gzip archive with multiple files inside

问题:

I need to create a gzip archive with multiple files inside, how can I do this without ArchiveEntry available for java.util.zip.GZIPOutputStream class?

回答1:

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.

回答2:

GZip compresses a stream. Typically, when people use GZip with multiple files, they also use tar to munch them together

You can find a java tar libarary here: http://www.trustice.com/java/tar/

Or you could use Zip instead of GZip