Feign开启sentinel报错Cannotinvoke“org.springframework.cloud.openfeign.FeignClientFactoryBean.getFallback

系统管理员 2024-03-17 22:24 21阅读 0赞

## 指路 ##

建议直接看我的[博客][Link 1]

## 1.场景 ##

### **启动服务Application报错：** ###

Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.cloud.openfeign.FeignClientFactoryBean.getFallback()" because "feignClientFactoryBean" is null
    	at com.alibaba.cloud.sentinel.feign.SentinelFeign$Builder$1.create(SentinelFeign.java:93) ~[spring-cloud-starter-alibaba-sentinel-2022.0.0.0-RC1.jar:2022.0.0.0-RC1]
    	at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:59) ~[feign-core-12.1.jar:na]
    	at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:50) ~[feign-core-12.1.jar:na]
    	at feign.Feign$Builder.target(Feign.java:197) ~[feign-core-12.1.jar:na]
    	at org.springframework.cloud.openfeign.DefaultTargeter.target(DefaultTargeter.java:30) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    	at org.springframework.cloud.openfeign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:398) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    	at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:446) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    	at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:421) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    	at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:148) ~[spring-beans-6.0.7.jar:6.0.7]
    	... 31 common frames omitted

### **环境：** ###

springboot版本：3.0.5  
springcloud版本：2022.0.2  
spring-cloud-alibaba版本：2022.0.0.0-RC1

### **相关代码：** ###

#### order-service模块： ####

@MapperScan("cn.itcast.order.mapper")
    @SpringBootApplication
            // (scanBasePackages = "cn.itcast.feign")
    @EnableFeignClients(clients = UserClient.class)
            // ,defaultConfiguration = UserFeignConfig.class)
    public class OrderApplication {
        
    
        public static void main(String[] args) {
        
            SpringApplication.run(OrderApplication.class, args);
        }
    
    
        @Bean
        @LoadBalanced
        public RestTemplate restTemplate() {
        
            // todo 据说官方推荐RestTemplateBuilder
            return new RestTemplate();
        }

feign:
      sentinel:
        enabled: true

#### feign-api模块： ####

@FeignClient(value = "user-service", fallbackFactory = UserClientFallbackFactory.class,configuration = UserFeignConfig.class)
    public interface UserClient {
        
        @GetMapping("/user/{id}")
        Result findById(@PathVariable("id") Long id);
    }

@Slf4j
    public class UserClientFallbackFactory implements FallbackFactory<UserClient> {
        
    	@Override
    	public UserClient create(Throwable cause) {
        
    		//编写失败降级的处理逻辑
    		return new UserClient() {
        
    			@Override
    			public Result findById(Long id) {
        
    				log.error("查询用户异常",cause);
    				return new Result(Code.GET_ERR,new User());
    			}
    		};
    	}
    }

public class UserFeignConfig {
        
        //定义日志输出级别
        @Bean
        public Logger.Level feignLoggerLevel(){
        
            return Logger.Level.BASIC;
        }
    
        @Bean
        public UserClientFallbackFactory userClientFallbackFactory(){
        
            return new UserClientFallbackFactory();
        }

## 2.分析 ##

一开始以为是`@FeignClient`注解和`@EnableFeignClient`注解的`configuration`和`defaultConfiguration`注解无效的问题，导致`userClientFallbackFactory`没有被成功创建。  
打断点debug之后发现这个Bean已经被创建了，结合报错信息`FeignClientFactoryBean`是null，说明不是注解的问题。  
跑了下黑马的示例代码发现没有任何问题，于是把黑马代码环境换成我的环境，错误重现了。那就说明是环境问题。  
搜了下发现确实：完全一样的错误  
![img][]

## 3.解决方法 ##

根据官方回答，解决方法有两种：  
方法1.只要在配置文件里开启懒加载即可

spring:
      cloud:
        openfeign:
          lazy-attributes-resolution: true

方法2：  
升级`spring-cloud-alibaba`依赖版本

<dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-alibaba-dependencies</artifactId>
        
        <version>2022.0.0.0-RC2</version>
        <type>pom</type>
        <scope>import</scope>
    </dependency>

笑鼠 明明是bug，非要写在feature里  
![img2][]

[Link 1]: https://www.leviran.com/2023/07/585/
[img]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/14/f008a959d14a4aec8ddced5c9f448730.png
[img2]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/14/84a3bb0370ce44dabbcbff6a75719ff8.png