努力让 SpringCloud Feign 与外部服务一起工作

Question

使用 Feign 访问我在 Eureka 上注册的服务是轻而易举的事。我正在尝试使用 Feign 访问外部服务并在基础知识方面苦苦挣扎。

我正在使用 Bluemix 上的一项服务，但是为了简化手头的问题，我正在使用一项简单的服务。

我的代理显示如下：

//@FeignClient(name = "country-service-client", url = "https://country.io")
@FeignClient(name = "another-country-service-client", url = "http://restcountries.eu/rest/v2/name/Australia")

public interface SimpleServiceProxy {

    //This one works
    @RequestMapping(method = RequestMethod.GET, value = "/names.json", produces = "application/json")
    String getCountries();

    //This one does not work... This is used in conjunction where the url in the Fiegn Client annotation reads as - http://restcountries.eu/rest/v2
    @RequestMapping(method = RequestMethod.GET, value = "/name/{country}", produces = "application/json")
    public String getCountryInfo(@PathVariable("country") String country);



     //This one doesn't work either
    //@RequestMapping(method = RequestMethod.GET, value = "/name/Australia", produces = "application/json")
    public String getCountryInfoHardcodedWithinMethod();
}

    //This works however I would want to pass parameters and path variables to the URL
    @RequestMapping(method = RequestMethod.GET, produces = "application/json")
    public String getCountryInfoHardcodedAtFeignClientAnnotation();
}

我已经尝试了一些变体（参见上面的代码），最后一个在 Feign Client 注释中硬编码 URL 的变体有效。其他人抛出 TimeoutException。

java.util.concurrent.TimeoutException: null
    at com.netflix.hystrix.AbstractCommand.handleTimeoutViaFallback(AbstractCommand.java:958) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.AbstractCommand.access$400(AbstractCommand.java:59) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.AbstractCommand$11.call(AbstractCommand.java:573) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.AbstractCommand$11.call(AbstractCommand.java:565) ~[hystrix-core-1.5.3.jar:1.5.3]
    at rx.internal.operators.OperatorOnErrorResumeNextViaFunction$4.onError(OperatorOnErrorResumeNextViaFunction.java:139) ~[rxjava-1.1.5.jar:1.1.5]
    at rx.internal.operators.OperatorDoOnEach$1.onError(OperatorDoOnEach.java:71) ~[rxjava-1.1.5.jar:1.1.5]
    at rx.internal.operators.OperatorDoOnEach$1.onError(OperatorDoOnEach.java:71) ~[rxjava-1.1.5.jar:1.1.5]
    at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$1.run(AbstractCommand.java:1099) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:41) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable$1.call(HystrixContextRunnable.java:37) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.strategy.concurrency.HystrixContextRunnable.run(HystrixContextRunnable.java:57) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.AbstractCommand$HystrixObservableTimeoutOperator$2.tick(AbstractCommand.java:1116) ~[hystrix-core-1.5.3.jar:1.5.3]
    at com.netflix.hystrix.util.HystrixTimer$1.run(HystrixTimer.java:99) ~[hystrix-core-1.5.3.jar:1.5.3]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[na:1.8.0_112]
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) ~[na:1.8.0_112]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) ~[na:1.8.0_112]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) ~[na:1.8.0_112]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) ~[na:1.8.0_112]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) ~[na:1.8.0_112]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_112]

我很困惑，想弄清楚。在尝试找出 PathVariables 不起作用的原因之前，我想让硬编码的方法起作用。

我错过了什么？ （或者这里做错了）？

Answer 1

我刚刚尝试了这个简单的应用程序，它对我来说很好用 Dalston.RC1

@SpringBootApplication
@EnableFeignClients
@RestController
public class DemoApplication {

    @Autowired
    SimpleServiceProxy proxy;

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

    @RequestMapping("/")
    public String getCountry() {
        return proxy.getCountryInfo("Australia");
    }
}

@FeignClient(name = "another-country-service-client", url ="http://restcountries.eu/rest/v2")
interface SimpleServiceProxy {
    @RequestMapping(method = RequestMethod.GET, value = "/name/{country}", produces = "application/json")
    public String getCountryInfo(@PathVariable("country") String country);
}

您问题中的异常是在发出请求时通过 Hystrix 指示超时。您可以尝试禁用 Hystrix 并使用 feign.hystrix.enabled=false 查看它是否会消失。