通过Feign接口调用另一个模块的时候出了如下错了：PathVariable annotation was empty on param 0，Console报错如下：
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-06-23 09:28:33.097 ERROR 3548 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'testController': Unsatisfied dependency expressed through field 'testService'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.zeno.service.TestService': Unexpected exception during bean creation; nested exception is java.lang.IllegalStateException: PathVariable annotation was empty on param 0.
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:660) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:944) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918) ~[spring-context-5.3.10.jar:5.3.10]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.10.jar:5.3.10]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.5.5.jar:2.5.5]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) [spring-boot-2.5.5.jar:2.5.5]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:434) [spring-boot-2.5.5.jar:2.5.5]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:338) [spring-boot-2.5.5.jar:2.5.5]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1343) [spring-boot-2.5.5.jar:2.5.5]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1332) [spring-boot-2.5.5.jar:2.5.5]
at com.zeno.ConfigClientTestApplication.main(ConfigClientTestApplication.java:21) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.zeno.service.TestService': Unexpected exception during bean creation; nested exception is java.lang.IllegalStateException: PathVariable annotation was empty on param 0.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1380) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1300) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:657) ~[spring-beans-5.3.10.jar:5.3.10]
... 20 common frames omitted
Caused by: java.lang.IllegalStateException: PathVariable annotation was empty on param 0.
at feign.Util.checkState(Util.java:129) ~[feign-core-10.12.jar:na]
at org.springframework.cloud.openfeign.annotation.PathVariableParameterProcessor.processArgument(PathVariableParameterProcessor.java:51) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at org.springframework.cloud.openfeign.support.SpringMvcContract.processAnnotationsOnParameter(SpringMvcContract.java:299) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at feign.Contract$BaseContract.parseAndValidateMetadata(Contract.java:111) ~[feign-core-10.12.jar:na]
at org.springframework.cloud.openfeign.support.SpringMvcContract.parseAndValidateMetadata(SpringMvcContract.java:194) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at feign.Contract$BaseContract.parseAndValidateMetadata(Contract.java:62) ~[feign-core-10.12.jar:na]
at feign.ReflectiveFeign$ParseHandlersByName.apply(ReflectiveFeign.java:151) ~[feign-core-10.12.jar:na]
at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:49) ~[feign-core-10.12.jar:na]
at feign.Feign$Builder.target(Feign.java:269) ~[feign-core-10.12.jar:na]
at org.springframework.cloud.openfeign.DefaultTargeter.target(DefaultTargeter.java:30) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:373) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:421) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:396) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at org.springframework.cloud.openfeign.FeignClientsRegistrar.lambda$registerFeignClient$0(FeignClientsRegistrar.java:235) ~[spring-cloud-openfeign-core-3.0.4.jar:3.0.4]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.obtainFromSupplier(AbstractAutowireCapableBeanFactory.java:1249) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1191) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.10.jar:5.3.10]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.10.jar:5.3.10]
... 28 common frames omitted
Process finished with exit code 1Google了一下发现，@PathVariable 注解中的属性值value不能为空，我们只写@PathVariable，那value属性是默认为null的。所以需要将@PathVariable String name改成 @PathVariable(value=”name”) String name。此外，这个问题不会在Controller类上出现，但会在Feign接口上出现。也就是通常加了@FeignClient注解的接口上。