How to get the input file name in the mapper in a Hadoop program?

Question

How I can get the name of the input file within a mapper? I have multiple input files stored in the input directory, each mapper may read a different file, and I need to kno

Answer 1

Noticed on Hadoop 2.4 and greater using the old api this method produces a null value

String fileName = new String();
public void configure(JobConf job)
{
   fileName = job.get("map.input.file");
}

Alternatively you can utilize the Reporter object passed to your map function to get the InputSplit and cast to a FileSplit to retrieve the filename

public void map(LongWritable offset, Text record,
        OutputCollector out, Reporter rptr)
        throws IOException {

    FileSplit fsplit = (FileSplit) rptr.getInputSplit();
    String inputFileName = fsplit.getPath().getName();
    ....
}