第5.1.3 SpringCloud Feign初步

心已赠人 2022-05-12 12:50 149阅读 0赞

dubbo是基于rpc的，实现系统调用，客户端只需要加载接口就可以，服务端负责具体实践。系统与系统之间的调用，就像自己调用自己一样，这样就非常方便了。而通过Rest API，则需要发送http请求，然后解析响应结果，这样通用的一个流程，spring又如何会放过呢，  
[33.服务之间的调用之RPC、Restful深入理解][33._RPC_Restful]，RPC的性能显然比Rest要高，而且开发也较为简单。于是[springcloud 之 Feign Rpc][springcloud _ Feign Rpc]就此诞生了。  
问题是Feign并不是真的RPC，而是伪的，让你在编写代码的时候，看起来像是真的一样方便。  
**1 pom.xml**

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

**2 添加@EnableFeignClients**  
这个是添加在客户端的调用中

@SpringBootApplication
    @ComponentScan(basePackages = {"com.dzmsoft"})
    @MapperScan(basePackages = { "com.dzmsoft.userserver.base.dao" })
    @EnableEurekaClient
    @EnableFeignClients
    @Slf4j
    @EnableAutoConfiguration
    public class UserServerApplication {
        public static void main(String[] args) {
            try {
                SpringApplication.run(UserServerApplication.class, args);
            }finally {
                log.info("server start finish");
            }
        }
    }

**3 客户端调用**  
`gateway-auth`是要提供api服务端的`spring.application.name`, 请求路径`jwt/verify`就是服务端提供的restapi。

import org.springframework.cloud.openfeign.FeignClient;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    
    @FeignClient(value = "gateway-auth")
    public interface ServiceAuthFeign {
    
        @GetMapping("jwt/verify")
        String getInfo(@RequestParam(value = "token") String token);
    
    }

**4 服务端的代码**  
服务端的代码并没有什么特别，就是不同的controller而已

@GetMapping("verify")
        public ResponseEntity<String> verify(@RequestParam(value = "token") String token) throws Exception{
            try {
                if(stringRedisTemplate.opsForValue().get(token)!=null){
                    throw new UserTokenException("token失效，请重新登录");
                }
                IJWTInfo info = authService.validate(token);
                return ResponseEntity.ok(info.getId());
            } catch (ExpiredJwtException ex){
                throw new UserTokenException("User token expired!");
            }catch (SignatureException ex){
                throw new UserTokenException("User token signature error!");
            }catch (IllegalArgumentException ex){
                throw new UserTokenException("User token is null or empty!");
            }
        }

使用起来，就像上面那么简单。  
杨恩雄的《疯狂Spring Cloud微服务架构实战》介绍Feign时，介绍了多种调用REST服务的方式，第一是CXF，CXF是一个webservice框架，那么webservice与REST有什么关系呢？  
先了解一下webservice的发展历史，[SOAP和WebService的那些事][SOAP_WebService]，现有了SOAP，这个协议是厂商之间协定的一个标准，再看看HTTP协议是由[互联网工程工作小组][Link 1]制定的，所以可以想象SOAP的确夹杂着厂商的技术壁垒，而HTTP则不然。于是就发展出来了支持REST的webservice。  
**5 feign超时问题**  
使用feign过程中，最郁闷的是timeout问题，设置各种配置均没能解决.

2021-07-27 18:05:18.352 ERROR c.w.gateway.common.handler.GlobalExceptionHandler - OpenapiServiceFeign#validate(String) timed-out and fallback failed. com.netflix.hystrix.exception.HystrixRuntimeException: OpenapiServiceFeign#validate(String) timed-out and fallback failed.
    	at com.netflix.hystrix.AbstractCommand$22.call(AbstractCommand.java:832)
    	at com.netflix.hystrix.AbstractCommand$22.call(AbstractCommand.java:807)
    	at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140)
    	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    	at com.netflix.hystrix.AbstractCommand$DeprecatedOnFallbackHookApplication$1.onError(AbstractCommand.java:1472)
    	at com.netflix.hystrix.AbstractCommand$FallbackHookApplication$1.onError(AbstractCommand.java:1397)
    	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    	at rx.observers.Subscribers$5.onError(Subscribers.java:230)
    	at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:44)
    	at rx.internal.operators.OnSubscribeThrow.call(OnSubscribeThrow.java:28)
    	at rx.Observable.unsafeSubscribe(Observable.java:10327)
    	at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:51)
    	at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:35)
    	at rx.Observable.unsafeSubscribe(Observable.java:10327)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    	at rx.Observable.unsafeSubscribe(Observable.java:10327)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    	at rx.Observable.unsafeSubscribe(Observable.java:10327)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    	at rx.Observable.unsafeSubscribe(Observable.java:10327)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:41)
    	at rx.internal.operators.OnSubscribeDoOnEach.call(OnSubscribeDoOnEach.java:30)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:48)
    	at rx.internal.operators.OnSubscribeLift.call(OnSubscribeLift.java:30)
    	at rx.Observable.unsafeSubscribe(Observable.java:10327)
    	at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:142)
    	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onError(OnSubscribeDoOnEach.java:87)
    	at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1142)
    	at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41)
    	at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37)
    	at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57)
    	at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1159)
    	at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99)
    	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    	at java.util.concurrent.FutureTask.runAndReset$$$capture(FutureTask.java:308)
    	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java)
    	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
    	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
    	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    	at java.lang.Thread.run(Thread.java:745)
    Caused by: java.util.concurrent.TimeoutException: null
    	at com.netflix.hystrix.AbstractCommand.handleTimeoutViaFallback(AbstractCommand.java:997)
    	at com.netflix.hystrix.AbstractCommand.access$500(AbstractCommand.java:60)
    	at com.netflix.hystrix.AbstractCommand$12.call(AbstractCommand.java:609)
    	at com.netflix.hystrix.AbstractCommand$12.call(AbstractCommand.java:601)
    	at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:140)
    	... 16 common frames omitted
    2021-07-27 18:07:08.418 INFO  c.n.d.shared.resolver.aws.ConfigClusterResolver - Resolving eureka endpoints via configuration
    2021-07-27 18:12:08.419 INFO  c.n.d.shared.resolver.aws.ConfigClusterResolver - Resolving eureka endpoints via configuration

**5.1 设置超时时间**  
[【问题排查】开启 SpringFeign 的 Hystrix 熔断器出现 timed-out and no fallback available 错误][SpringFeign _ Hystrix _ timed-out and no fallback available]  
不需要熔断服务，关闭掉Hystrix

feign:
      hystrix:
        enabled: false

但开放平台是需要开启Hystrix ，在客户端的yml中配置,就调通了，这里没有使用ribbon与hystrix混搭的方式

hystrix:
      command:
        default:
          execution:
            isolation:
              thread:
                timeoutInMilliseconds: 5000  #熔断超时时间

接下来

Caused by: feign.RetryableException: connect timed out executing POST http://openapi-server/feignapi/validate?phoneNumber=17612737265
    	at feign.FeignException.errorExecuting(FeignException.java:213)
    	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:115)
    	at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:80)
    	at feign.hystrix.HystrixInvocationHandler$1.run(HystrixInvocationHandler.java:109)
    	at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:302)
    	at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:298)
    	at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46)
    	... 27 common frames omitted
    Caused by: java.net.SocketTimeoutException: connect timed out

这里增加下面client的超时配置

feign:
      hystrix:
        enabled: true
      client:
        config:
          default:
            connectTimeout: 10000
            readTimeout: 10000

[33._RPC_Restful]: https://blog.csdn.net/u014590757/article/details/80233901
[springcloud _ Feign Rpc]: https://blog.csdn.net/zwx19921215/article/details/79804379
[SOAP_WebService]: https://blog.csdn.net/cxboyee/article/details/77802849
[Link 1]: https://baike.baidu.com/item/%E4%BA%92%E8%81%94%E7%BD%91%E5%B7%A5%E7%A8%8B%E5%B7%A5%E4%BD%9C%E5%B0%8F%E7%BB%84/6992977
[SpringFeign _ Hystrix _ timed-out and no fallback available]: https://ld246.com/article/1545273697839