gzip archive with multiple files inside

compression, gzip, java

Solution

According to the Wikipedia entry on `gzip`:

Although its file format also allows for multiple such streams to be concatenated (zipped files are simply decompressed concatenated as if they were originally one file), gzip is normally used to compress just single files.

This is why `GZIPOutputStream` doesn't support `ArchiveEntry`.

Normally, multiple files are archived into one with `tar`, then compressed with `gzip` to produce a `.tar.gz` compressed archive.

You could create a `tar.gz` in this way by using the `Apache Commons Compress` implementation for `tar`:

file_out = new FileOutputStream (new File ("archive.tar.gz"));
buffer_out = new BufferedOutputStream (file_out);
gzip_out = new GzipCompressorOutputStream (buffer_out);
tar_out = new TarArchiveOutputStream (gzip_out);

// .. and then talk to 'tar_out' to write stuff

Here is a more thorough example that compresses entire directories.

Problem

Original source