net.rim.device.api.compress
Class GZIPOutputStream

java.lang.Object
  java.io.OutputStream
      net.rim.device.api.compress.GZIPOutputStream

public class GZIPOutputStream
extends OutputStream

Output stream for writing a data stream compressed with the GZIP algorithm (RFC 1952).

Sample code

public static byte[] compress( byte[] data )
{
try
{
ByteArrayOutputStream baos = new ByteArrayOutputStream();
GZIPOutputStream gzipStream = new GZIPOutputStream( baos, 6, GZIPOutputStream.MAX_LOG2_WINDOW_LENGTH );
gzipStream.write( data );
gzipStream.close();
}
catch(IOException ioe)
{
return null;
}

return baos.toByteArray();
}

Field Summary
static int	COMPRESSION_BEST
static int	COMPRESSION_NONE
static int	MAX_LOG2_WINDOW_LENGTH
static int	MIN_LOG2_WINDOW_LENGTH

Constructor Summary

GZIPOutputStream(OutputStream outputStream)
Creates a new GZIPOutputStream instance with COMPRESSION_NONE.

GZIPOutputStream(OutputStream outputStream, int compressionValue)
Creates a new GZIPOutputStream instance.

GZIPOutputStream(OutputStream outputStream, int compressionValue, int windowLength)
Creates a new GZIPOutputStream instance.

Method Summary
void	close() Closes this output stream.
void	flush() Flushes this stream, writing out any remaining buffered data.
void	write(byte[] data, int dataOffset, int dataLength) Writes some bytes from byte array to this stream.
void	write(int data) Writes a byte to this stream.

Methods inherited from class java.io.OutputStream

write

Methods inherited from class java.lang.Object

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

Field Detail

MIN_LOG2_WINDOW_LENGTH

public static final int MIN_LOG2_WINDOW_LENGTH

See Also:

Constant Field Values

Since:

BlackBerry API 4.1.0

MAX_LOG2_WINDOW_LENGTH

public static final int MAX_LOG2_WINDOW_LENGTH

See Also:

Constant Field Values

Since:

BlackBerry API 4.1.0

COMPRESSION_NONE

public static final int COMPRESSION_NONE

See Also:

Constant Field Values

Since:

BlackBerry API 4.1.0

COMPRESSION_BEST

public static final int COMPRESSION_BEST

See Also:

Constant Field Values

Since:

BlackBerry API 4.1.0

Constructor Detail

GZIPOutputStream

public GZIPOutputStream(OutputStream outputStream)

Creates a new GZIPOutputStream instance with COMPRESSION_NONE.

Note this constructor provides no compression; this is done to be compatible with prior implementations of this class. Use the alternate constructor which accepts the compression value to achieve compression.

Parameters:

outputStream - Underlying output stream to use.

GZIPOutputStream

public GZIPOutputStream(OutputStream outputStream,
                        int compressionValue)

Creates a new GZIPOutputStream instance.

Parameters:

outputStream - Underlying output stream to use.

compressionValue - 0 to 9 representing compression value; 0 being none; 9 being best.

Since:

BlackBerry API 4.1.0

GZIPOutputStream

public GZIPOutputStream(OutputStream outputStream,
                        int compressionValue,
                        int windowLength)

Creates a new GZIPOutputStream instance.

windowLength can range from 8 to 15. Note: if the value was 10, the window length would be 2^10 = 1024 bytes. This parameter can be used to limit the window length for those decompressors which are not capable of dealing with the maximum window length (2^15 -> 32KB). Note, the actual window length may be smaller.

Parameters:

outputStream - Underlying output stream to use.

compressionValue - 0 to 9 representing compression value; 0 being none; 9 being best.

windowLength - The window length to use.

Since:

BlackBerry API 4.1.0

Method Detail

write

public void write(int data)
           throws IOException

Writes a byte to this stream.

Specified by:

write in class OutputStream

Parameters:

data - the byte to be written

Throws:

IOException - If an I/O error occurs.

write

public void write(byte[] data,
                  int dataOffset,
                  int dataLength)
           throws IOException

Writes some bytes from byte array to this stream.

Invoke this method to compress, and then write, some bytes contained in the input array to this stream.

Overrides:

write in class OutputStream

Parameters:

data - Data to write.

dataOffset - First byte from provided array to compress and write.

dataLength - Number of bytes from provided array to compress and write.

Throws:

IOException - If an I/O error occurs.

flush

public void flush()
           throws IOException

Flushes this stream, writing out any remaining buffered data.

Overrides:

flush in class OutputStream

Throws:

IOException - If an I/O error occurs.

close

public void close()
           throws IOException

Closes this output stream.

Overrides:

close in class OutputStream

Throws:

IOException - If an I/O error occurs.