测试代码

    /**
     * 自定义 - 线程池
     */
    private static final ThreadPoolExecutor executorService = new ThreadPoolExecutor(50, 200,
            180L, TimeUnit.SECONDS,
            new LinkedBlockingQueue<Runnable>(3000), new ThreadFactory() {

        final ThreadFactory defaultFactory = Executors.defaultThreadFactory();

        @Override
        public Thread newThread(Runnable r) {
            Thread thread = defaultFactory.newThread(r);
            thread.setName("testRequest - " + thread.getName());
            return thread;
        }
    }, new ThreadPoolExecutor.CallerRunsPolicy());


    private String getToken() {
        ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        if (requestAttributes == null) {
            return null;
        }
        HttpServletRequest currentRequest = requestAttributes.getRequest();
        return currentRequest.getHeader("token");
    }

    @SneakyThrows
    public void test() {
        String token = getToken();
        log.info("测试1：主线程 mainThreadToken = {}", token);
        log.info("----------------------------------------");

        // 子线程1 Future
        Future<String> future1 = CompletableFuture.supplyAsync(() -> {
            // 子线程中获取token
            String childThreadToken = getToken();
            log.info("测试2：子线程 childThreadToken = {}", childThreadToken);
            return childThreadToken;
        }, executorService);
        future1.get();
        log.info("----------------------------------------");

        // 子线程2
        Arrays.asList(1, 2, 3, 4).parallelStream().forEach(t -> {
            // 子线程中获取token
            String childThreadToken = getToken();
            log.info("测试3：子线程 childThreadToken = {}", childThreadToken);
        });
        log.info("----------------------------------------");

        // 子线程 嵌套 子线程
        Future<String> future2 = CompletableFuture.supplyAsync(() -> {
            Arrays.asList(1, 2, 3, 4).parallelStream().forEach(t -> {
                // 子线程中获取token
                String childThreadToken = getToken();
                log.info("测试4：子线程 childThreadToken = {}", childThreadToken);
            });
            return null;
        }, executorService);
        future2.get();
        log.info("----------------------------------------");

        // 子线程 嵌套 子线程 传递 header 方式1
        RequestAttributes attributes = RequestContextHolder.getRequestAttributes();
        Future<String> future3 = CompletableFuture.supplyAsync(() -> {
            try {
                RequestContextHolder.setRequestAttributes(attributes);
                Arrays.asList(1, 2, 3, 4).parallelStream().forEach(t -> {
                    RequestContextHolder.setRequestAttributes(attributes);
                    // 子线程中获取token
                    String childThreadToken = getToken();
                    log.info("方式1：子线程 childThreadToken = {}", childThreadToken);
                });
                return null;
            } finally {
                RequestContextHolder.resetRequestAttributes();
            }
        }, executorService);
        future3.get();
        log.info("----------------------------------------");

        // 子线程 嵌套 子线程 传递 header 方式2
        Future<String> future4 = CompletableFuture.supplyAsync(() -> {
            try {
                Arrays.asList(1, 2, 3, 4).parallelStream().forEach(t -> {
                    // 子线程中获取token
                    String childThreadToken = TokenInheritableThreadLocal.getToken();
                    log.info("方式2：子线程 childThreadToken = {}", childThreadToken);
                });
                return null;
            } finally {
                RequestContextHolder.resetRequestAttributes();
            }
        }, executorService);
        future4.get();
        log.info("----------------------------------------");
    }

测试结果

--------------------------------------------------------------------------------
测试1：主线程 http-nio-8083-exec-3，mainThreadToken = 123456
--------------------------------------------------------------------------------
测试2：子线程 testRequest - pool-1-thread-1，childThreadToken = null
--------------------------------------------------------------------------------
测试3：子线程 http-nio-8083-exec-3，childThreadToken = 123456
测试3：子线程 ForkJoinPool.commonPool-worker-2，childThreadToken = null
测试3：子线程 ForkJoinPool.commonPool-worker-9，childThreadToken = null
测试3：子线程 ForkJoinPool.commonPool-worker-2，childThreadToken = null
--------------------------------------------------------------------------------
测试4：子线程 testRequest - pool-1-thread-2，childThreadToken = null
测试4：子线程 ForkJoinPool.commonPool-worker-4，childThreadToken = null
测试4：子线程 ForkJoinPool.commonPool-worker-11，childThreadToken = null
测试4：子线程 ForkJoinPool.commonPool-worker-2，childThreadToken = null
--------------------------------------------------------------------------------
方式1：子线程 ForkJoinPool.commonPool-worker-2，childThreadToken = 123456
方式1：子线程 ForkJoinPool.commonPool-worker-4，childThreadToken = 123456
方式1：子线程 ForkJoinPool.commonPool-worker-11，childThreadToken = 123456
方式1：子线程 testRequest - pool-1-thread-3，childThreadToken = 123456
--------------------------------------------------------------------------------
方式2：子线程 testRequest - pool-1-thread-4，childThreadToken = 123456
方式2：子线程 ForkJoinPool.commonPool-worker-2，childThreadToken = 123456
方式2：子线程 ForkJoinPool.commonPool-worker-11，childThreadToken = 123456
方式2：子线程 ForkJoinPool.commonPool-worker-4，childThreadToken = 123456
--------------------------------------------------------------------------------

分析

1. parallelStream() 也会导致请求头丢失，没丢失的是其中一个并行的主线程 http-nio-8083-exec-3
2. 通过RequestContextHolder.setRequestAttributes(attributes); 可以透传header，但是麻烦
3. InheritableThreadLocal 可以绑定父线程的变量，子线程也可以获取，使用方便

最佳解决方案

• TokenInheritableThreadLocal

public class TokenInheritableThreadLocal {

    private TokenInheritableThreadLocal() {
    }

    public static final InheritableThreadLocal<String> THREAD_LOCAL = new InheritableThreadLocal() {
        @Override
        protected String initialValue() {
            return null;
        }
    };

    public static String getToken() {
        return THREAD_LOCAL.get();
    }

    public static void remove() {
        THREAD_LOCAL.remove();
    }

}

• TokenInterceptor

public class TokenInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        TokenInheritableThreadLocal.THREAD_LOCAL.set(request.getHeader("token"));
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }

    /**
     * 本次调用结束了，就可以释放threadLocal资源避免内存泄漏的情况发生
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        TokenInheritableThreadLocal.THREAD_LOCAL.remove();
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }

}

• CommonWebAppConfigurer

@Configuration
public class CommonWebAppConfigurer implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new TokenInterceptor());
    }
}