Spring Cloud Alibaba 的学习之feign篇

是什么？

Feign 是一个声明式的伪 HTTP 客户端，它使得写 HTTP 客户端变得更简单

为什么？

使用 Feign，只需要创建一个接口并注解。它具有可插拔的注解特性。Feign 支持可插拔的编码器和解码器。Feign 默认集成了 Ribbon，Nacos 也很好的兼容了 Feign，默认实现了负载均衡的效果

怎么做

提供者：

yml:

spring:
  application:
    name: puzzle-provider

  cloud:
    nacos:
      discovery:
        server-addr: 192.168.233.150:8848

server:
  port: 11000

management:
  endpoints:
    web:

application:

@SpringBootApplication
@EnableDiscoveryClient
public class PuzzleProviderApplication {
    public static void main(String[] args) {
        SpringApplication.run(PuzzleProviderApplication.class, args);
    }
}

service:

@Service
public class InitPuzzleServiceImpl implements InitPuzzleService {
    @Override
    public List initPuzzle() {
        List list= Arrays.asList("1", "2", "3","4","5","6","7","8","0");
        return list;
    }
}

controller

@RestController
public class InitPuzzleController {

    @Autowired
    private InitPuzzleService initPuzzleService;

    @GetMapping(value = "init")
    public List initPuzzle() {
        return initPuzzleService.initPuzzle();
    }
}

消费者：

yml:

spring:
  application:
    name: consumer-reset

  cloud:
    nacos:
      discovery:
        server-addr: 192.168.233.150:8848
feign:
  sentinel:
    enabled: true
server:
  port: 12000

management:
  endpoints:
    web:
      exposure:
        include: "*"

POM

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

Application(主要添加EnableFeignClients)

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class PuzzleResetApplication {
    public static void main(String[] args) {
        SpringApplication.run(PuzzleResetApplication.class, args);
    }
}

Service（@FeignClient("服务名") 注解来指定调用哪个服务）

@FeignClient(value = "puzzle-provider")
public interface ResetService {
    @GetMapping(value = "init")
    List initPuzzle();
}

Controller

@RestController
public class ResetController {

    @Autowired
    private ResetService resetService;

    @GetMapping("/reset")
    public List resetPuzzle(){
        List list = resetService.initPuzzle();
        Collections.shuffle(list);
        return list;
    }
}

配置负载均衡

修改 service-provider 服务的端口号如 11000，并启动多个实例，IDEA 中依次点击 Run -> Edit Configurations 并勾选 Allow parallel run 以允许 IDEA 多实例运行项目