uncompress and read gzip file in scala

Question

In Scala, how does one uncompress the text contained in file.gz so that it can be processed? I would be happy with either having the contents of the file stored in a variable, or saving it as a local file so that it can be read in by the program after.

Specifically, I am using Scalding to process compressed log data, but Scalding does not define a way to read them in FileSource.scala.

Answer 1

Here's my version:

import java.io.BufferedReader
import java.io.InputStreamReader
import java.util.zip.GZIPInputStream
import java.io.FileInputStream

class BufferedReaderIterator(reader: BufferedReader) extends Iterator[String] {
  override def hasNext() = reader.ready
  override def next() = reader.readLine()
}

object GzFileIterator {
  def apply(file: java.io.File, encoding: String) = {
    new BufferedReaderIterator(
      new BufferedReader(
        new InputStreamReader(
          new GZIPInputStream(
            new FileInputStream(file)), encoding)))
  }
}

Then do:

val iterator = GzFileIterator(new java.io.File("test.txt.gz"), "UTF-8")
iterator.foreach(println)