GZIPOutputStream

AI-generated Key Takeaways

• GZIPOutputStream is a stream filter in Java used for writing compressed data in the GZIP file format.

• It provides constructors to create instances with specified buffer sizes and flush modes.

• The write method enables writing compressed data to the output stream.

• The finish method completes the compression process without closing the stream.

• CRC-32 checksum is used to ensure the integrity of the uncompressed data.

public class GZIPOutputStream extends DeflaterOutputStream

This class implements a stream filter for writing compressed data in the GZIP file format.

Field Summary

protected CRC32

crc

CRC-32 of uncompressed data.

Inherited Field Summary

From class java.util.zip.DeflaterOutputStream

protected byte[]	buf	Output buffer for writing compressed data.
protected Deflater	def	Compressor for this stream.

From class java.io.FilterOutputStream

protected OutputStream

out

The underlying output stream to be filtered.

Public Constructor Summary

	GZIPOutputStream(OutputStream out, int size) Creates a new output stream with the specified buffer size.
	GZIPOutputStream(OutputStream out, int size, boolean syncFlush) Creates a new output stream with the specified buffer size and flush mode.
	GZIPOutputStream(OutputStream out) Creates a new output stream with a default buffer size.
	GZIPOutputStream(OutputStream out, boolean syncFlush) Creates a new output stream with a default buffer size and the specified flush mode.

Public Method Summary

void	finish() Finishes writing compressed data to the output stream without closing the underlying stream.
synchronized void	write(byte[] buf, int off, int len) Writes array of bytes to the compressed output stream.

Inherited Method Summary

From class java.util.zip.DeflaterOutputStream

void	close() Writes remaining compressed data to the output stream and closes the underlying stream.
void	deflate() Writes next block of compressed data to the output stream.
void	finish() Finishes writing compressed data to the output stream without closing the underlying stream.
void	flush() Flushes the compressed output stream.
void	write(byte[] b, int off, int len) Writes an array of bytes to the compressed output stream.
void	write(int b) Writes a byte to the compressed output stream.

From class java.io.FilterOutputStream

void	close() Closes this output stream and releases any system resources associated with the stream.
void	flush() Flushes this output stream and forces any buffered output bytes to be written out to the stream.
void	write(byte[] b) Writes b.length bytes to this output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
void	write(int b) Writes the specified byte to this output stream.

From class java.io.OutputStream

void	close() Closes this output stream and releases any system resources associated with this stream.
void	flush() Flushes this output stream and forces any buffered output bytes to be written out.
void	write(byte[] b) Writes b.length bytes from the specified byte array to this output stream.
void	write(byte[] b, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
abstract void	write(int b) Writes the specified byte to this output 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.io.Flushable

abstract void

flush() Flushes this stream by writing any buffered output to the underlying stream.

From interface java.lang.AutoCloseable

abstract void

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

Fields

protected CRC32 crc

CRC-32 of uncompressed data.

Public Constructors

public GZIPOutputStream (OutputStream out, int size)

Creates a new output stream with the specified buffer size.

The new output stream instance is created as if by invoking the 3-argument constructor GZIPOutputStream(out, size, false).

Parameters

out	the output stream
size	the output buffer size

Throws

IOException	If an I/O error has occurred.
IllegalArgumentException	if size <= 0

public GZIPOutputStream (OutputStream out, int size, boolean syncFlush)

Creates a new output stream with the specified buffer size and flush mode.

Parameters

out	the output stream
size	the output buffer size
syncFlush	if true invocation of the inherited flush() method of this instance flushes the compressor with flush mode Deflater.SYNC_FLUSH before flushing the output stream, otherwise only flushes the output stream

Throws

IOException	If an I/O error has occurred.
IllegalArgumentException	if size <= 0

public GZIPOutputStream (OutputStream out)

Creates a new output stream with a default buffer size.

The new output stream instance is created as if by invoking the 2-argument constructor GZIPOutputStream(out, false).

Parameters

out	the output stream

Throws

IOException	If an I/O error has occurred.

public GZIPOutputStream (OutputStream out, boolean syncFlush)

Creates a new output stream with a default buffer size and the specified flush mode.

Parameters

out	the output stream
syncFlush	if true invocation of the inherited flush() method of this instance flushes the compressor with flush mode Deflater.SYNC_FLUSH before flushing the output stream, otherwise only flushes the output stream

Throws

IOException	If an I/O error has occurred.

Public Methods

public void finish ()

Finishes writing compressed data to the output stream without closing the underlying stream. Use this method when applying multiple filters in succession to the same output stream.

Throws

IOException	if an I/O error has occurred

public synchronized void write (byte[] buf, int off, int len)

Writes array of bytes to the compressed output stream. This method will block until all the bytes are written.

Parameters

buf	the data to be written
off	the start offset of the data
len	the length of the data

Throws

IOException	If an I/O error has occurred.