声明式服务调用Feign

Feign概述：

Feign是Spring Cloud提供的声明式、模板化的HTTP客户端，它使得调用远程服务就像调用本地服务一样简单，只需要创建一个接口并添加一个注解即可。

Spring Cloud集成Fegin并对其进行了增强，使Fegin支持了Spring MVC注解；Fegin默认集成了Ribbon，所以Fegin默认就实现了负载均衡的效果。

Fegin入门：

创建工程：

• 拷贝ribbon_provider_1（上一章ribbon）

• 

 配置文件：application.yml

server:
  port: 9090
spring:
  cloud:
    nacos:
      discovery:
        server-addr: 192.168.203.131:8848
  application:
    name: feign-provider

创建feign接口：

pom.xml：

            org.springframework.cloud
            spring-cloud-starter-openfeign
        
        
            com.bjpowernode
            springcloud_common
            1.0-SNAPSHOT
        

feign接口：

@FeignClient(value="sentinel-provider",fallbackFactory = UserFeignFallback.class)
@RequestMapping(value = "/provider")
public interface UserFeign {
    @RequestMapping(value = "/getUserById/{id}")
    public User getUserById(@PathVariable(value="id") Integer id);
}

创建服务消费者：

• 拷贝ribbon_consumer

 

pom.xml：

            org.springframework.boot
            spring-boot-starter-web
        
        
            com.bjpowernode
            springcloud_common
            1.0-SNAPSHOT
        
        
            com.alibaba.cloud
            spring-cloud-starter-alibaba-nacos-discovery
        
        
        
            com.bjpowernode
            feign_interface
            1.0-SNAPSHOT
        

配置文件：application.yml

server:
  port: 80
spring:
  cloud:
    nacos:
      discovery:
        server-addr: 192.168.203.131:8848
  application:
    name: feign-consumer

controller:

@RestController
@RequestMapping(value = "/consumer")
public class ConsumerController {

    @Autowired
    private UserFeign userFeign;

    @RequestMapping(value = "/getUserById/{id}")
    public User getUserById(@PathVariable Integer id) {
        return userFeign.getUserById(id);
    }
}

app:

@SpringBootApplication
@EnableDiscoveryClient
//@EnableFeignClients(basePackages = "com.bjpowernode.feign")
@EnableFeignClients//开启feign接口扫描
public class ConsumerApp {

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

测试：略.