問題
在 Spring Cloud 中 微服務之間的調用會用到Feign，但是在默認情況下，Feign 調用遠程服務存在Header請求頭丟失問題。
解決方案
首先需要寫一個 Feign請求攔截器，通過實現RequestInterceptor接口,完成對所有的Feign請求,傳遞請求頭和請求參數。
Feign 請求攔截器
public class FeignBasicAuthRequestInterceptor implements RequestInterceptor {
private static final Logger logger = LoggerFactory.getLogger(FeignBasicAuthRequestInterceptor.class);
@Override
public void apply(RequestTemplate requestTemplate) {
ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder
.getRequestAttributes();
HttpServletRequest request = attributes.getRequest();
Enumeration<String> headerNames = request.getHeaderNames();
if (headerNames != null) {
while (headerNames.hasMoreElements()) {
String name = headerNames.nextElement();
String values = request.getHeader(name);
requestTemplate.header(name, values);
}
}
Enumeration<String> bodyNames = request.getParameterNames();
StringBuffer body =new StringBuffer();
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);
requestTemplate.body(body.toString());
logger.info("feign interceptor body:{}",body.toString());
}
}
}通過配置文件配置 讓 所有 FeignClient，來使用 FeignBasicAuthRequestInterceptor
feign:
client:
config:
default:
connectTimeout: 5000
readTimeout: 5000
loggerLevel: basic
requestInterceptors: com.leparts.config.FeignBasicAuthRequestInterceptor也可以配置讓 某個 FeignClient 來使用這個 FeignBasicAuthRequestInterceptor
feign:
client:
config:
xxxx: # 遠程服務名
connectTimeout: 5000
readTimeout: 5000
loggerLevel: basic
requestInterceptors: com.leparts.config.FeignBasicAuthRequestInterceptor經過測試，上面的解決方案可以正常的使用；但是出現了新的問題。
在轉發Feign的請求頭的時候, 如果開啟了Hystrix, Hystrix的默認隔離策略是Thread(線程隔離策略), 因此轉發攔截器內是無法獲取到請求的請求頭信息的。
可以修改默認隔離策略為信號量模式：
hystrix.command.default.execution.isolation.strategy=SEMAPHORE但信號量模式不是官方推薦的隔離策略;另一個解決方法就是自定義Hystrix的隔離策略。
自定義策略
HystrixConcurrencyStrategy 是提供給開發者去自定義hystrix內部線程池及其隊列，還提供了包裝callable的方法，以及傳遞上下文變量的方法。所以可以繼承了HystrixConcurrencyStrategy，用來實現了自己的併發策略。
@Component
public class FeignHystrixConcurrencyStrategy extends HystrixConcurrencyStrategy {
private static final Logger log = LoggerFactory.getLogger(FeignHystrixConcurrencyStrategy.class);
private HystrixConcurrencyStrategy delegate;
public FeignHystrixConcurrencyStrategy() {
try {
this.delegate = HystrixPlugins.getInstance().getConcurrencyStrategy();
if (this.delegate instanceof FeignHystrixConcurrencyStrategy) {
// 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 <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;
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();
}
}
}
}致此，Feign調用丟失請求頭的問題就解決的了 。
參考
https://blog.csdn.net/zl1zl2zl3/article/details/79084368
https://cloud.spring.io/spring-cloud-static/spring-cloud-openfeign/2.2.0.RC2/reference/html/
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