @EnableDiscoveryClient @EnableFeignClients public class OwlBookstoreWebApiApplication { public static void main(String[] args) { SpringApplication.run(OwlBookstoreWebApiApplication.class, args); } }
接着,创建调用接口,使用注解来消费服务:
import org.springframework.cloud.netflix.feign.FeignClient; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import cn.net.bysoft.owl.bookstore.facade.user.entity.User; import cn.net.bysoft.owl.bookstore.web.api.fallback.UserServiceFallbackFactory; @FeignClient(value = "https://my.oschina.net/u/2450666/blog/SERVICE-USER", fallbackFactory = UserServiceFallbackFactory.class) public interface UserService { @RequestMapping(value = "https://my.oschina.net/users/{email}/", method = RequestMethod.GET) Boolean isExistsByEmail(@PathVariable("email") String email); @RequestMapping(value = "https://my.oschina.net/users/{id}", method = RequestMethod.GET) User findById(@PathVariable("id") Long id); }
接口中声明的方法的参数与返回值,要与服务提供的方法一致。
Feign自动开启了Ribbon中的负载均衡和hystrix断路器,要使用断路器先需要开启断路器:
feign: hystrix: enabled: true compression: request: enabled: true response: enabled: true
我在Feign中使用的是fallbackFactory来降级服务,使用该方式可以同时处理服务抛出的异常,创建一个UserServiceFallbackFactory类:
import org.springframework.stereotype.Component; import cn.net.bysoft.owl.bookstore.facade.user.entity.User; import cn.net.bysoft.owl.bookstore.web.api.service.UserService; import feign.hystrix.FallbackFactory; @Component public class UserServiceFallbackFactory implements FallbackFactory<UserService> { @Override public UserService create(Throwable cause) { return new UserService() { @Override public Boolean isExistsByEmail(String email) { system.out.println(cause.getmessage()); return false; } @Override public User findById(Long id) { cause.printStackTrace(); System.out.println(cause.getMessage()); return null; } }; } }
Feign配置
Ribbon配置
全局配置的方法很简单:
ribbon.ConnectTimeout=500 ribbon.ReadTimeout=5000