Spring Cloud全解析：服务调用之多个FeignClient调用服务名称相同

name相同问题

在使用@FeignClient的时候，发现多个@FeignClient中的name相同就无法启动，当然了，这是因为bean名称重复了，创建bean的时候报的错，但是如何解决呢?

A bean with that name has already been defined and overriding is disabled

可以配置不同的contextId来进行解决

@FeignClient(name = "SPRINGCLOUD2-PROVIDER",contextId = "DeptClient",fallbackFactory = DeptClientFallBackFactory.class)
public interface DeptClient {

    @GetMapping(value = "/dept/get/{id}")
    CommonResult<Dept> get(@PathVariable("id") long id);

    @GetMapping("/timeout")
    String timeout();
}


@FeignClient(name = "SPRINGCLOUD2-PROVIDER",contextId = "DeptClient1",fallbackFactory = DeptClientFallBackFactory.class)
public interface DeptClient1 {

    @GetMapping(value = "/dept/get/{id}")
    CommonResult<Dept> get(@PathVariable("id") long id);

    @GetMapping("/timeout")
    String timeout();
}

为什么可以这样解决呢？

String name = getClientName(attributes);
registerClientConfiguration(registry, name,
      attributes.get("configuration"));

在FeignClientsRegistrar中进行@FeignClient注册时，对于bean的名称是调用getClientName(Map<String, Object> client)方法来获取的

private String getClientName(Map<String, Object> client) {
   if (client == null) {
      return null;
   }
   String value = (String) client.get("contextId");
   if (!StringUtils.hasText(value)) {
      value = (String) client.get("value");
   }
   if (!StringUtils.hasText(value)) {
      value = (String) client.get("name");
   }
   if (!StringUtils.hasText(value)) {
      value = (String) client.get("serviceId");
   }
   if (StringUtils.hasText(value)) {
      return value;
   }

   throw new IllegalStateException("Either 'name' or 'value' must be provided in @"
         + FeignClient.class.getSimpleName());
}

代码也比较简单，可以看到是先获取的contextId，如果配置了 contextId 就会用 contextId，如果没有配置就会取 value 然后是 name 最后是 serviceId

获取到clientName之后进行bean注册

private void registerClientConfiguration(BeanDefinitionRegistry registry, Object name,
      Object configuration) {
   BeanDefinitionBuilder builder = BeanDefinitionBuilder
         .genericBeanDefinition(FeignClientSpecification.class);
   builder.addConstructorArgValue(name);
   builder.addConstructorArgValue(configuration);
   registry.registerBeanDefinition(
         name + "." + FeignClientSpecification.class.getSimpleName(),
         builder.getBeanDefinition());
}

拼接的beanName就是clientName.FeignClientSpecification

参考文献

• name相同问题