OpenFeign

1.引入依赖

  <!--openFeign-->
  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-openfeign</artifactId>
  </dependency>
  <!--负载均衡器-->
  <dependency>
      <groupId>org.springframework.cloud</groupId>
      <artifactId>spring-cloud-starter-loadbalancer</artifactId>
  </dependency>

---

2.编写OpenFeign客户端

@FeignClient(name="item-service",path = "/items")
public interface ItemClient {
    @GetMapping
    List<ItemDTO> queryItemByIds(@RequestParam("ids") Collection<Long> ids);
}

• @FeignClient(name="item-service") ：声明服务名称
• @FeignClient(path = "/items"): 相当于ItemController类上的@RequestMapping("/items")指定的路径
• @GetMapping ：声明请求方式
• @RequestParam("ids") Collection ids ：声明请求参数
• List ：返回值类型

---

3.使用FeignClient

@Autowired
private ItemClient itemClien;
List<ItemDTO> items = itemClient.queryItemByIds(itemIds);

• @Autowired：依赖注入
• queryItemByIds：调用方法

---

4.启用OpenFeign

@EnableFeignClients
@MapperScan("com.hmall.cart.mapper")
@SpringBootApplication
public class CartApplication {
    public static void main(String[] args) {
        SpringbootApplication.run(CartApplication.class, args);
    } 
}

• @EnableFeignClients：寻找使用@FeignClient 注解的接口生成Feign客户端