HBase - Hadoop: The Definitive Guide - page 718

@Override
public int run ( String [] args ) throws Exception {
if ( args . length != 1 ) {
System . err . println ( "Usage: HBaseTemperatureImporter <input>" );
return - 1 ;
}
Job job = new Job ( getConf (), getClass (). getSimpleName ());
job . setJarByClass ( getClass ());
FileInputFormat . addInputPath ( job , new Path ( args [ 0 ]));
job . getConfiguration (). set ( TableOutputFormat . OUTPUT_TABLE ,
"observations" );
job . setMapperClass ( HBaseTemperatureMapper . class );
job . setNumReduceTasks ( 0 );
job . setOutputFormatClass ( TableOutputFormat . class );
return job . waitForCompletion ( true ) ? 0 : 1 ;
}
public static void main ( String [] args ) throws Exception {
int exitCode = ToolRunner . run ( HBaseConfiguration . create (),
new HBaseTemperatureImporter (), args );
System . exit ( exitCode );
}
}
HBaseTemperatureImporter has a nested class named HBaseTemperat-
ureMapper that is like the MaxTemperatureMapper class from Chapter 6 . The out-
er class implements Tool and does the setup to launch the map-only job. HBaseTem-
peratureMapper takes the same input as MaxTemperatureMapper and does the
same parsing — using the NcdcRecordParser introduced in Chapter 6 — to check for
valid temperatures. But rather than writing valid temperatures to the output context, as
MaxTemperatureMapper does, it creates a Put object to add those temperatures to
the observations HBase table, in the data:airtemp column. (We are using static
constants for data and airtemp , imported from the HBaseTemperatureQuery
class described later.)
The row key for each observation is created in the makeObservationRowKey()
method on RowKeyConverter from the station ID and observation time:
public class RowKeyConverter {
private static final int STATION_ID_LENGTH = 12 ;
/**
* @return A row key whose format is: <station_id>