How to decompress a gzipped data in a byte array?

Question

I have a class which has a method that is receiving an object as a parameter. This method is invoked via RMI.

public RMIClass extends Serializable {
    public RMIMethod(MyFile file){
        // do stuff
    }
}

MyFile has a property called "body", which is a byte array.

public final class MyFile implements Serializable {

    private byte[] body = new byte[0];
    //.... 

    public byte[] getBody() {
        return body;
    }
    //....
}

This property holds the gzipped data of a file that was parsed by another application.

I need to decompress this byte array before performing further actions with it.

All the examples I see of decompressing gzipped data assume that I want to write it to the disk and create a physical file, which I do not.

How do I do this?

Thanks in advance.

Answer 1

Wrap your byte array with a ByteArrayInputStream and feed it into a GZipInputStream

Answer 2

JDK 9+

  private byte[] gzipUncompress(byte[] compressedBytes) throws IOException {
    try (InputStream inputStream = new GZIPInputStream(new ByteArrayInputStream(compressedBytes))) {
      try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
        inputStream.transferTo(outputStream);
        return outputStream.toByteArray();
      }
    }

}

Answer 3

Look at those samples, and wherever they're using FileOutputStream, use ByteArrayOutputStream instead. Wherever they're using FileInputStream, use ByteArrayInputStream instead. The rest should be simple.

Answer 4

Why don't you create your own class that extends OutputStream or , whatever is the archive writing to ?

Answer 5

If you want to write to a ByteBuffer you can do this.

private static void uncompress(final byte[] input, final ByteBuffer output) throws IOException
    {
        final GZIPInputStream inputGzipStream = new GZIPInputStream(new ByteArrayInputStream(input));
        Channels.newChannel(inputGzipStream).read(output);
    }