jdk/src/share/classes/java/util/zip/Inflater.java
changeset 2 90ce3da70b43
child 1158 34d64e750f8e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/zip/Inflater.java	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,364 @@
+/*
+ * Copyright 1996-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+package java.util.zip;
+
+/**
+ * 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 <a href="package-summary.html#package_description">java.util.zip
+ * package description</a>.
+ *
+ * <p>The following code fragment demonstrates a trivial compression
+ * and decompression of a string using <tt>Deflater</tt> and
+ * <tt>Inflater</tt>.
+ *
+ * <blockquote><pre>
+ * 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
+ * }
+ * </pre></blockquote>
+ *
+ * @see         Deflater
+ * @author      David Connelly
+ *
+ */
+public
+class Inflater {
+    private long strm;
+    private byte[] buf = new byte[0];
+    private int off, len;
+    private boolean finished;
+    private boolean needDict;
+
+    static {
+        /* Zip library is loaded from System.initializeSystemClass */
+        initIDs();
+    }
+
+    /**
+     * 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.
+     * <p>
+     * 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) {
+        strm = init(nowrap);
+    }
+
+    /**
+     * 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 synchronized 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();
+        }
+        this.buf = b;
+        this.off = off;
+        this.len = len;
+    }
+
+    /**
+     * 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 synchronized void setDictionary(byte[] b, int off, int len) {
+        if (strm == 0 || b == null) {
+            throw new NullPointerException();
+        }
+        if (off < 0 || len < 0 || off > b.length - len) {
+            throw new ArrayIndexOutOfBoundsException();
+        }
+        setDictionary(strm, b, off, len);
+        needDict = false;
+    }
+
+    /**
+     * 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) {
+        setDictionary(b, 0, 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 synchronized int getRemaining() {
+        return len;
+    }
+
+    /**
+     * 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 synchronized boolean needsInput() {
+        return len <= 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 synchronized boolean needsDictionary() {
+        return 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 synchronized boolean finished() {
+        return 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 synchronized 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();
+        }
+        return inflateBytes(b, off, len);
+    }
+
+    /**
+     * 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 synchronized int getAdler() {
+        ensureOpen();
+        return getAdler(strm);
+    }
+
+    /**
+     * Returns the total number of compressed bytes input so far.
+     *
+     * <p>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.</p>
+     *
+     * @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.</p>
+     *
+     * @return the total (non-negative) number of compressed bytes input so far
+     * @since 1.5
+     */
+    public synchronized long getBytesRead() {
+        ensureOpen();
+        return getBytesRead(strm);
+    }
+
+    /**
+     * Returns the total number of uncompressed bytes output so far.
+     *
+     * <p>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.</p>
+     *
+     * @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.</p>
+     *
+     * @return the total (non-negative) number of uncompressed bytes output so far
+     * @since 1.5
+     */
+    public synchronized long getBytesWritten() {
+        ensureOpen();
+        return getBytesWritten(strm);
+    }
+
+    /**
+     * Resets inflater so that a new set of input data can be processed.
+     */
+    public synchronized void reset() {
+        ensureOpen();
+        reset(strm);
+        finished = false;
+        needDict = false;
+        off = len = 0;
+    }
+
+    /**
+     * 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 synchronized void end() {
+        if (strm != 0) {
+            end(strm);
+            strm = 0;
+            buf = null;
+        }
+    }
+
+    /**
+     * Closes the decompressor when garbage is collected.
+     */
+    protected void finalize() {
+        end();
+    }
+
+    private void ensureOpen () {
+        if (strm == 0)
+            throw new NullPointerException();
+    }
+
+    private native static void initIDs();
+    private native static long init(boolean nowrap);
+    private native static void setDictionary(long strm, byte[] b, int off,
+                                             int len);
+    private native int inflateBytes(byte[] b, int off, int len)
+            throws DataFormatException;
+    private native static int getAdler(long strm);
+    private native static long getBytesRead(long strm);
+    private native static long getBytesWritten(long strm);
+    private native static void reset(long strm);
+    private native static void end(long strm);
+}