JavaTM 2 Platform Std. Ed. v1.5.0
java.util.zip
Class Inflater
java.lang.Object
java.util.zip.Inflater
public class Inflater - extends Object
This class provides support for general purpose decompression using the
popular ZLIB compression library. The ZLIB compression library was
initially developed as part of the PNG graphics standard and is not
protected by patents. It is fully described in the specifications at
the java.util.zip
package description.
The following code fragment demonstrates a trivial compression
and decompression of a string using Deflater and
Inflater.
// Encode a String into bytes
String inputString = "blahblahblah??";
byte[] input = inputString.getBytes("UTF-8");
// Compress the bytes
byte[] output = new byte[100];
Deflater compresser = new Deflater();
compresser.setInput(input);
compresser.finish();
int compressedDataLength = compresser.deflate(output);
// Decompress the bytes
Inflater decompresser = new Inflater();
decompresser.setInput(output, 0, compressedDataLength);
byte[] result = new byte[100];
int resultLength = decompresser.inflate(result);
decompresser.end();
// Decode the bytes into a String
String outputString = new String(result, 0, resultLength, "UTF-8");
- See Also:
Deflater
Constructor Summary |
Inflater()
Creates a new decompressor. |
Inflater(boolean nowrap)
Creates a new decompressor. |
Method Summary |
void |
end()
Closes the decompressor and discards any unprocessed input. |
protected void |
finalize()
Closes the decompressor when garbage is collected. |
boolean |
finished()
Returns true if the end of the compressed data stream has been
reached. |
int |
getAdler()
Returns the ADLER-32 value of the uncompressed data. |
long |
getBytesRead()
Returns the total number of compressed bytes input so far. |
long |
getBytesWritten()
Returns the total number of uncompressed bytes output so far. |
int |
getRemaining()
Returns the total number of bytes remaining in the input buffer. |
int |
getTotalIn()
Returns the total number of compressed bytes input so far. |
int |
getTotalOut()
Returns the total number of uncompressed bytes output so far. |
int |
inflate(byte[] b)
Uncompresses bytes into specified buffer. |
int |
inflate(byte[] b,
int off,
int len)
Uncompresses bytes into specified buffer. |
boolean |
needsDictionary()
Returns true if a preset dictionary is needed for decompression. |
boolean |
needsInput()
Returns true if no data remains in the input buffer. |
void |
reset()
Resets inflater so that a new set of input data can be processed. |
void |
setDictionary(byte[] b)
Sets the preset dictionary to the given array of bytes. |
void |
setDictionary(byte[] b,
int off,
int len)
Sets the preset dictionary to the given array of bytes. |
void |
setInput(byte[] b)
Sets input data for decompression. |
void |
setInput(byte[] b,
int off,
int len)
Sets input data for decompression. |
Inflater
public Inflater(boolean nowrap)
- Creates a new decompressor. If the parameter 'nowrap' is true then
the ZLIB header and checksum fields will not be used. This provides
compatibility with the compression format used by both GZIP and PKZIP.
Note: When using the 'nowrap' option it is also necessary to provide
an extra "dummy" byte as input. This is required by the ZLIB native
library in order to support certain optimizations.
- Parameters:
nowrap - if true then support GZIP compatible compression
Inflater
public Inflater()
- Creates a new decompressor.
setInput
public void setInput(byte[] b,
int off,
int len)
- Sets input data for decompression. Should be called whenever
needsInput() returns true indicating that more input data is
required.
- Parameters:
b - the input data bytesoff - the start offset of the input datalen - the length of the input data- See Also:
needsInput()
setInput
public void setInput(byte[] b)
- Sets input data for decompression. Should be called whenever
needsInput() returns true indicating that more input data is
required.
- Parameters:
b - the input data bytes- See Also:
needsInput()
setDictionary
public void setDictionary(byte[] b,
int off,
int len)
- Sets the preset dictionary to the given array of bytes. Should be
called when inflate() returns 0 and needsDictionary() returns true
indicating that a preset dictionary is required. The method getAdler()
can be used to get the Adler-32 value of the dictionary needed.
- Parameters:
b - the dictionary data bytesoff - the start offset of the datalen - the length of the data- See Also:
needsDictionary() ,
getAdler()
setDictionary
public void setDictionary(byte[] b)
- Sets the preset dictionary to the given array of bytes. Should be
called when inflate() returns 0 and needsDictionary() returns true
indicating that a preset dictionary is required. The method getAdler()
can be used to get the Adler-32 value of the dictionary needed.
- Parameters:
b - the dictionary data bytes- See Also:
needsDictionary() ,
getAdler()
getRemaining
public int getRemaining()
- Returns the total number of bytes remaining in the input buffer.
This can be used to find out what bytes still remain in the input
buffer after decompression has finished.
- Returns:
- the total number of bytes remaining in the input buffer
needsInput
public boolean needsInput()
- Returns true if no data remains in the input buffer. This can
be used to determine if #setInput should be called in order
to provide more input.
- Returns:
- true if no data remains in the input buffer
needsDictionary
public boolean needsDictionary()
- Returns true if a preset dictionary is needed for decompression.
- Returns:
- true if a preset dictionary is needed for decompression
- See Also:
setDictionary(byte[], int, int)
finished
public boolean finished()
- Returns true if the end of the compressed data stream has been
reached.
- Returns:
- true if the end of the compressed data stream has been
reached
inflate
public int inflate(byte[] b,
int off,
int len)
throws DataFormatException
- Uncompresses bytes into specified buffer. Returns actual number
of bytes uncompressed. A return value of 0 indicates that
needsInput() or needsDictionary() should be called in order to
determine if more input data or a preset dictionary is required.
In the later case, getAdler() can be used to get the Adler-32
value of the dictionary required.
- Parameters:
b - the buffer for the uncompressed dataoff - the start offset of the datalen - the maximum number of uncompressed bytes
- Returns:
- the actual number of uncompressed bytes
- Throws:
DataFormatException - if the compressed data format is invalid- See Also:
needsInput() ,
needsDictionary()
inflate
public int inflate(byte[] b)
throws DataFormatException
- Uncompresses bytes into specified buffer. Returns actual number
of bytes uncompressed. A return value of 0 indicates that
needsInput() or needsDictionary() should be called in order to
determine if more input data or a preset dictionary is required.
In the later case, getAdler() can be used to get the Adler-32
value of the dictionary required.
- Parameters:
b - the buffer for the uncompressed data
- Returns:
- the actual number of uncompressed bytes
- Throws:
DataFormatException - if the compressed data format is invalid- See Also:
needsInput() ,
needsDictionary()
getAdler
public int getAdler()
- Returns the ADLER-32 value of the uncompressed data.
- Returns:
- the ADLER-32 value of the uncompressed data
getTotalIn
public int getTotalIn()
- Returns the total number of compressed bytes input so far.
Since the number of bytes may be greater than
Integer.MAX_VALUE, the getBytesRead() method is now
the preferred means of obtaining this information.
- Returns:
- the total number of compressed bytes input so far
getBytesRead
public long getBytesRead()
- Returns the total number of compressed bytes input so far.
- Returns:
- the total (non-negative) number of compressed bytes input so far
getTotalOut
public int getTotalOut()
- Returns the total number of uncompressed bytes output so far.
Since the number of bytes may be greater than
Integer.MAX_VALUE, the getBytesWritten() method is now
the preferred means of obtaining this information.
- Returns:
- the total number of uncompressed bytes output so far
getBytesWritten
public long getBytesWritten()
- Returns the total number of uncompressed bytes output so far.
- Returns:
- the total (non-negative) number of uncompressed bytes output so far
reset
public void reset()
- Resets inflater so that a new set of input data can be processed.
end
public void end()
- Closes the decompressor and discards any unprocessed input.
This method should be called when the decompressor is no longer
being used, but will also be called automatically by the finalize()
method. Once this method is called, the behavior of the Inflater
object is undefined.
finalize
protected void finalize()
- Closes the decompressor when garbage is collected.
- Overrides:
finalize in class Object
Copyright 2003 Sun Microsystems, Inc. All rights reserved
|