Class DeflaterOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

java.util.zip.DeflaterOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

Direct Known Subclasses:

GZIPOutputStream, ZipOutputStream

public class DeflaterOutputStream
extends FilterOutputStream

This class implements an output stream filter for compressing data in the "deflate" compression format. It is also used as the basis for other types of compression filters, such as GZIPOutputStream.

Unless otherwise noted, passing a null argument to a constructor or method in this class will cause a NullPointerException to be thrown.

Compressor Usage

A DeflaterOutputStream created without specifying a compressor will create a compressor at construction time, and close the compressor when the output stream is closed.

If a compressor is specified when creating a DeflaterOutputStream, it is the responsibility of the caller to close the compressor after closing the output stream.

API Note:

The close() method should be called to release resources used by this stream, either directly, or with the try-with-resources statement.

Since:

1.1

See Also:

• Deflater

Field Summary

Fields

Modifier and Type	Field	Description
protected byte[]	buf	Output buffer for writing compressed data.
protected Deflater	def	Compressor for this stream.

Fields declared in class FilterOutputStream

out

Constructor Summary

Constructors

Constructor	Description
DeflaterOutputStream(OutputStream out)	Creates a new output stream and compressor with the default compression level and a default buffer size.
DeflaterOutputStream(OutputStream out, boolean syncFlush)	Creates a new output stream and compressor with the default compression level, a default buffer size and the specified flush mode.
DeflaterOutputStream(OutputStream out, Deflater def)	Creates a new output stream with the specified compressor and a default buffer size.
DeflaterOutputStream(OutputStream out, Deflater def, boolean syncFlush)	Creates a new output stream with the specified compressor, flush mode and a default buffer size.
DeflaterOutputStream(OutputStream out, Deflater def, int size)	Creates a new output stream with the specified compressor and buffer size.
DeflaterOutputStream(OutputStream out, Deflater def, int size, boolean syncFlush)	Creates a new output stream with the specified compressor, buffer size and flush mode.

Method Summary

Modifier and Type	Method	Description
void	close()	Writes remaining compressed data to the output stream and closes the underlying stream.
protected 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.

Methods declared in class FilterOutputStream

write

Methods declared in class OutputStream

nullOutputStream

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

def

protected Deflater def

Compressor for this stream.

buf

protected byte[] buf

Output buffer for writing compressed data.

Constructor Details

DeflaterOutputStream

public DeflaterOutputStream(OutputStream out,
 Deflater def,
 int size,
 boolean syncFlush)

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

Closing this output stream will not close the given compressor.

Parameters:

out - the output stream

def - the compressor ("deflater")

size - the output buffer size

syncFlush - if true the 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:

IllegalArgumentException - if size <= 0

Since:

1.7

DeflaterOutputStream

public DeflaterOutputStream(OutputStream out,
 Deflater def,
 int size)

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

The new output stream instance is created as if by invoking the 4-argument constructor DeflaterOutputStream(out, def, size, false).

Closing this output stream will not close the given compressor.

Parameters:

out - the output stream

def - the compressor ("deflater")

size - the output buffer size

Throws:

IllegalArgumentException - if size <= 0

DeflaterOutputStream

public DeflaterOutputStream(OutputStream out,
 Deflater def,
 boolean syncFlush)

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

Closing this output stream will not close the given compressor.

Parameters:

out - the output stream

def - the compressor ("deflater")

syncFlush - if true the 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

Since:

1.7

DeflaterOutputStream

public DeflaterOutputStream(OutputStream out,
 Deflater def)

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

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

Closing this output stream will not close the given compressor.

Parameters:

out - the output stream

def - the compressor ("deflater")

DeflaterOutputStream

public DeflaterOutputStream(OutputStream out,
 boolean syncFlush)

Creates a new output stream and compressor with the default compression level, a default buffer size and the specified flush mode.

The compressor will be closed when this output stream is closed.

Parameters:

out - the output stream

syncFlush - if true the 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

Since:

1.7

DeflaterOutputStream

public DeflaterOutputStream(OutputStream out)

Creates a new output stream and compressor with the default compression level and a default buffer size.

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

The compressor will be closed when this output stream is closed.

Parameters:

out - the output stream

Method Details

write

public void write(int b)
           throws IOException

Writes a byte to the compressed output stream. This method will block until the byte can be written.

Overrides:

write in class FilterOutputStream

Parameters:

b - the byte to be written

Throws:

IOException - if an I/O error has occurred

write

public void write(byte[] b,
 int off,
 int len)
           throws IOException

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

Overrides:

write in class FilterOutputStream

Parameters:

b - 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

See Also:

• FilterOutputStream.write(int)

finish

public void finish()
            throws IOException

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

close

public void close()
           throws IOException

Writes remaining compressed data to the output stream and closes the underlying stream.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class FilterOutputStream

Throws:

IOException - if an I/O error has occurred

See Also:

• FilterOutputStream.flush()
• FilterOutputStream.out

deflate

protected void deflate()
                throws IOException

Writes next block of compressed data to the output stream.

Throws:

IOException - if an I/O error has occurred

flush

public void flush()
           throws IOException

Flushes the compressed output stream. If syncFlush is true when this compressed output stream is constructed, this method first flushes the underlying compressor with the flush mode Deflater.SYNC_FLUSH to force all pending data to be flushed out to the output stream and then flushes the output stream. Otherwise this method only flushes the output stream without flushing the compressor.

Specified by:

flush in interface Flushable

Overrides:

flush in class FilterOutputStream

Throws:

IOException - if an I/O error has occurred

Since:

1.7

See Also:

• FilterOutputStream.out