@FeignClient注解中屬性contextId的使用說明

更新時間：2022年06月18日 11:13:03 作者：goodjob110

這篇文章主要介紹了@FeignClient注解中屬性contextId的使用說明，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

一、概述

如果我們使用Feign定義了兩個接口，但是目標服務是同一個，那么在SpringBoot啟動時就會遇到一個問題：

Description:
The bean 'xxxxxxxx.FeignClientSpecification', defined in null, could not be registered. A bean with that name has already been defined in null and overriding is disabled.
Action:
Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

二、解決方案

2.1 方案1

修改yml配置：spring.main.allow-bean-definition-overriding=true

spring:
  main:
    allow-bean-definition-overriding: true

2.2 方案2

在每個Feign的接口中，在注解上加 contextId屬性

contextId在Feign Client的作用是在注冊Feign Client Configuration的時候需要一個名稱，名稱是通過getClientName方法獲取的

@FeignClient(name = "sale-service",contextId= "saleservice1")
 
public interface saleClient{
 
    @RequestMapping(value = "/sale/add", method = RequestMethod.GET)
 
    String add(@RequestParam("saleNum") String queryStr);
 
}

備注：contextId= "名稱" 中的名稱，不能用“_”會報錯，可以用“-”

三、源代碼分析

包名：spring-cloud-openfeign-core-2.2.5.RELEASE.jar
類路徑：org.springframework.cloud.openfeign.FeignClientsRegistrar

相關代碼1

 private void registerFeignClient(BeanDefinitionRegistry registry, AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
        String className = annotationMetadata.getClassName();
        BeanDefinitionBuilder definition = BeanDefinitionBuilder.genericBeanDefinition(FeignClientFactoryBean.class);
        this.validate(attributes);
        definition.addPropertyValue("url", this.getUrl(attributes));
        definition.addPropertyValue("path", this.getPath(attributes));
        String name = this.getName(attributes);
        definition.addPropertyValue("name", name);
        String contextId = this.getContextId(attributes);
        definition.addPropertyValue("contextId", contextId);
        definition.addPropertyValue("type", className);
        definition.addPropertyValue("decode404", attributes.get("decode404"));
        definition.addPropertyValue("fallback", attributes.get("fallback"));
        definition.addPropertyValue("fallbackFactory", attributes.get("fallbackFactory"));
        definition.setAutowireMode(2);
        String alias = contextId + "FeignClient";
        AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
        beanDefinition.setAttribute("factoryBeanObjectType", className);
        boolean primary = (Boolean)attributes.get("primary");
        beanDefinition.setPrimary(primary);
        String qualifier = this.getQualifier(attributes);
        if (StringUtils.hasText(qualifier)) {
            alias = qualifier;
        }
 
        BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className, new String[]{alias});
        BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
    }

代碼截圖：