目录

• 推荐公众号
• 问题场景
• 正文
• 异常信息

推荐公众号

有彩蛋哦!!!(或者公众号内点击网赚获取彩蛋)

问题场景

刚入开发职业时，上级会交代很多事情，例如：功能要自测!!!
这个很重要，今天这个问题也是因为开发人员不自测，就把代码发到测试环境，导致功能异常，这种低级错误以后要杜绝

正文

异常信息

Fallback class must implement the interface
 annotated by @FeignClient

 在feign注册的时候会校验fallback的class是不是接口 如果是接口就会抛出这个异常
 private void registerFeignClient(BeanDefinitionRegistry registry,
			AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
		String className = annotationMetadata.getClassName();
		BeanDefinitionBuilder definition = BeanDefinitionBuilder
				.genericBeanDefinition(FeignClientFactoryBean.class);
		校验
		validate(attributes);
		definition.addPropertyValue("url", getUrl(attributes));
		definition.addPropertyValue("path", getPath(attributes));
		String name = getName(attributes);
		definition.addPropertyValue("name", name);
		String contextId = 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(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);

		String alias = contextId + "FeignClient";
		AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();

		boolean primary = (Boolean) attributes.get("primary"); // has a default, won't be
																// null

		beanDefinition.setPrimary(primary);

		String qualifier = getQualifier(attributes);
		if (StringUtils.hasText(qualifier)) {
			alias = qualifier;
		}

		BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className,
				new String[] { alias });
		BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
	}
	
	private void validate(Map<String, Object> attributes) {
		AnnotationAttributes annotation = AnnotationAttributes.fromMap(attributes);
		// This blows up if an aliased property is overspecified
		// FIXME annotation.getAliasedString("name", FeignClient.class, null);
		简要fallback
		validateFallback(annotation.getClass("fallback"));
		validateFallbackFactory(annotation.getClass("fallbackFactory"));
	}
	static void validateFallback(final Class clazz) {
	如果是接口抛出异常
		Assert.isTrue(!clazz.isInterface(),
				"Fallback class must implement the interface annotated by @FeignClient");
	}
public static void isTrue(boolean expression, String message) {
		if (!expression) {
			throw new IllegalArgumentException(message);
		}
	}