Java IO.pdf - Nguyen Dang Binh

}
}
}
FileOutputStream fout = new FileOutputStream(
args[i].substring(0, args[i].length()-3));
StreamCopier.copy(gzin, fout);
fout.close();
}
catch (IOException e) {System.err.println(e);}
}
else {
System.err.println(args[i] + " does not appear to be a gzipped
file.");
}
9.2.5 Expanding Output Streams and Compressing Input Streams
Java I/O
You may have noticed that the compression stream classes are not fully symmetrical. You can
expand the data being read from an input stream, and you can compress data being written to
an output stream, but there are no classes that compress data being read from an input stream
or expand data being written to an output stream. Such classes aren't commonly needed. It's
possible that you might want to read compressed data from a file and write uncompressed data
onto the network, but as long as there are an input stream and an output stream, you can
always put the compressor on the output stream or the decompressor on the input stream. In
either case, the compressor and decompressor fall between the two underlying streams, so
how they're chained doesn't really matter. Alternatively, you may have some reason to work
with compressed data in memory; for example, your application might find it more efficient to
store large chunks of text in compressed form. In this case, a byte array output stream chained
to a deflater output stream will do the trick.
9.3 Working with Zip Files
Gzip and deflate are compression formats. Zip is both a compression and an archive format.
This means that a single zip file may contain more than one uncompressed file, along with
information about the names, permissions, creation and modification dates, and other
information about each file in the archive. This makes reading and writing zip archives
somewhat more complex and somewhat less amenable to a stream metaphor than reading and
writing deflated or gzipped files.
The java.util.zip.ZipFile class represents a file in the zip format. Such a file might be
created by zip, PKZip, ZipIt, WinZip, or any of the many other zip programs. The
java.util.zip.ZipEntry class represents a single file stored in such an archive.
public class ZipFile extends Object implements ZipConstants
public class ZipEntry extends Object implements ZipConstants
The java.util.zip.ZipConstants interface that both these classes
implement is a rare nonpublic interface that contains constants useful
for reading and writing zip files. Most of these constants define the
positions in a zip file where particular information, like the compression
method used, is found. You don't need to concern yourself with it.
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