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\u20AC\u20AC";
+ * 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
+ * }
+ * + * 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. + * + * @param nowrap if true then support GZIP compatible compression + */ + public Inflater(boolean nowrap) { + this.nowrap = nowrap; + reset(); + } + + /** + * Creates a new decompressor. + */ + public Inflater() { + this(false); + } + + /** + * Sets input data for decompression. Should be called whenever + * needsInput() returns true indicating that more input data is + * required. + * @param b the input data bytes + * @param off the start offset of the input data + * @param len the length of the input data + * @see Inflater#needsInput + */ + public void setInput(byte[] b, int off, int len) { + if (b == null) { + throw new NullPointerException(); + } + if (off < 0 || len < 0 || off > b.length - len) { + throw new ArrayIndexOutOfBoundsException(); + } + impl.setInput(b, off, len, false); + } + + /** + * Sets input data for decompression. Should be called whenever + * needsInput() returns true indicating that more input data is + * required. + * @param b the input data bytes + * @see Inflater#needsInput + */ + public void setInput(byte[] b) { + setInput(b, 0, b.length); + } + + /** + * 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. + * @param b the dictionary data bytes + * @param off the start offset of the data + * @param len the length of the data + * @see Inflater#needsDictionary + * @see Inflater#getAdler + */ + public void setDictionary(byte[] b, int off, int len) { + if (b == null) { + throw new NullPointerException(); + } + if (off < 0 || len < 0 || off > b.length - len) { + throw new ArrayIndexOutOfBoundsException(); + } + byte[] arr; + if (off == 0) { + arr = b; + } else { + arr = new byte[len]; + org.apidesign.bck2brwsr.emul.lang.System.arraycopy(b, off, arr, 0, len); + } + impl.setDictionary(arr, 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. + * @param b the dictionary data bytes + * @see Inflater#needsDictionary + * @see Inflater#getAdler + */ + public void setDictionary(byte[] b) { + impl.setDictionary(b, b.length); + } + + /** + * 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. + * @return the total number of bytes remaining in the input buffer + */ + public int getRemaining() { + return impl.getAvailIn(); + } + + /** + * 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. + * @return true if no data remains in the input buffer + */ + public boolean needsInput() { + return getRemaining() <= 0; + } + + /** + * Returns true if a preset dictionary is needed for decompression. + * @return true if a preset dictionary is needed for decompression + * @see Inflater#setDictionary + */ + public boolean needsDictionary() { + return impl.needDict(); + } + + /** + * Returns true if the end of the compressed data stream has been + * reached. + * @return true if the end of the compressed data stream has been + * reached + */ + public boolean finished() { + return impl.finished(); + } + + /** + * 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 latter case, getAdler() can be used to get the Adler-32 + * value of the dictionary required. + * @param b the buffer for the uncompressed data + * @param off the start offset of the data + * @param len the maximum number of uncompressed bytes + * @return the actual number of uncompressed bytes + * @exception DataFormatException if the compressed data format is invalid + * @see Inflater#needsInput + * @see Inflater#needsDictionary + */ + public int inflate(byte[] b, int off, int len) + throws DataFormatException + { + if (b == null) { + throw new NullPointerException(); + } + if (off < 0 || len < 0 || off > b.length - len) { + throw new ArrayIndexOutOfBoundsException(); + } + impl.setOutput(b, off, len); + int err = impl.inflate(JzLibInflater.Z_NO_FLUSH); + return impl.next_out_index - off; + } + + /** + * 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 latter case, getAdler() can be used to get the Adler-32 + * value of the dictionary required. + * @param b the buffer for the uncompressed data + * @return the actual number of uncompressed bytes + * @exception DataFormatException if the compressed data format is invalid + * @see Inflater#needsInput + * @see Inflater#needsDictionary + */ + public int inflate(byte[] b) throws DataFormatException { + return inflate(b, 0, b.length); + } + + /** + * Returns the ADLER-32 value of the uncompressed data. + * @return the ADLER-32 value of the uncompressed data + */ + public int getAdler() { + return (int) impl.getAdler(); + } + + /** + * Returns the total number of compressed bytes input so far. + * + *
Since the number of bytes may be greater than + * Integer.MAX_VALUE, the {@link #getBytesRead()} method is now + * the preferred means of obtaining this information.
+ * + * @return the total number of compressed bytes input so far + */ + public int getTotalIn() { + return (int) getBytesRead(); + } + + /** + * Returns the total number of compressed bytes input so far. + * + * @return the total (non-negative) number of compressed bytes input so far + * @since 1.5 + */ + public long getBytesRead() { + return impl.total_in; + } + + /** + * Returns the total number of uncompressed bytes output so far. + * + *Since the number of bytes may be greater than + * Integer.MAX_VALUE, the {@link #getBytesWritten()} method is now + * the preferred means of obtaining this information.
+ * + * @return the total number of uncompressed bytes output so far + */ + public int getTotalOut() { + return (int) getBytesWritten(); + } + + /** + * Returns the total number of uncompressed bytes output so far. + * + * @return the total (non-negative) number of uncompressed bytes output so far + * @since 1.5 + */ + public long getBytesWritten() { + return impl.total_out; + } + + /** + * Resets inflater so that a new set of input data can be processed. + */ + public void reset() { + impl = new JzLibInflater(15, nowrap); + } + + /** + * 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. + */ + public void end() { + impl.end(); + } + + /** + * Closes the decompressor when garbage is collected. + */ + protected void finalize() { + end(); + } +}