Java IO.pdf - Nguyen Dang Binh

% java FancyZipLister temp.zip
test.txt was deflated at Wed Jun 11 15:57:32 EDT 1997
from 187 bytes to 98 bytes, a savings of 52.406417112299465%
Its CRC is 1981281836
ticktock.txt was deflated at Wed Jun 11 10:42:02 EDT 1997
from 1480 bytes to 405 bytes, a savings of 27.364864864864863%
Its CRC is 4103395328
Java I/O
There are also six corresponding set methods, which are used to attach information to each
entry you store in a zip archive. However, most of the time it's enough to let the ZipEntry
class calculate these for you:
public void setTime(long time)
public void setSize(long size)
public void setCrc(long crc)
public void setMethod(int method)
public void setExtra(byte[] extra)
public void setComment(String comment)
Finally, there's the toString() method, which was implicitly used in the ZipLister program
to print the name of each entry:
public String toString()
Java 2 adds hashCode() and clone() methods:
public int hashCode() // Java 2
public Object clone() // Java 2
In Java 1.1, ZipEntry simply inherits these methods from java.lang.Object. However,
ZipEntry only implements the Cloneable interface in Java 2, not in Java 1.1.
9.3.2 The ZipOutputStream Class
The java.util.zip.ZipOutputStream class subclasses DeflaterOutputStream and writes
compressed data in the zip format. ZipOutputStream implements the nonpublic
java.util.zip.ZipConstants interface.
public class ZipOutputStream extends DeflaterOutputStream
implements ZipConstants
Java supports two zip formats, uncompressed and compressed. These are slightly less
obviously known as stored and deflated. They correspond to the mnemonic constants
ZipOutputStream.STORED and ZipOutputStream.DEFLATED:
public static final int STORED = ZipEntry.STORED;
public static final int DEFLATED = ZipEntry.DEFLATED;
Deflated files are compressed by a Deflater object using the deflation method. Stored files
are copied byte for byte into the archive without any compression. This is the right format for
files that are already compressed but still need to go into the archive, like a GIF image or an
MPEG movie.
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