关于开启熔断之后，请求一直报401异常错误的问题

   附上原文作者：  http://www.itmuch.com/spring-cloud-sum/hystrix-threadlocal/

#服务熔断
feign.hystrix.enabled = true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds = 5000

 

 这是我在公司开发项目时配置熔断的时候踩的一个坑，接下来贴上来一般常用的拦截器所用的一段代码

  

ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();

    当你开启熔断后会遇到一个问题就是attributes取到的上下文为空，这是因为Hystrix有隔离策略：THREAD和SEMAPHORE，所以当你的隔离策略为THREAD的时候是拿不到Threadlocal里面的值的。

    这边我用了两种方法直接贴上我的解决方案：

    第一种：

    直接添加配置修改默认的隔离策略：

    

#服务熔断
feign.hystrix.enabled = true
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds = 5000
hystrix.command.default.execution.isolation.strategy = SEMAPHORE

   修改配置文件把默认策略改成SEMAPHORE就能拿到ThreadLoacl里的值了当然不推荐这样做

    第二种：

    创建一个重写类

package com.jusda.common.Interceptor;

import com.netflix.hystrix.strategy.HystrixPlugins;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;

import java.util.concurrent.Callable;

/**
 * @author wanglinfeng
 * @version 1.0
 * @className RequestAttributeHystrixConcurrencyStrategy
 * @description 获取开启Hystrix后的上下文封装
 * @date 2019/8/12 9:32
 */
public class RequestAttributeHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {
    private static final Logger logger= LoggerFactory.getLogger(RequestAttributeHystrixConcurrencyStrategy.class);
    public RequestAttributeHystrixConcurrencyStrategy(){
        HystrixPlugins.reset();
        HystrixPlugins.getInstance().registerConcurrencyStrategy(this);
    }

    /**
     * 装饰线程hystrix callable
     *
     * @return {@link Callable}
     */

    @Override
    public  Callable wrapCallable(Callable callable ){
        RequestAttributes requestAttribute = RequestContextHolder.getRequestAttributes();
        return new WrappedCallable<>(callable,requestAttribute);
    }
    static class WrappedCallable implements Callable{
        private final Callable target;
        private final RequestAttributes requestAttributes;
        public WrappedCallable(Callable target,RequestAttributes requestAttributes){
            this.target = target;
            this.requestAttributes = requestAttributes;
        }
        @Override
        public T call() throws Exception{
            try {
                //在调用call方法前，我们可以将当前上下文信息放入
                RequestContextHolder.setRequestAttributes(requestAttributes);
                //call()传播上下文信息
                return target.call();
            }finally {
                RequestContextHolder.resetRequestAttributes();
            }
        }
    }
}

如图所示自定义并发策略重写wrapCallable继承HystrixConcurrencyStrategy

此代码经测试能正常工作。