ByteArraySeekableStream.java
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- /*
- * Copyright (c) 2001 Sun Microsystems, Inc. All Rights Reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * -Redistributions of source code must retain the above copyright notice, this
- * list of conditions and the following disclaimer.
- *
- * -Redistribution in binary form must reproduct the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * Neither the name of Sun Microsystems, Inc. or the names of contributors may
- * be used to endorse or promote products derived from this software without
- * specific prior written permission.
- *
- * This software is provided "AS IS," without a warranty of any kind. ALL
- * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
- * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
- * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
- * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
- * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
- * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
- * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
- * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
- * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGES.
- *
- * You acknowledge that Software is not designed,licensed or intended for use in
- * the design, construction, operation or maintenance of any nuclear facility.
- */
- import java.io.InputStream;
- import java.io.IOException;
- /**
- * A subclass of <code>SeekableStream</code> that takes input from an
- * array of bytes. Seeking backwards is supported. The
- * <code>mark()</code> and <code>resest()</code> methods are
- * supported.
- *
- * <p><b> This class is not a committed part of the JAI API. It may
- * be removed or changed in future releases of JAI.</b>
- */
- public class ByteArraySeekableStream extends SeekableStream {
- /** Array holding the source data. */
- private byte[] src;
- /** The starting offset within the array. */
- private int offset;
- /** The length of the valid segment of the array. */
- private int length;
-
- /** The current output position. */
- private int pointer;
- /**
- * Constructs a <code>ByteArraySeekableStream</code> taking
- * input from a given segment of an input <code>byte</code> array.
- */
- public ByteArraySeekableStream(byte[] src, int offset, int length)
- throws IOException {
- this.src = src;
- this.offset = offset;
- this.length = length;
- }
- /**
- * Constructs a <code>ByteArraySeekableStream</code> taking
- * input from an entire input <code>byte</code> array.
- */
- public ByteArraySeekableStream(byte[] src) throws IOException {
- this(src, 0, src.length);
- }
- /**
- * Returns <code>true</code> since this object supports seeking
- * backwards.
- */
- public boolean canSeekBackwards() {
- return true;
- }
- /**
- * Returns the current offset in this stream.
- *
- * @return the offset from the beginning of the stream, in bytes,
- * at which the next read occurs.
- */
- public long getFilePointer() {
- return (long)pointer;
- }
- /**
- * Sets the offset, measured from the beginning of this
- * stream, at which the next read occurs. Seeking backwards is
- * allowed.
- *
- * @param pos the offset position, measured in bytes from the
- * beginning of the stream, at which to set the stream
- * pointer.
- */
- public void seek(long pos) {
- pointer = (int)pos;
- }
- /**
- * Reads the next byte of data from the input array. The value byte is
- * returned as an <code>int</code> in the range <code>0</code> to
- * <code>255</code>. If no byte is available because the end of the stream
- * has been reached, the value <code>-1</code> is returned.
- */
- public int read() {
- if (pointer < length + offset) {
- return (int)(src[pointer++ + offset] & 0xff);
- } else {
- return -1;
- }
- }
- /**
- * Copies up to <code>len</code> bytes of data from the input array into
- * an array of bytes. An attempt is made to copy as many as
- * <code>len</code> bytes, but a smaller number may be copied, possibly
- * zero. The number of bytes actually copied is returned as an integer.
- *
- * <p> If <code>b</code> is <code>null</code>, a
- * <code>NullPointerException</code> is thrown.
- *
- * <p> If <code>off</code> is negative, or <code>len</code> is negative, or
- * <code>off+len</code> is greater than the length of the array
- * <code>b</code>, then an <code>IndexOutOfBoundsException</code> is
- * thrown.
- *
- * <p> If <code>len</code> is zero, then no bytes are copied and
- * <code>0</code> is returned; otherwise, there is an attempt to copy at
- * least one byte. If no byte is available because the stream is at end of
- * stream, the value <code>-1</code> is returned; otherwise, at least one
- * byte is copied into <code>b</code>.
- *
- * <p> The first byte copied is stored into element
- * <code>b[off]</code>, the next one into <code>b[off+1]</code>,
- * and so on. The number of bytes copied is, at most, equal to
- * <code>len</code>. Let <i>k</i> be the number of bytes actually
- * copied; these bytes will be stored in elements
- * <code>b[off]</code> through
- * <code>b[off+</code><i>k</i><code>-1]</code>, leaving elements
- * <code>b[off+</code><i>k</i><code>]</code> through
- * <code>b[off+len-1]</code> unaffected.
- *
- * <p> In every case, elements <code>b[0]</code> through
- * <code>b[off]</code> and elements <code>b[off+len]</code> through
- * <code>b[b.length-1]</code> are unaffected.
- *
- * @param b the buffer into which the data is copied.
- * @param off the start offset in array <code>b</code>
- * at which the data is written.
- * @param len the maximum number of bytes to copy.
- * @return the total number of bytes read into the buffer, or
- * <code>-1</code> if there is no more data because the end of
- * the stream has been reached.
- */
- public int read(byte[] b, int off, int len) {
- if (b == null) {
- throw new NullPointerException();
- }
- if ((off < 0) || (len < 0) || (off + len > b.length)) {
- throw new IndexOutOfBoundsException();
- }
- if (len == 0) {
- return 0;
- }
- int oldPointer = pointer;
- pointer = Math.min(pointer + len, length + offset);
- if (pointer == oldPointer) {
- return -1;
- } else {
- System.arraycopy(src, oldPointer, b, off, pointer - oldPointer);
- return pointer - oldPointer;
- }
- }
- /**
- * Attempts to skip over <code>n</code> bytes of input discarding the
- * skipped bytes.
- * <p>
- *
- * This method may skip over some smaller number of bytes, possibly zero.
- * This may result from any of a number of conditions; reaching end of
- * stream before <code>n</code> bytes have been skipped is only one
- * possibility. This method never throws an <code>EOFException</code>.
- * The actual number of bytes skipped is returned. If <code>n</code>
- * is negative, no bytes are skipped.
- *
- * @param n the number of bytes to be skipped.
- * @return the actual number of bytes skipped.
- */
- public int skipBytes(int n) {
- int oldPointer = pointer;
- pointer = Math.min(pointer + n, length + offset);
- return pointer - oldPointer;
- }
- /** Does nothing. */
- public void close() {
- }
- /** Returns the number of valid bytes in the input array. */
- public long length() {
- return length;
- }
- }