java - 为什么 HttpServletRequest 在 collection.parallelStream() 中为 null

Question

我使用的是 spring-boot 1.2.7，在尝试在 parallelStream().forEach(o -> addAddtionalData(id)) 中使用它时遇到了 NullPointerException，但是 Stream() 可以，我认为这可能是一个线程问题，但我无法很好地解释它，有人可以帮助指导我吗？

private void addAddtionalData(Long id){

    // request is null but not the first time loop in parallel stream
    HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
    boolean isSecure = request.isSecure();    
    // some code 
}

异常(exception):

[ERROR] org.apache.catalina.core.ContainerBase.[Tomcat].[localhost].[/].[dispatcherServlet] - Servlet.service() for 
servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause java.lang.NullPointerException: null
java.lang.NullPointerException: null
     at com.app.service.QuoteService.setAdditionalData(QuoteService.java:103) ~[classes/:na]
     at com.app.service.QuoteService.lambda$getAllQuotes$41(QuoteService.java:80) ~[classes/:na]
     at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184) ~[na:1.8.0_60]
     at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374) ~[na:1.8.0_60]
     at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_60]
     at java.util.stream.ForEachOps$ForEachTask.compute(ForEachOps.java:291) ~[na:1.8.0_60]
     at java.util.concurrent.CountedCompleter.exec(CountedCompleter.java:731) ~[na:1.8.0_60]
     at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) ~[na:1.8.0_60]
     at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) ~[na:1.8.0_60]
     at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692) ~[na:1.8.0_60]
     at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157) ~[na:1.8.0_60]

Answer 1

RequestContextHolder使用 ThreadLocal 来查找上下文对象。

Holder class to expose the web request in the form of a thread-bound RequestAttributes object.

使用并行流意味着您的代码在不同的线程中运行，因此没有上下文对象。

您应该在开始流处理之前获取 isSecure 值。