map.input.file in 20.1

[David Hawthorne]

I'm trying to get the name of the file that the map job is operating on out of 
the Context passed to the setup function.  It's proving harder than seems 
proper.

I've found several links via google on this topic, but I've seen no responses 
to previous questions.

We have this from July 17, 2009:

http://www.mail-archive.com/common-user@hadoop.apache.org/msg00535.html

I attempted that solution and javac complained about using a deprecated API.

It's very clearly spelled out in this doc:

http://hadoop.apache.org/common/docs/r0.20.1/mapred_tutorial.html

and yet the example source code for 20.1 is still using the mapred.* 
(deprecated) API that the prior link used as well.

For the record, here's what I've tried, in the hopes that someone will just 
paste back a working solution:

import java.io.IOException;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.reduce.IntSumReducer;
import org.apache.hadoop.mapred.FileSplit;

public class Foo {
        public static class FooMapper extends Mapper<Object, Text, Text, 
IntWritable> {

                private org.apache.hadoop.io.Text input_file;

                public void setup (Context context) {
                        Configuration conf = context.getConfiguration();
 
                        //
                        // fails to compile due to use of deprecated mapred API:
                        //
                        FileSplit fileSplit = 
(FileSplit)context.getInputSplit();
                        String input_fname = fileSplit.getPath().toString();
                        input_file.set(input_fname);

                        //
                        // results in null pointer exception because conf.get 
returns null:
                        //
                        // input_file.set(conf.get("map.input.file"));
                }
        }
}