Caused by: java.lang.IllegalStateException: PathVariable annotation was empty on param 1. at feign.Util.checkState(Util.java:128) ~[feign-core-9.5.0.jar:na] at org.springframework.cloud.netflix.feign.annotation.PathVariableParameterProcessor.processArgument(PathVariableParameterProcessor.java:51) ~[spring-cloud-netflix-core-1.4.4.RELEASE.jar:1.4.4.RELEASE] at org.springframework.cloud.netflix.feign.support.SpringMvcContract.processAnnotationsOnParameter(SpringMvcContract.java:238) ~[spring-cloud-netflix-core-1.4.4.RELEASE.jar:1.4.4.RELEASE] at feign.Contract$BaseContract.parseAndValidateMetadata(Contract.java:107) ~[feign-core-9.5.0.jar:na] at org.springframework.cloud.netflix.feign.support.SpringMvcContract.parseAndValidateMetadata(SpringMvcContract.java:133) ~[spring-cloud-netflix-core-1.4.4.RELEASE.jar:1.4.4.RELEASE] at feign.Contract$BaseContract.parseAndValidatateMetadata(Contract.java:64) ~[feign-core-9.5.0.jar:na] at feign.ReflectiveFeign$ParseHandlersByName.apply(ReflectiveFeign.java:146) ~[feign-core-9.5.0.jar:na] at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:53) ~[feign-core-9.5.0.jar:na] at feign.Feign$Builder.target(Feign.java:218) ~[feign-core-9.5.0.jar:na] at org.springframework.cloud.netflix.feign.HystrixTargeter.target(HystrixTargeter.java:39) ~[spring-cloud-netflix-core-1.4.4.RELEASE.jar:1.4.4.RELEASE] at org.springframework.cloud.netflix.feign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:211) ~[spring-cloud-netflix-core-1.4.4.RELEASE.jar:1.4.4.RELEASE] at org.springframework.cloud.netflix.feign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:232) ~[spring-cloud-netflix-core-1.4.4.RELEASE.jar:1.4.4.RELEASE] at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:178) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE] ... 68 common frames omitted
使用Feign的时候,如果参数中带有
@PathVariable形式的参数,则要用value=""标明对应的参数,否则会抛出IllegalStateException异常
如
@PutMapping("/disuseable/{sn}")ApiResponse disUseAble(@PathVariable String sn); // wrong-->
@PutMapping("/disuseable/{sn}")ApiResponse disUseAble(@PathVariable(value="sn") String sn); // right-->
@PutMapping("/disuseable/{sn}")ApiResponse disUseAble(@PathVariable("sn") String sn); // right一、FeignClient注解
FeignClient注解被@Target(ElementType.TYPE)修饰，表示FeignClient注解的作用目标在接口上
@FeignClient(name = "github-client", url = "https://api.github.com", configuration = GitHubExampleConfig.class)public interface GitHubClient { @RequestMapping(value = "/search/repositories", method = RequestMethod.GET) String searchRepo(@RequestParam("q") String queryStr);} 声明接口之后，在代码中通过@Resource注入之后即可使用。@FeignClient标签的常用属性如下：
- name：指定FeignClient的名称，如果项目使用了Ribbon，name属性会作为微服务的名称，用于服务发现
- url: url一般用于调试，可以手动指定@FeignClient调用的地址
- decode404:当发生http 404错误时，如果该字段位true，会调用decoder进行解码，否则抛出FeignException
- configuration: Feign配置类，可以自定义Feign的Encoder、Decoder、LogLevel、Contract
- fallback: 定义容错的处理类，当调用远程接口失败或超时时，会调用对应接口的容错逻辑，fallback指定的类必须实现@FeignClient标记的接口
- fallbackFactory: 工厂类，用于生成fallback类示例，通过这个属性我们可以实现每个接口通用的容错逻辑，减少重复的代码
path: 定义当前FeignClient的统一前缀
@FeignClient(name = "github-client", url = "https://api.github.com", configuration = GitHubExampleConfig.class, fallback = GitHubClient.DefaultFallback.class)public interface GitHubClient { @RequestMapping(value = "/search/repositories", method = RequestMethod.GET) String searchRepo(@RequestParam("q") String queryStr); /** * 容错处理类，当调用失败时，简单返回空字符串 */ @Component public class DefaultFallback implements GitHubClient { @Override public String searchRepo(@RequestParam("q") String queryStr) { return ""; } }} 在使用fallback属性时，需要使用@Component注解，保证fallback类被Spring容器扫描到,GitHubExampleConfig内容如下：
@Configurationpublic class GitHubExampleConfig { @Bean Logger.Level feignLoggerLevel() { return Logger.Level.FULL; }} 在使用FeignClient时，Spring会按name创建不同的ApplicationContext，通过不同的Context来隔离FeignClient的配置信息，在使用配置类时，不能把配置类放到Spring App Component scan的路径下，否则，配置类会对所有FeignClient生效.
二、Feign Client 和@RequestMapping
当前工程中有和Feign Client中一样的Endpoint时，Feign Client的类上不能用@RequestMapping注解否则，当前工程该endpoint http请求且使用accpet时会报404
Controller：
@RestController@RequestMapping("/v1/card")public class IndexApi { @PostMapping("balance") @ResponseBody public Info index() { Info.Builder builder = new Info.Builder(); builder.withDetail("x", 2); builder.withDetail("y", 2); return builder.build(); }} Feign Client
@FeignClient( name = "card", url = "http://localhost:7913", fallback = CardFeignClientFallback.class, configuration = FeignClientConfiguration.class)@RequestMapping(value = "/v1/card")public interface CardFeignClient { @RequestMapping(value = "/balance", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE) Info info(); } if @RequestMapping is used on class, when invoke http /v1/card/balance, like this :
如果 @RequestMapping注解被用在FeignClient类上，当像如下代码请求/v1/card/balance时，注意有Accept header：
Content-Type:application/jsonAccept:application/json POST http://localhost:7913/v1/card/balance
那么会返回 404。
如果不包含Accept header时请求，则是OK：
Content-Type:application/jsonPOST http://localhost:7913/v1/card/balance
或者像下面不在Feign Client上使用@RequestMapping注解,请求也是ok，无论是否包含Accept:
@FeignClient( name = "card", url = "http://localhost:7913", fallback = CardFeignClientFallback.class, configuration = FeignClientConfiguration.class) public interface CardFeignClient { @RequestMapping(value = "/v1/card/balance", method = RequestMethod.POST, produces = MediaType.APPLICATION_JSON_VALUE) Info info(); }
三、Feign请求超时问题
Hystrix默认的超时时间是1秒，如果超过这个时间尚未响应，将会进入fallback代码。而首次请求往往会比较慢（因为Spring的懒加载机制，要实例化一些类），这个响应时间可能就大于1秒了 解决方案有三种，以feign为例。 方法一 hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 5000 该配置是让Hystrix的超时时间改为5秒 方法二 hystrix.command.default.execution.timeout.enabled: false 该配置，用于禁用Hystrix的超时时间 方法三 feign.hystrix.enabled: false 该配置，用于索性禁用feign的hystrix。该做法除非一些特殊场景，不推荐使用。
参见：