spark启动失败：requirement failed: No output operations registered, so nothing to execute
报错：Exception in thread "main" java.lang.IllegalArgumentException: requirement failed: No output operations registered, so nothing to execute原因：在start后，没有触发spark的流数据动作，任意一个触发DStream的动作即可解决该问题，比如JavaReceiverInputDStream的：print()...
