Feign独立使用-远程调用

1.引入依赖

Maven坐标

<!--feign 依赖-->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
    <version>${feign.version}</version>
</dependency>

2. 定义FeignClient

/**
 * @description:  基础服务
 *
 * FeignClient注解：
 * name/value属性: 这两个的作用是一样的,指定的是调用服务的微服务名称（独立使用时，只需唯一） 可以使用环境变量或者jvm属性定义url字段
 * url： 定义远程服务的domain
 * fallbackFactory: 定义熔断器（可以在熔断器中定义熔断处理，返回兜底的结果）
 *
 * @date: 2020/11/24 14:49
 * @author: fdh
 */
//@FeignClient(name = "baseSapi", url = "${qs.sapi.base.url.prefix}", fallbackFactory = RemoteBaseFallBackFactory.class)
@FeignClient(name = "baseSapi", url = "http://localhost:9001", fallbackFactory = RemoteBaseFallBackFactory.class)
public interface RemoteBaseService {

    /**
     * 获取考季知识点
     *
     * 接口地址： http:// xxxxx
     *
     * @param seasonId
     * @return
     */
    @RequestMapping(value = "/s1/v1/seasonKnowledgePoint/kpListBySeasonId", method = RequestMethod.GET)
    SapiResult<List<KnowledgePointVo>> getKpListBySeasonId(@RequestParam("seasonId") Long seasonId);
}

 3.定义熔断器

/**
 * @description:  远程基础熔断工厂
 * @date: 2020/11/25 13:48
 * @author: fdh
 */
@Component
public class RemoteBaseFallBackFactory implements FallbackFactory<RemoteBaseService> {

    @Override
    public RemoteBaseService create(Throwable throwable) {
        RemoteBaseFallBackServiceImpl remoteBaseFallBackService = new RemoteBaseFallBackServiceImpl();
        remoteBaseFallBackService.setThrowable(throwable);
        return remoteBaseFallBackService;
    }
}

4.定义FeignClient熔断实现

/**
 * @description:  RemoteBaseService熔断处理
 * @date: 2020/11/25 13:49
 * @author: fdh
 */
public class RemoteBaseFallBackServiceImpl implements RemoteBaseService {

    private static final Logger log = LoggerFactory.getLogger(RemoteBaseFallBackServiceImpl.class);

    @Setter
    private Throwable throwable;

    private void printLog(String modules, Throwable throwable){
        if( modules == null ){
            modules = StringUtils.EMPTY;
        }
        log.info("{}异常:", modules, throwable);
    }

    @Override
    public SapiResult<List<KnowledgePointVo>> getKpListBySeasonId(Long seasonId) {
        printLog("知识点接口", throwable);
        return SapiResultUtil.success(Collections.emptyList());
    }
}

5. 扫描FeignClient

/**
 * @description:  启动类
 * @date: 2020/11/25 13:52
 * @author: fdh
 */
@SpringBootApplication
@EnableFeignClients(basePackages = "com.xxx.feign")
public class DaApplication extends SpringBootServletInitializer {
    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(DaApplication.class);
    }

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

---

以上就可以实现Feign独立使用，不依赖注册中心，进行独立远程调用

补充：

1. 生产环境上往往需要记录FeignClient远程调用日志，我们可以定义日志输出级别

/**
 * @description:  Feign日志
 * @date: 2020/11/5 16:35
 * @author: fdh
 */
@Configuration
public class FeignConfig {
    @Bean
    Logger.Level feignLoggerLevel() {
        return Logger.Level.FULL;
    }
}

推荐日志级别：

级别	打印内容
NONE(默认值)	不记录任何日志
BASIC(更适合生产环境)	仅记录请求方法、URL、响应状态代码以及执行时间
HEADERS	记录BASIC级别的基础上,记录请求和响应的 header
FULL(更适合开发环境)	记录请求和响应的 header、body和元数据

 

 

 

 

 

 

2. 启用熔断并设置熔断超时时间（默认1秒）

feign.hystrix.enabled=true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 30000

---

统一处理，需要增加FeignClient远程调用携带加密参数

@Component
public class FeignRequestInterceptor implements RequestInterceptor {

    private org.slf4j.Logger log = LoggerFactory.getLogger(FeignRequestInterceptor.class);
    
    @Override
    public void apply(RequestTemplate requestTemplate) {
        try {
            // xxxx 算法
            //String sign = DigestUtils.md5DigestAsHex(params.getBytes("utf-8"));
            requestTemplate.query("sign", "xxxxxx");
        } catch (UnsupportedEncodingException e) {
            log.error("签名失败：", e);
        }
    }
    
}