ZipInputStream

AI-generated Key Takeaways

• ZipInputStream provides functionality to read and extract data from ZIP archive files, supporting both compressed and uncompressed entries.

• It offers methods for navigating through ZIP entries (getNextEntry, closeEntry), reading entry data (read), and managing the stream (close, available, skip).

• ZipInputStream utilizes a specified or default character set for decoding entry names, while adhering to the language encoding bit in the entry's general purpose bit flag if present.

• Several constants represent essential ZIP file structure elements like header signatures and sizes (CENSIG, LOCSIG, EXTSIG, CENHDR, LOCHDR, EXTHDR).

• Potential exceptions include IOException, ZipException, NullPointerException, IndexOutOfBoundsException, and IllegalArgumentException during operations.

public class ZipInputStream extends InflaterInputStream

Known Direct Subclasses JarInputStream JarInputStream The JarInputStream class is used to read the contents of a JAR file from any input stream.

This class implements an input stream filter for reading files in the ZIP file format. Includes support for both compressed and uncompressed entries.

Constant Summary

int	CENATT
int	CENATX
int	CENCOM
int	CENCRC
int	CENDSK
int	CENEXT
int	CENFLG
int	CENHDR
int	CENHOW
int	CENLEN
int	CENNAM
int	CENOFF
long	CENSIG
int	CENSIZ
int	CENTIM
int	CENVEM
int	CENVER
int	ENDCOM
int	ENDHDR
int	ENDOFF
long	ENDSIG
int	ENDSIZ
int	ENDSUB
int	ENDTOT
int	EXTCRC
int	EXTHDR
int	EXTLEN
long	EXTSIG
int	EXTSIZ
int	LOCCRC
int	LOCEXT
int	LOCFLG
int	LOCHDR
int	LOCHOW
int	LOCLEN
int	LOCNAM
long	LOCSIG
int	LOCSIZ
int	LOCTIM
int	LOCVER

Inherited Field Summary

From class java.util.zip.InflaterInputStream

protected byte[]	buf	Input buffer for decompression.
protected boolean	closed	This field is deprecated. This field will be removed from a future version of Android and should not be used. Subclasses that access this field need to be modified to keep track of their own closed state by overriding close().
protected Inflater	inf	Decompressor for this stream.
protected int	len	Length of input buffer.

From class java.io.FilterInputStream

protected InputStream

in

The input stream to be filtered.

Public Constructor Summary

	ZipInputStream(InputStream in) Creates a new ZIP input stream.
	ZipInputStream(InputStream in, Charset charset) Creates a new ZIP input stream.

Public Method Summary

int	available() Returns 0 after EOF has reached for the current entry data, otherwise always return 1.
void	close() Closes this input stream and releases any system resources associated with the stream.
void	closeEntry() Closes the current ZIP entry and positions the stream for reading the next entry.
ZipEntry	getNextEntry() Reads the next ZIP file entry and positions the stream at the beginning of the entry data.
int	read(byte[] b, int off, int len) Reads from the current ZIP entry into an array of bytes.
long	skip(long n) Skips specified number of bytes in the current ZIP entry.

Protected Method Summary

ZipEntry

createZipEntry(String name) Creates a new ZipEntry object for the specified entry name.

Inherited Method Summary

From class java.util.zip.InflaterInputStream

int	available() Returns 0 after EOF has been reached, otherwise always return 1.
void	close() Closes this input stream and releases any system resources associated with the stream.
void	fill() Fills input buffer with more data to decompress.
synchronized void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the mark and reset methods.
int	read() Reads a byte of uncompressed data.
int	read(byte[] b, int off, int len) Reads uncompressed data into an array of bytes.
synchronized void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n) Skips specified number of bytes of uncompressed data.

From class java.io.FilterInputStream

int	available() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
void	close() Closes this input stream and releases any system resources associated with the stream.
synchronized void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the mark and reset methods.
int	read() Reads the next byte of data from this input stream.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from this input stream into an array of bytes.
int	read(byte[] b) Reads up to byte.length bytes of data from this input stream into an array of bytes.
synchronized void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n) Skips over and discards n bytes of data from the input stream.

From class java.io.InputStream

int	available() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.
void	close() Closes this input stream and releases any system resources associated with the stream.
synchronized void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the mark and reset methods.
abstract int	read() Reads the next byte of data from the input stream.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
int	read(byte[] b) Reads some number of bytes from the input stream and stores them into the buffer array b.
synchronized void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n) Skips over and discards n bytes of data from this input stream.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.io.Closeable

abstract void

close() Closes this stream and releases any system resources associated with it.

From interface java.lang.AutoCloseable

abstract void

close() Closes this resource, relinquishing any underlying resources.

Constants

public static final int CENATT

Constant Value: 36

public static final int CENATX

Constant Value: 38

public static final int CENCOM

Constant Value: 32

public static final int CENCRC

Constant Value: 16

public static final int CENDSK

Constant Value: 34

public static final int CENEXT

Constant Value: 30

public static final int CENFLG

Constant Value: 8

public static final int CENHDR

Constant Value: 46

public static final int CENHOW

Constant Value: 10

public static final int CENLEN

Constant Value: 24

public static final int CENNAM

Constant Value: 28

public static final int CENOFF

Constant Value: 42

public static final long CENSIG

Constant Value: 33639248

public static final int CENSIZ

Constant Value: 20

public static final int CENTIM

Constant Value: 12

public static final int CENVEM

Constant Value: 4

public static final int CENVER

Constant Value: 6

public static final int ENDCOM

Constant Value: 20

public static final int ENDHDR

Constant Value: 22

public static final int ENDOFF

Constant Value: 16

public static final long ENDSIG

Constant Value: 101010256

public static final int ENDSIZ

Constant Value: 12

public static final int ENDSUB

Constant Value: 8

public static final int ENDTOT

Constant Value: 10

public static final int EXTCRC

Constant Value: 4

public static final int EXTHDR

Constant Value: 16

public static final int EXTLEN

Constant Value: 12

public static final long EXTSIG

Constant Value: 134695760

public static final int EXTSIZ

Constant Value: 8

public static final int LOCCRC

Constant Value: 14

public static final int LOCEXT

Constant Value: 28

public static final int LOCFLG

Constant Value: 6

public static final int LOCHDR

Constant Value: 30

public static final int LOCHOW

Constant Value: 8

public static final int LOCLEN

Constant Value: 22

public static final int LOCNAM

Constant Value: 26

public static final long LOCSIG

Constant Value: 67324752

public static final int LOCSIZ

Constant Value: 18

public static final int LOCTIM

Constant Value: 10

public static final int LOCVER

Constant Value: 4

Public Constructors

public ZipInputStream (InputStream in)

Creates a new ZIP input stream.

The UTF-8 charset is used to decode the entry names.

Parameters

in	the actual input stream

public ZipInputStream (InputStream in, Charset charset)

Creates a new ZIP input stream.

Parameters

in	the actual input stream
charset	The {@linkplain java.nio.charset.Charset charset} to be used to decode the ZIP entry name (ignored if the language encoding bit of the ZIP entry's general purpose bit flag is set).

Public Methods

public int available ()

Returns 0 after EOF has reached for the current entry data, otherwise always return 1.

Programs should not count on this method to return the actual number of bytes that could be read without blocking.

Returns

• 1 before EOF and 0 after EOF has reached for current entry.

Throws

IOException	if an I/O error occurs.

public void close ()

Closes this input stream and releases any system resources associated with the stream.

Throws

IOException	if an I/O error has occurred

public void closeEntry ()

Closes the current ZIP entry and positions the stream for reading the next entry.

Throws

ZipException	if a ZIP file error has occurred
IOException	if an I/O error has occurred

public ZipEntry getNextEntry ()

Reads the next ZIP file entry and positions the stream at the beginning of the entry data.

Returns

• the next ZIP file entry, or null if there are no more entries

Throws

ZipException	if a ZIP file error has occurred
IOException	if an I/O error has occurred

public int read (byte[] b, int off, int len)

Reads from the current ZIP entry into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned.

Parameters

b	the buffer into which the data is read
off	the start offset in the destination array b
len	the maximum number of bytes read

Returns

• the actual number of bytes read, or -1 if the end of the entry is reached

Throws

NullPointerException	if b is null.
IndexOutOfBoundsException	if off is negative, len is negative, or len is greater than b.length - off
ZipException	if a ZIP file error has occurred
IOException	if an I/O error has occurred

public long skip (long n)

Skips specified number of bytes in the current ZIP entry.

Parameters

n	the number of bytes to skip

Returns

• the actual number of bytes skipped

Throws

ZipException	if a ZIP file error has occurred
IOException	if an I/O error has occurred
IllegalArgumentException	if n < 0

Protected Methods

protected ZipEntry createZipEntry (String name)

Creates a new ZipEntry object for the specified entry name.

Parameters

name	the ZIP file entry name

Returns

• the ZipEntry just created