Spring Cloud報錯Error creating bean with name 'requestMappingHandlerMapping'

如果我們使用Spring Cloud的Feign實現熔斷，首先需要自定義一個熔斷類，實現你的feign接口，然后實現方法，這些方法就是熔斷方法，最后需要在你的feign接口中指定fallback為自定義類

但是啟動過程中卻出現了org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-12-01 10:47:44.584 ERROR 10548 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'com.sjl.consumer.client.UserClient' method 
public abstract java.lang.String com.sjl.consumer.client.UserClient.getUser(java.lang.Integer)
to {[/user/{id}],methods=[GET]}: There is already 'userClientFallback' bean method
public java.lang.String com.sjl.consumer.client.UserClientFallback.getUser(java.lang.Integer) mapped.
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1694) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:573) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:548) ~[spring-context-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754) [spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386) [spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) [spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1242) [spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1230) [spring-boot-2.0.6.RELEASE.jar:2.0.6.RELEASE]
	at com.sjl.consumer.ServiceConsumerApplication.main(ServiceConsumerApplication.java:27) [classes/:na]
Caused by: java.lang.IllegalStateException: Ambiguous mapping. Cannot map 'com.sjl.consumer.client.UserClient' method 
public abstract java.lang.String com.sjl.consumer.client.UserClient.getUser(java.lang.Integer)
to {[/user/{id}],methods=[GET]}: There is already 'userClientFallback' bean method
public java.lang.String com.sjl.consumer.client.UserClientFallback.getUser(java.lang.Integer) mapped.
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.assertUniqueMethodMapping(AbstractHandlerMethodMapping.java:581) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:545) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:267) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lambda$detectHandlerMethods$1(AbstractHandlerMethodMapping.java:252) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_131]
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:250) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:219) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:189) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:136) ~[spring-webmvc-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1753) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1690) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]
	... 16 common frames omitted

如果啟動服務類出現了上述的錯誤，並且你的feign接口上定義了@RequestMapping("xxxx")全局訪問路徑，你只需要將其中的路徑移到方法的路徑上

例如我定義的

@FeignClient(value = "service-provider", fallback = UserClientFallback.class)//聲明這是一個Feign接口
@RequestMapping("/user")
public interface UserClient {

    @GetMapping("/{id}")
    String getUser(@PathVariable("id") Integer id);
}

將其改為

@FeignClient(value = "service-provider", fallback = UserClientFallback.class)//聲明這是一個Feign接口
//@RequestMapping("/user")
public interface UserClient {

    @GetMapping("/user/{id}")
    String getUser(@PathVariable("id") Integer id);
}

即可啟動成功