SpringCloudFeign转发请求头(防止session失效)的解决方案

获取：
@RequestMapping(value = "/api/test", method = RequestMethod.GET)
public String testFun(@RequestParam String name, @RequestHeader("uniqueId") String uniqueId) {
  if(uniqueId == null ){
     return "Must defined the uniqueId , it can not be null";
  }
  log.info(uniqueId, "begin testFun... ");
 return uniqueId;
}

@FeignClient(value = "DEMO-SERVICE")
public interface CallClient {

  /**
 * 访问DEMO-SERVICE服务的/api/test接口，通过注解将logId传递给下游服务
 */
 @RequestMapping(value = "/api/test", method = RequestMethod.GET)
  String callApiTest(@RequestParam(value = "name") String name, @RequestHeader(value = "uniqueId") String uniqueId);

}

import com.intellif.log.LoggerUtilI;
import feign.RequestInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;

/**
 * 自定义的请求头处理类，处理服务发送时的请求头；
 * 将服务接收到的请求头中的uniqueId和token字段取出来，并设置到新的请求头里面去转发给下游服务
 * 比如A服务收到一个请求，请求头里面包含uniqueId和token字段，A处理时会使用Feign客户端调用B服务
 * 那么uniqueId和token这两个字段就会添加到请求头中一并发给B服务；
 *
 * @author mozping
 * @version 1.0
 * @date 2018/6/27 14:13
 * @see FeignHeadConfiguration
 * @since JDK1.8
 */
@Configuration
public class FeignHeadConfiguration {
  private final LoggerUtilI logger = LoggerUtilI.getLogger(this.getClass().getName());

  @Bean
  public RequestInterceptor requestInterceptor() {
    return requestTemplate -> {
      ServletRequestAttributes attrs = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
      if (attrs != null) {
        HttpServletRequest request = attrs.getRequest();
        Enumeration headerNames = request.getHeaderNames();
        if (headerNames != null) {
          while (headerNames.hasMoreElements()) {
            String name = headerNames.nextElement();
            String value = request.getHeader(name);
            /**
             * 遍历请求头里面的属性字段，将logId和token添加到新的请求头中转发到下游服务
             * */
            if ("uniqueId".equalsIgnoreCase(name) || "token".equalsIgnoreCase(name)) {
              logger.debug("添加自定义请求头key:" + name + ",value:" + value);
              requestTemplate.header(name, value);
            } else {
              logger.debug("FeignHeadConfiguration", "非自定义请求头key:" + name + ",value:" + value + "不需要添加!");
            }
          }
        } else {
          logger.warn("FeignHeadConfiguration", "获取请求头失败！");
        }
      }
    };
  }

}

import com.netflix.hystrix.HystrixThreadPoolKey;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import com.netflix.hystrix.strategy.HystrixPlugins;
import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariable;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariableLifecycle;
import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;
import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;
import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
import com.netflix.hystrix.strategy.properties.HystrixProperty;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * 自定义Feign的隔离策略;
 * 在转发Feign的请求头的时候，如果开启了Hystrix，Hystrix的默认隔离策略是Thread(线程隔离策略)，因此转发拦截器内是无法获取到请求的请求头信息的，可以修改默认隔离策略为信号量模式：hystrix.command.default.execution.isolation.strategy=SEMAPHORE，这样的话转发线程和请求线程实际上是一个线程，这并不是最好的解决方法，信号量模式也不是官方最为推荐的隔离策略；另一个解决方法就是自定义Hystrix的隔离策略，思路是将现有的并发策略作为新并发策略的成员变量,在新并发策略中，返回现有并发策略的线程池、Queue；将策略加到Spring容器即可；
 *
 * @author mozping
 * @version 1.0
 * @date 2018/7/5 9:08
 * @see FeignHystrixConcurrencyStrategyIntellif
 * @since JDK1.8
 */
@Component
public class FeignHystrixConcurrencyStrategyIntellif extends HystrixConcurrencyStrategy {

  private static final Logger log = LoggerFactory.getLogger(FeignHystrixConcurrencyStrategyIntellif.class);
  private HystrixConcurrencyStrategy delegate;

  public FeignHystrixConcurrencyStrategyIntellif() {
    try {
      this.delegate = HystrixPlugins.getInstance().getConcurrencyStrategy();
      if (this.delegate instanceof FeignHystrixConcurrencyStrategyIntellif) {
        // Welcome to singleton hell...
        return;
      }
      HystrixCommandExecutionHook commandExecutiOnHook=
          HystrixPlugins.getInstance().getCommandExecutionHook();
      HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance().getEventNotifier();
      HystrixMetricsPublisher metricsPublisher = HystrixPlugins.getInstance().getMetricsPublisher();
      HystrixPropertiesStrategy propertiesStrategy =
          HystrixPlugins.getInstance().getPropertiesStrategy();
      this.logCurrentStateOfHystrixPlugins(eventNotifier, metricsPublisher, propertiesStrategy);
      HystrixPlugins.reset();
      HystrixPlugins.getInstance().registerConcurrencyStrategy(this);
      HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);
      HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
      HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);
      HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
    } catch (Exception e) {
      log.error("Failed to register Sleuth Hystrix Concurrency Strategy", e);
    }
  }

  private void logCurrentStateOfHystrixPlugins(HystrixEventNotifier eventNotifier,
                         HystrixMetricsPublisher metricsPublisher, HystrixPropertiesStrategy propertiesStrategy) {
    if (log.isDebugEnabled()) {
      log.debug("Current Hystrix plugins configuration is [" + "concurrencyStrategy ["
          + this.delegate + "]," + "eventNotifier [" + eventNotifier + "]," + "metricPublisher ["
          + metricsPublisher + "]," + "propertiesStrategy [" + propertiesStrategy + "]," + "]");
      log.debug("Registering Sleuth Hystrix Concurrency Strategy.");
    }
  }

  @Override
  public  Callable wrapCallable(Callable callable) {
    RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
    return new WrappedCallable<>(callable, requestAttributes);
  }

  @Override
  public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
                      HystrixProperty corePoolSize, HystrixProperty maximumPoolSize,
                      HystrixProperty keepAliveTime, TimeUnit unit, BlockingQueue workQueue) {
    return this.delegate.getThreadPool(threadPoolKey, corePoolSize, maximumPoolSize, keepAliveTime,
        unit, workQueue);
  }

  @Override
  public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey,
                      HystrixThreadPoolProperties threadPoolProperties) {
    return this.delegate.getThreadPool(threadPoolKey, threadPoolProperties);
  }

  @Override
  public BlockingQueue getBlockingQueue(int maxQueueSize) {
    return this.delegate.getBlockingQueue(maxQueueSize);
  }

  @Override
  public  HystrixRequestVariable getRequestVariable(HystrixRequestVariableLifecycle rv) {
    return this.delegate.getRequestVariable(rv);
  }

  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 {
        RequestContextHolder.setRequestAttributes(requestAttributes);
        return target.call();
      } finally {
        RequestContextHolder.resetRequestAttributes();
      }
    }
  }
}