Spring OpenFegin 实现微服务间 RPC 调用

添加依赖

Spring Boot 2.6.7、openfeign 3.1.2

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.6.7</version>
    <relativePath/>
</parent>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
    <version>3.1.2</version>
</dependency>

第三方服务

@RestController
public class HelloController {

    @GetMapping("/hello/{id}")
    public Response helloGetPathVariable(@PathVariable("id") Integer id) throws InterruptedException {
        // Thread.sleep(4000);
        return Response.builder().msg("ok-get-PathVariable-" + id).build();
    }

}

启用 Feign

使用@EnableFeignClients开启FeginClient。

@EnableFeignClients
@SpringBootApplication
public class LearnSpringCloudOpenfeignApplication {

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

}

FeginClient

使用@FeignClient表示改类是一个Fegin客户端。

@FeignClient(name = "my-feign-client", url = "http://localhost:8080")
public interface MyFeignService {

    @GetMapping("/hello/{id}")
    Response helloGetPathVariable(@PathVariable("id") Integer id);
}

RequestInterceptor

添加请求拦截器，需在application.yml中配置

@Slf4j
public class TokenRequestInterceptor implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate requestTemplate) {
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        String token = request.getHeader("token");
        log.info("token request interceptor#{}, token#{}", requestTemplate, token);
    }
}

Fegin 配置文件

• compression：开启请求和响应的压缩
• default：默认Fegin客户端配置
• loggerLevel：日志等级（需配合logging.level）
• logging.level：需同时开启feign的loggerLevel
• requestInterceptors：请求拦截器，责任链

feign:
  compression:
    request:
      enabled: true
      mime-types: text/xml,application/xml,application/json
      min-request-size: 2048
    response:
      enabled: true
  client:
    config:
      default:
        connect-timeout: 5000
        read-timeout: 3000
        loggerLevel: full
        requestInterceptors:
          - com.example.learnspringcloudopenfeign.feign.interceptor.TokenRequestInterceptor
          - com.example.learnspringcloudopenfeign.feign.interceptor.TestRequestInterceptor
logging:
  level:
    com.example.learnspringcloudopenfeign: debug

可能出现的错误

Description:

Your project setup is incompatible with our requirements due to following reasons:

- Spring Boot [2.6.7] is not compatible with this Spring Cloud release train


Action:

Consider applying the following actions:

- Change Spring Boot version to one of the following versions [2.4.x, 2.5.x] .
You can find the latest Spring Boot versions here [https://spring.io/projects/spring-boot#learn]. 
If you want to learn more about the Spring Cloud Release train compatibility, you can visit this page [https://spring.io/projects/spring-cloud#overview] and check the [Release Trains] section.
If you want to disable this check, just set the property [spring.cloud.compatibility-verifier.enabled=false]

原因

解决办法

方法一

升级openfeign版本。

方法二

禁用兼容性校验。

spring.cloud.compatibility-verifier.enabled=false

openfeign 版本信息

https://spring.io/projects/spring-cloud-openfeign#learn

帮助文档

https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html