参考书籍：《Hadoop实战》第二版 第9章:HDFS详解
1. HDFS基本操作
@ 出现的bug信息
@-@ WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
@-@ WARN hdfs.DFSClient: DFSInputStream has been closed already
@ Hadoop调试信息的开启与关闭
开启：export HADOOP_ROOT_LOGGER=DEBUG,console
关闭：export HADOOP_ROOT_LOGGER=INFO,console