Spring Cloud Feign fallback打印出真实的错误信息

https://www.cnblogs.com/qq931399960/p/15846408.html

根据上述操作，虽然发生错误后，可以执行fallback，但具体的错误信息后端没有打印，具体的错误信息有时候很重要，可以帮助我们来定位错误的根本原因

根据Spring Cloud OpenFeign官方文档"1.6. Feign Spring Cloud CircuitBreaker Fallbacks"，实现该功能也很简单

在本例中，将之前使用的feignclient注解的属性fallback改为使用fallbackFactory，并且callback实现类改为ConsumerServiceCallbackFactory

feign接口

package com.demo.service;

import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import com.demo.entity.ResultEntity;
import com.demo.service.callback.ConsumerServiceCallbackFactory;

@FeignClient(name = "SERVICE-PROVIDER", fallbackFactory = ConsumerServiceCallbackFactory.class)
public interface ConsumerService {

    /**
     * 此处不能返回Object，要么返回String，要么返回存在get set方法的实体对象或者map
     * @param id
     * @return
     */
    @RequestMapping("/getData/{id}")
    ResultEntity getData(@PathVariable String id);
} 

fallback factory

package com.demo.service.callback;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.openfeign.FallbackFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.PathVariable;

import com.demo.entity.ResultEntity;
import com.demo.service.ConsumerService;

@Component
public class ConsumerServiceCallbackFactory implements FallbackFactory<ConsumerServiceCallBack>{

    private Logger logger = LoggerFactory.getLogger(ConsumerServiceCallbackFactory.class);
    @Override
    public ConsumerServiceCallBack create(Throwable e) {
        logger.error("",e);
        return new ConsumerServiceCallBack();
    }

}
class ConsumerServiceCallBack implements ConsumerService{

    private Logger logger = LoggerFactory.getLogger(ConsumerServiceCallBack.class);
    
    @Override
    public ResultEntity getData(@PathVariable String id) {
        logger.error("call back id: {}", id);
        return new ResultEntity(false, "error");
    }
}

测试

将服务提供者服务线程休眠一段时间，模拟出read timeout，重启服务提供者合并服务消费者，再次访问：http://127.0.0.1:8081/getData/10

浏览器显示

后端打印出异常信息

2022-01-26 15:05:48.239 ERROR 193180 --- [nio-8081-exec-4] c.d.s.c.ConsumerServiceCallbackFactory   : 

java.util.concurrent.TimeoutException: TimeLimiter 'ConsumerService#getData(String)' recorded a timeout exception.
	at java.util.concurrent.FutureTask.get(Unknown Source) ~[na:1.8.0_172]
	at io.github.resilience4j.timelimiter.internal.TimeLimiterImpl.lambda$decorateFutureSupplier$0(TimeLimiterImpl.java:46) ~[resilience4j-timelimiter-1.7.0.jar:1.7.0]
	at io.github.resilience4j.circuitbreaker.CircuitBreaker.lambda$decorateCallable$3(CircuitBreaker.java:171) ~[resilience4j-circuitbreaker-1.7.0.jar:1.7.0]
	at io.vavr.control.Try.of(Try.java:75) ~[vavr-0.10.2.jar:na]

从异常信息可以看出发生了超时