版本使用的是SpringBoot: 2.1.0.RELEASE,SpringCloud: Greenwich.M1,OpenFeign: 2.1.0.M2
报错:
The bean 'xxxx.FeignClientSpecification', defined in null, could not be registered.
A bean with that name has already been defined in null and overriding is disabled.
Caused by: org.springframework.beans.factory.support.BeanDefinitionOverrideException:
Invalid bean definition with name xxxx.FeignClientSpecification' defined in null:
Cannot register bean definition [Generic bean: class [org.springframework.cloud.openfeign.FeignClientSpecification];
scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null;
factoryMethodName=null; initMethodName=null; destroyMethodName=null] for bean 'xxxx.FeignClientSpecification':
There is already [Generic bean: class [org.springframework.cloud.openfeign.FeignClientSpecification]; scope=; abstract=false; lazyInit=false;
autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false;
factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null] bound.
多个接口上的@FeignClient(“相同服务名”)会报错,overriding is disabled
,即出现了相同的Bean名。
在启动类中添加的@EnableFeignClients
中,可看到@import
引入FeignClientsRegistrar
实现注入。
核心是BeanDefinitionRegistry
注册FeignClients
public void registerFeignClients(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
ClassPathScanningCandidateComponentProvider scanner = getScanner();
scanner.setResourceLoader(this.resourceLoader);
Set<String> basePackages;
Map<String, Object> attrs = metadata
.getAnnotationAttributes(EnableFeignClients.class.getName());
AnnotationTypeFilter annotationTypeFilter = new AnnotationTypeFilter(
FeignClient.class);
final Class<?>[] clients = attrs == null ? null
: (Class<?>[]) attrs.get("clients");
if (clients == null || clients.length == 0) {
scanner.addIncludeFilter(annotationTypeFilter);
basePackages = getBasePackages(metadata);
}
else {
final Set<String> clientClasses = new HashSet<>();
basePackages = new HashSet<>();
for (Class<?> clazz : clients) {
basePackages.add(ClassUtils.getPackageName(clazz));
clientClasses.add(clazz.getCanonicalName());
}
AbstractClassTestingTypeFilter filter = new AbstractClassTestingTypeFilter() {
@Override
protected boolean match(ClassMetadata metadata) {
String cleaned = metadata.getClassName().replaceAll("\\$", ".");
return clientClasses.contains(cleaned);
}
};
scanner.addIncludeFilter(
new AllTypeFilter(Arrays.asList(filter, annotationTypeFilter)));
}
for (String basePackage : basePackages) {
Set<BeanDefinition> candidateComponents = scanner
.findCandidateComponents(basePackage);
for (BeanDefinition candidateComponent : candidateComponents) {
if (candidateComponent instanceof AnnotatedBeanDefinition) {
// verify annotated class is an interface
AnnotatedBeanDefinition beanDefinition = (AnnotatedBeanDefinition) candidateComponent;
AnnotationMetadata annotationMetadata = beanDefinition.getMetadata();
Assert.isTrue(annotationMetadata.isInterface(),
"@FeignClient can only be specified on an interface");
Map<String, Object> attributes = annotationMetadata
.getAnnotationAttributes(
FeignClient.class.getCanonicalName());
String name = getClientName(attributes);
registerClientConfiguration(registry, name,
attributes.get("configuration"));
registerFeignClient(registry, annotationMetadata, attributes);
}
}
}
}
其中registerFeignClient
方法需要装配BeanDefinitionBuilder对象,可以看到这里实际注入的是FeignClientFactoryBean
。
BeanDefinitionHolder
中传递了beanName,而它是等于annotationMetadata.getClassName();
,即被FeignClient注解的接口的全限定类名。
那么它的Bean名不会重复,错误原因并不是它引起的。
而注册configuration实际注入的是FeignClientSpecification
,这就是我们所报错的already存在的Bean。
可看到 beanName:name + "." + FeignClientSpecification.class.getSimpleName()
而其中的name参数,就是在registerFeignClients方法中通过getClientName()
获得。
String name = getClientName(attributes);
registerClientConfiguration(registry, name, attributes.get("configuration"));
在getClientName()
源码中,可以看到name就是@FeignClient注解中的serviceId,name,value。
beanName:name + "." + FeignClientSpecification.class.getSimpleName()
故而我们在使用相同名称的FeigClient注解时,注入到Ioc的是相同Bean名。
所以错误是由FeignClientSpecification类引起的。
在application.yml中配置:
spring:
main:
allow-bean-definition-overriding: true
在SpringBoot 2.1之前,这个配置默认就是true,而在2.1做了更改。
设置为true后,因为FeignClientSpecification的原因,FeignClient注解的configuration参数会被覆盖。
解决配置覆盖参考:
https://blog.csdn.net/neosmith/article/details/82349449
个人觉得Stackoverflow中有位大佬说的不错:
https://stackoverflow.com/questions/53103991/cant-stat-app-after-updating-springboot-from-2-0-6-release-to-2-1-0-release
别的情况下也可能会因为Bean名重复引起该错误,更佳的解决方案是尽可能避免去定义相同的Bean名。
而Feign远程调用服务因为业务需求出现在不同在接口上使用相同的服务名,将allow-bean-definition-overriding设置为true,如果在其他情况下没有重复Bean名,那么受影响的应该就只是Feign的configuration(然而configuration我都没另外做配置,覆盖也不影响- -)。
评论里大佬推荐在注解中添加 contextId 来区分,解决该问题。
@FeignClient(name="common-service", contextId = "example")