在spring-cloud项目中：
Feign拦截器：
@Component
@Slf4j
public class FeignAccessTokenRequestInterceptor implements RequestInterceptor {
@Override
public void apply(RequestTemplate requestTemplate) {
try {
HttpSevletRequest request = ((ServletRequestAttributes)RequestContextHolder.currentRequestAttributes()).getRequest();
requestTemplate.header("REQUEST-SOURCE", request.getHeader("REQUEST-SOURCE"));
} catch (Exception e) {
log.info("getRequest fail：{},ignore!", e.getMessage());
}
}
}
使用多线程异步调用微服务，在使用 RequestContextHolder.currentRequestAttributes()).getRequest() 来获取request信息，发现异步调用时，主线程结束后，子线程就获取不到request，会报以下错误信息。
getRequest fail：
No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request。
解决思路：
1.将主线程的request和session信息放进ThreadLocal里，透传到子线程再去获取。
2.在开启新线程之前，将servletRequestAttributes设置为子线程共享
继承 HystrixConcurrencyStrategy ：
@Component
@Slf4j
public class RequestAttributeStrategy extends HystrixConcurrencyStrategy {
public RequestAttributeStrategy() {
HystrixPlugins.reset();
HystrixPlugins.getInstance().registerConcurrencyStrategy(this);
}
@Override
public <T> Callable<T> wrapCallable(Callable<T> callable) {
RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
return new WrappedCallable<>(callable, requestAttributes);
}
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();
}
}
}
}
