SpringCloud Feign转发请求头(防止session失效)的解决方案
作者:学圆惑边
微服务开发中经常有这样的需求,公司自定义了通用的请求头,需要在微服务的调用链中转发,比如在请求头中加入了token,或者某个自定义的信息uniqueId,总之就是自定义的一个键值对的东东,A服务调用B服务,B服务调用C服务,这样通用的东西如何让他在一个调用链中不断地传递下去呢?以A服务为例:
方案1
最傻的办法,在程序中获取,调用B的时候再转发,怎么获取在Controller中国通过注解获取,或者通过request对象获取,这个不难,在请求B服务的时候,通过注解将值放进去即可;简代码如下:
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; }
然后A使用Feign调用B服务的时候,传过去:
@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); }
方案弊端:毫无疑问,这方案不好,因为对代码有侵入,需要开发人员没次手动的获取和添加,因此舍弃
方案2
服务通过请求拦截器,在请求从A发送到B之后,在拦截器内将自己需要的东东加到请求头:
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<String> 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!"); } } }; } }
网上很多关于这种方法的博文或者资料,大同小异,但是有一个问题,在开启熔断器之后,这里的attrs就是null,因为熔断器默认的隔离策略是thread,也就是线程隔离,实际上接收到的对象和这个在发送给B不是一个线程,怎么办?有一个办法,修改隔离策略hystrix.command.default.execution.isolation.strategy=SEMAPHORE,改为信号量的隔离模式,但是不推荐,因为thread是默认的,而且要命的是信号量模式,熔断器不生效,比如设置了熔断时间hystrix.command.default.execution.isolation.semaphore.timeoutInMilliseconds=5000,五秒,如果B服务里面sleep了10秒,非得等到B执行完毕再返回,因此这个方案也不可取;但是有什么办法可以在默认的Thread模式下让拦截器拿到上游服务的请求头?自定义策略:代码如下:
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 <T> Callable<T> wrapCallable(Callable<T> callable) { RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes(); return new WrappedCallable<>(callable, requestAttributes); } @Override public ThreadPoolExecutor getThreadPool(HystrixThreadPoolKey threadPoolKey, HystrixProperty<Integer> corePoolSize, HystrixProperty<Integer> maximumPoolSize, HystrixProperty<Integer> keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> 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<Runnable> getBlockingQueue(int maxQueueSize) { return this.delegate.getBlockingQueue(maxQueueSize); } @Override public <T> HystrixRequestVariable<T> getRequestVariable(HystrixRequestVariableLifecycle<T> rv) { return this.delegate.getRequestVariable(rv); } static class WrappedCallable<T> implements Callable<T> { private final Callable<T> target; private final RequestAttributes requestAttributes; public WrappedCallable(Callable<T> 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(); } } } }
然后使用默认的熔断器隔离策略,也可以在拦截器内获取到上游服务的请求头信息了;
这里参考的博客,感谢这位大牛:https://blog.csdn.net/Crystalqy/article/details/79083857
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