场景：web端调用A服务，A服务调用B服务
A服务将web端通过header中的token解析，获取到user信息，A调用B服务时需要将token或者用户信息传递给B服务
暴力解决的方案为：直接把user作为一个对象传递就可以了，但是这种做法导致每个接口都需要传递user对象，非常麻烦
我们的做法是将token或者user信息统一封装在feign的header中传递给B服务，如果没有开启hystrix，这种方式一点问题也没有，但是开启了hytrix后，出现了大问题！！
package xxx.xxx.xxx;
import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
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;
@Configuration
public class FeignBasicAuthRequestInterceptor implements RequestInterceptor {
private static final Logger log = LoggerFactory.getLogger(FeignBasicAuthRequestInterceptor.class);
@Override
public void apply(RequestTemplate requestTemplate) {
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);
if(name.equals("Authorization")){
log.info(values);
}
requestTemplate.header(name, values);
}
}
}
}
我们定义一个FeignInterceptor实现RequestInterceptor，在通过feign调用的时候，会自动进入此拦截器，在此拦截器中，将token或者user信息放置到header中
2、重写HystrixConcurrencyStrategy开启hystrix后，Hystrix内部提供了两种模式执行逻辑：信号量、线程池。但是，spring cloud官方是不推荐信号量这种方式的，我们只能采用线程池这种方式。
线程池这种方式，是开启了另外一个线程（线程隔离）来进行feign调用的，主线程中的request是传递不到新开启线程中的，所以，我们要重写HystrixConcurrencyStrategy(并发策略)
package xxx.xxx.xxx;
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 lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Configuration;
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;
@Slf4j
@Configuration
public class FeignHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {
private HystrixConcurrencyStrategy delegate;
public FeignHystrixConcurrencyStrategy() {
try {
this.delegate = HystrixPlugins.getInstance().getConcurrencyStrategy();
if (this.delegate instanceof FeignHystrixConcurrencyStrategy) {
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);
//重置HystrixPlugins再重新填充 否则会报 Another strategy was already registered.
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();
}
}
}
}
测试：
场景：openfeign接口写在服务提供方即服务B中，服务A引入服务B的feign接口模块
1.在服务调用方即服务A配置这两个文件，可以实现header透传
2.在服务提供方即服务B配置这两个文件，可以实现header透传
3.服务调用方即服务A配置第二步，服务提供方配置第一步，也可以实现header透传
3.服务调用方即服务A配置第一步，服务提供方配置第二步，也可以实现header透传
