How can I avoid mutable variables in Scala when using ZipInputStreams and ZipOutpuStreams?

I'm trying to read a zip file, check that it has some required files, and then write all valid files out to another zip file. The basic introduction to java.util.zip has a lot of Java-isms and I'd love to make my code more Scala-native. Specifically, I'd like to avoid the use of vars. Here's what I have:

val fos = new FileOutputStream("new.zip");
val zipOut = new ZipOutputStream(new BufferedOutputStream(fos));

while (zipIn.available == 1) {
  val entry = zipIn.getNextEntry
  if (entryIsValid(entry)) {
    zipOut.putNewEntry(new ZipEntry("subdir/" + entry.getName())
    // read data into the data Array
    var data = Array[Byte](1024)
    var count = zipIn.read(data, 0, 1024)
    while (count != -1) {
      zipOut.write(data, 0, count)
      count = zipIn.read(data, 0, 1024)
    }
  }
  zipIn.close
}
zipOut.close

I should add that I'm using Scala 2.7.7.