A reader read HDFS sequence file key by key. The sequence key and value types are both
BytesWritable.
Copy some code from
org.apache.hadoop.mapred.GuaguaSequenceAsTextRecordReader but to support
GuaguaRecordReader interface.
If use default constructor, user should also call
#initialize(GuaguaFileSplit) like in below:
this.setRecordReader(new GuaguaSequenceAsBinaryRecordReader());
this.getRecordReader().initialize(fileSplit);
or directly use other constructors:
this.setRecordReader(new GuaguaSequenceAsTextRecordReader(fileSplit));