java.lang.Objectjava.util.zip.Deflater
public class Deflater
This class provides support for general purpose compression 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 .
try { // 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");
} catch(java.io.UnsupportedEncodingException ex) { // handle } catch (java.util.zip.DataFormatException ex) { // handle }
Field Summary | |
---|---|
static int |
BEST_COMPRESSION
Compression level for best compression. |
static int |
BEST_SPEED
Compression level for fastest compression. |
static int |
DEFAULT_COMPRESSION
Default compression level. |
static int |
DEFAULT_STRATEGY
Default compression strategy. |
static int |
DEFLATED
Compression method for the deflate algorithm (the only one currently supported). |
static int |
FILTERED
Compression strategy best used for data consisting mostly of small values with a somewhat random distribution. |
static int |
HUFFMAN_ONLY
Compression strategy for Huffman coding only. |
static int |
NO_COMPRESSION
Compression level for no compression. |
Constructor Summary | |
---|---|
Deflater
() Creates a new compressor with the default compression level. |
|
Deflater
(int level) Creates a new compressor using the specified compression level. |
|
Deflater
(int level, boolean nowrap) Creates a new compressor using the specified compression level. |
Method Summary | |
---|---|
int |
deflate
(byte[] b) Fills specified buffer with compressed data. |
int |
deflate
(byte[] b, int off, int len) Fills specified buffer with compressed data. |
void |
end
() Closes the compressor and discards any unprocessed input. |
protected void |
finalize
() Closes the compressor when garbage is collected. |
void |
finish
() When called, indicates that compression should end with the current contents of the input buffer. |
boolean |
finished
() Returns true if the end of the compressed data output stream has been reached. |
int |
getAdler
() Returns the ADLER-32 value of the uncompressed data. |
long |
getBytesRead
() Returns the total number of uncompressed bytes input so far. |
long |
getBytesWritten
() Returns the total number of compressed bytes output so far. |
int |
getTotalIn
() Returns the total number of uncompressed bytes input so far. |
int |
getTotalOut
() Returns the total number of compressed bytes output so far. |
boolean |
needsInput
() Returns true if the input data buffer is empty and setInput() should be called in order to provide more input. |
void |
reset
() Resets deflater so that a new set of input data can be processed. |
void |
setDictionary
(byte[] b) Sets preset dictionary for compression. |
void |
setDictionary
(byte[] b, int off, int len) Sets preset dictionary for compression. |
void |
setInput
(byte[] b) Sets input data for compression. |
void |
setInput
(byte[] b, int off, int len) Sets input data for compression. |
void |
setLevel
(int level) Sets the current compression level to the specified value. |
void |
setStrategy
(int strategy) Sets the compression strategy to the specified value. |
Methods inherited from class java.lang. Object |
---|
clone , equals , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
Field Detail |
---|
public static final int DEFLATED
public static final int NO_COMPRESSION
public static final int BEST_SPEED
public static final int BEST_COMPRESSION
public static final int DEFAULT_COMPRESSION
public static final int FILTERED
public static final int HUFFMAN_ONLY
public static final int DEFAULT_STRATEGY
Constructor Detail |
---|
public Deflater(int level, boolean nowrap)
public Deflater(int level)
public Deflater()
Method Detail |
---|
public void setInput(byte[] b, int off, int len)
public void setInput(byte[] b)
public void setDictionary(byte[] b, int off, int len)
public void setDictionary(byte[] b)
public void setStrategy(int strategy)
public void setLevel(int level)
public boolean needsInput()
public void finish()
public boolean finished()
public int deflate(byte[] b, int off, int len)
public int deflate(byte[] b)
public int getAdler()
public int getTotalIn()
Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesRead() method is now the preferred means of obtaining this information.
public long getBytesRead()
public int getTotalOut()
Since the number of bytes may be greater than Integer.MAX_VALUE, the getBytesWritten() method is now the preferred means of obtaining this information.
public long getBytesWritten()
public void reset()
public void end()
protected void finalize()