org.codehaus.plexus.archiver.zip

Class ZipFile


public class ZipFile
extends java.lang.Object

Replacement for java.util.ZipFile.

This class adds support for file name encodings other than UTF-8 (which is required to work on ZIP files created by native zip tools and is able to skip a preamble like the one found in self extracting archives. Furthermore it returns instances of org.apache.tools.zip.ZipEntry instead of java.util.zip.ZipEntry.

It doesn't extend java.util.zip.ZipFile as it would have to reimplement all methods anyway. Like java.util.ZipFile, it uses RandomAccessFile under the covers and supports compressed and uncompressed entries.

The method signatures mimic the ones of java.util.zip.ZipFile, with a couple of exceptions:

Version:
$Revision: 2436 $ $Date: 2005-09-01 13:20:41 -0400 (Thu, 01 Sep 2005) $ from org.apache.ant.tools.zip.ZipFile v1.13

Nested Class Summary

private class
ZipFile.BoundedInputStream
InputStream that delegates requests to the underlying RandomAccessFile, making sure that only bytes from a certain range can be read.

Field Summary

private static int
CFD_LOCATOR_OFFSET
private static int
CFH_LEN
private static long
LFH_OFFSET_FOR_FILENAME_LENGTH
Number of bytes in local file header up to the "length of filename" entry.
private static int
MIN_EOCD_SIZE
private RandomAccessFile
archive
The actual data source.
private Hashtable
dataOffsets
Maps ZipEntrys to Longs, recording the offsets of the actual file data.
private String
encoding
The encoding to use for filenames and the file comment.
private Hashtable
entries
Maps ZipEntrys to Longs, recording the offsets of the local file headers.
private Hashtable
nameMap
Maps String to ZipEntrys, name -> actual entry.

Constructor Summary

ZipFile(File f)
Opens the given file for reading, assuming the platform's native encoding for file names.
ZipFile(File f, String encoding)
Opens the given file for reading, assuming the specified encoding for file names.
ZipFile(String name)
Opens the given file for reading, assuming the platform's native encoding for file names.
ZipFile(String name, String encoding)
Opens the given file for reading, assuming the specified encoding for file names.

Method Summary

void
close()
Closes the archive.
protected static Date
fromDosTime(ZipLong l)
Convert a DOS date/time field to a Date object.
String
getEncoding()
The encoding to use for filenames and the file comment.
Enumeration
getEntries()
Returns all entries.
ZipEntry
getEntry(String name)
Returns a named entry - or null if no entry by that name exists.
InputStream
getInputStream(ZipEntry ze)
Returns an InputStream for reading the contents of the given entry.
protected String
getString(byte[] bytes)
Retrieve a String from the given bytes using the encoding set for this ZipFile.
private void
populateFromCentralDirectory()
Reads the central directory of the given archive and populates the internal tables with ZipEntry instances.
private void
positionAtCentralDirectory()
Searches for the "End of central dir record", parses it and positions the stream at the first central directory record.
private void
resolveLocalFileHeaderData()
Walks through all recorded entries and adds the data available from the local file header.

Field Details

CFD_LOCATOR_OFFSET

private static final int CFD_LOCATOR_OFFSET
Field Value:
16

CFH_LEN

private static final int CFH_LEN
Field Value:
42

LFH_OFFSET_FOR_FILENAME_LENGTH

private static final long LFH_OFFSET_FOR_FILENAME_LENGTH
Number of bytes in local file header up to the "length of filename" entry.
Field Value:
26L

MIN_EOCD_SIZE

private static final int MIN_EOCD_SIZE
Field Value:
22

archive

private RandomAccessFile archive
The actual data source.

dataOffsets

private Hashtable dataOffsets
Maps ZipEntrys to Longs, recording the offsets of the actual file data.

encoding

private String encoding

entries

private Hashtable entries
Maps ZipEntrys to Longs, recording the offsets of the local file headers.

nameMap

private Hashtable nameMap
Maps String to ZipEntrys, name -> actual entry.

Constructor Details

ZipFile

public ZipFile(File f)
            throws IOException
Opens the given file for reading, assuming the platform's native encoding for file names.
Parameters:
f - the archive.

ZipFile

public ZipFile(File f,
               String encoding)
            throws IOException
Opens the given file for reading, assuming the specified encoding for file names.
Parameters:
f - the archive.
encoding - the encoding to use for file names

ZipFile

public ZipFile(String name)
            throws IOException
Opens the given file for reading, assuming the platform's native encoding for file names.
Parameters:
name - name of the archive.

ZipFile

public ZipFile(String name,
               String encoding)
            throws IOException
Opens the given file for reading, assuming the specified encoding for file names.
Parameters:
name - name of the archive.
encoding - the encoding to use for file names

Method Details

close

public void close()
            throws IOException
Closes the archive.

fromDosTime

protected static Date fromDosTime(ZipLong l)
Convert a DOS date/time field to a Date object.
Parameters:
l - contains the stored DOS time.
Returns:
a Date instance corresponding to the given time.

getEncoding

public String getEncoding()
The encoding to use for filenames and the file comment.
Returns:
null if using the platform's default character encoding.

getEntries

public Enumeration getEntries()
Returns all entries.

getEntry

public ZipEntry getEntry(String name)
Returns a named entry - or null if no entry by that name exists.
Parameters:
name - name of the entry.
Returns:
the ZipEntry corresponding to the given name - or null if not present.

getInputStream

public InputStream getInputStream(ZipEntry ze)
            throws IOException,
                   ZipException
Returns an InputStream for reading the contents of the given entry.
Parameters:
ze - the entry to get the stream for.
Returns:
a stream to read the entry from.

getString

protected String getString(byte[] bytes)
            throws ZipException
Retrieve a String from the given bytes using the encoding set for this ZipFile.
Parameters:
bytes - the byte array to transform
Returns:
String obtained by using the given encoding

populateFromCentralDirectory

private void populateFromCentralDirectory()
            throws IOException
Reads the central directory of the given archive and populates the internal tables with ZipEntry instances.

The ZipEntrys will know all data that can be obtained from the central directory alone, but not the data that requires the local file header or additional data to be read.


positionAtCentralDirectory

private void positionAtCentralDirectory()
            throws IOException
Searches for the "End of central dir record", parses it and positions the stream at the first central directory record.

resolveLocalFileHeaderData

private void resolveLocalFileHeaderData()
            throws IOException
Walks through all recorded entries and adds the data available from the local file header.

Also records the offsets for the data to read from the entries.