HDFS 常用IO操作 其实我经常用的也就那几种，记住几种特定适合自己的就行
public static void testIOUtils() throws IOException {
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
Path p = new Path("/test/in/point");
FSDataInputStream fdis = fs.open(p);
IOUtils.copyBytes(fdis, System.out, conf,false);
IOUtils.closeStream(fdis);
fs.close();
}