我正在嘗試在提交給集群的 spark 作業中使用 drools。這項工作將首先從 drools 服務器獲取 drools jar，然后初始化基礎和會話。我的代碼在 Spark 中執行時可以工作，但是在提交到 Spark 集群時會發生 NPE。這就是我的做法String url = "{my server address}/drools-wb/maven2/com/myspace/Project1/1.0.0/Project1-1.0.0.jar";KieServices ks = KieServices.Factory.get();//ERROR is in the below line ReleaseId releaseId = ks.newReleaseId("com.myspace", "Project1", "1.0.0"); KieRepository kr = ks.getRepository();UrlResource urlResource = (UrlResource) ks.getResources().newUrlResource(url);提交代碼后報錯：Exception in thread "main" java.lang.NullPointerException    at org.opencell.spark.jobs.TestWithDrools.main(TestWithDrools.java:47)    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)    at java.lang.reflect.Method.invoke(Method.java:498)    at org.apache.spark.deploy.JavaMainApplication.start(SparkApplication.scala:52)    at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:879)    at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:197)    at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:227)    at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:136)    at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)2018-08-29 10:08:09 INFO  ShutdownHookManager:54 - Shutdown hook called你有解決這個問題的想法嗎？