Spring Cloud之Feign 转发请求头(header参数)

参考文章：

[SpringCloud-Feign] Feign转发请求头，(防止session失效)

feign调用session丢失解决方案

目录

1. 自定义feign隔离策略

2.设置feign拦截器,进行相应header的转发

2.1 示例一

2.2 示例一

---

1. 自定义feign隔离策略

package com.cloud.config;

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;
 */
@Component
public class FeignHystrixConcurrencyStrategyIntellif extends HystrixConcurrencyStrategy {
    Logger log = LoggerFactory.getLogger(this.getClass());

    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 instance = HystrixPlugins.getInstance();
            instance.registerConcurrencyStrategy(this);
            instance.registerCommandExecutionHook(commandExecutionHook);
            instance.registerEventNotifier(eventNotifier);
            instance.registerMetricsPublisher(metricsPublisher);
            instance.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();
            }
        }
    }
}

2.设置feign拦截器,进行相应header的转发

2.1 示例一

package com.cloud.interceptor;

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.springframework.beans.factory.annotation.Autowired;
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 static com.cloud.config.Constants.CLOUD_SESSION_ID;

/**
 * feign转发header参数
 * @author langpf 2018/12/19
 */
@Configuration
public class FeignRequestInterceptor implements RequestInterceptor {
    @Autowired
    HttpServletRequest httpServletRequest;

    public FeignRequestInterceptor() {
    }

    public void apply(RequestTemplate requestTemplate) {
        HttpServletRequest request = ((ServletRequestAttributes) 
                               RequestContextHolder.getRequestAttributes()).getRequest();
        String sessionId = RequestContextHolder.currentRequestAttributes().getSessionId();
        String sessionId2  = httpServletRequest.getSession().getId();
        String appkey0     = httpServletRequest.getHeader("appKey");
        String appkey      = request.getHeader("appKey");
        // String traceId     = request.getHeader("traceId");
        // String requestIp   = MyRequestUtil.getIpAddress(request);
        // String userAgent   = request.getHeader("User-agent");
        // String contentType = request.getHeader("Content-Type");
        //
        // requestTemplate.header("Content-Type", new String[]{contentType});
        // requestTemplate.header("User-agent", new String[]{userAgent});
        // requestTemplate.header("User-IP", new String[]{requestIp});
        // requestTemplate.header("traceId", new String[]{traceId});
        // requestTemplate.header("appKey", new String[]{appkey});

        requestTemplate.header(CLOUD_SESSION_ID, sessionId);
    }
}

2.2 示例一

转发所有header

package com.cloud.interceptor;

import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

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

/**
 * 转发所有header
 * @author langpf 2019/2/1
 */
// @Configuration // 注释掉, 不启用该拦截器; 如果启用, 直接打开注释即可
public class FeignRequestInterceptor3 implements RequestInterceptor {
    private final Logger logger = LoggerFactory.getLogger(getClass());

    @Override
    public void apply(RequestTemplate template) {
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        Enumeration headerNames = request.getHeaderNames();
        if (headerNames != null) {
            while (headerNames.hasMoreElements()) {
                String name = headerNames.nextElement();
                String values = request.getHeader(name);
                template.header(name, values);

            }
            logger.info("feign interceptor header:{}",template);
        }

        // 转发参数
        Enumeration bodyNames = request.getParameterNames();
        StringBuilder body = new StringBuilder();
        if (bodyNames != null) {
            while (bodyNames.hasMoreElements()) {
                String name = bodyNames.nextElement();
                String values = request.getParameter(name);
                body.append(name).append("=").append(values).append("&");
            }
        }
        if (body.length() != 0) {
            body.deleteCharAt(body.length() - 1);
            template.body(body.toString());
            //logger.info("feign interceptor body:{}",body.toString());
        }
    }
}