/* * Copyright (c) 1994, 2010, Oracle and/or its affiliates. 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.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.io; /** * A <code>ByteArrayInputStream</code> contains * an internal buffer that contains bytes that * may be read from the stream. An internal * counter keeps track of the next byte to * be supplied by the <code>read</code> method. * <p> * Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in * this class can be called after the stream has been closed without * generating an <tt>IOException</tt>. * * @author  Arthur van Hoff * @see     java.io.StringBufferInputStream * @since   JDK1.0 */publicclass ByteArrayInputStream extends InputStream {     /**     * An array of bytes that was provided     * by the creator of the stream. Elements <code>buf[0]</code>     * through <code>buf[count-1]</code> are the     * only bytes that can ever be read from the     * stream;  element <code>buf[pos]</code> is     * the next byte to be read.     */    protected byte buf[];     /**     * The index of the next character to read from the input stream buffer.     * This value should always be nonnegative     * and not larger than the value of <code>count</code>.     * The next byte to be read from the input stream buffer     * will be <code>buf[pos]</code>.     */    protected int pos;     /**     * The currently marked position in the stream.     * ByteArrayInputStream objects are marked at position zero by     * default when constructed.  They may be marked at another     * position within the buffer by the <code>mark()</code> method.     * The current buffer position is set to this point by the     * <code>reset()</code> method.     * <p>     * If no mark has been set, then the value of mark is the offset     * passed to the constructor (or 0 if the offset was not supplied).     *     * @since   JDK1.1     */    protected int mark = 0;     /**     * The index one greater than the last valid character in the input     * stream buffer.     * This value should always be nonnegative     * and not larger than the length of <code>buf</code>.     * It  is one greater than the position of     * the last byte within <code>buf</code> that     * can ever be read  from the input stream buffer.     */    protected int count;     /**     * Creates a <code>ByteArrayInputStream</code>     * so that it  uses <code>buf</code> as its     * buffer array.     * The buffer array is not copied.     * The initial value of <code>pos</code>     * is <code>0</code> and the initial value     * of  <code>count</code> is the length of     * <code>buf</code>.     *     * @param   buf   the input buffer.     */    public ByteArrayInputStream(byte buf[]) {        this.buf = buf;        this.pos = 0;        this.count = buf.length;    }     /**     * Creates <code>ByteArrayInputStream</code>     * that uses <code>buf</code> as its     * buffer array. The initial value of <code>pos</code>     * is <code>offset</code> and the initial value     * of <code>count</code> is the minimum of <code>offset+length</code>     * and <code>buf.length</code>.     * The buffer array is not copied. The buffer's mark is     * set to the specified offset.     *     * @param   buf      the input buffer.     * @param   offset   the offset in the buffer of the first byte to read.     * @param   length   the maximum number of bytes to read from the buffer.     */    public ByteArrayInputStream(byte buf[], int offset, int length) {        this.buf = buf;        this.pos = offset;        this.count = Math.min(offset + length, buf.length);        this.mark = offset;    }     /**     * Reads the next byte of data from this input stream. 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.     * <p>     * This <code>read</code> method     * cannot block.     *     * @return  the next byte of data, or <code>-1</code> if the end of the     *          stream has been reached.     */    public synchronized int read() {        return (pos < count) ? (buf[pos++] & 0xff) : -1;    }     /**     * Reads up to <code>len</code> bytes of data into an array of bytes     * from this input stream.     * If <code>pos</code> equals <code>count</code>,     * then <code>-1</code> is returned to indicate     * end of file. Otherwise, the  number <code>k</code>     * of bytes read is equal to the smaller of     * <code>len</code> and <code>count-pos</code>.     * If <code>k</code> is positive, then bytes     * <code>buf[pos]</code> through <code>buf[pos+k-1]</code>     * are copied into <code>b[off]</code>  through     * <code>b[off+k-1]</code> in the manner performed     * by <code>System.arraycopy</code>. The     * value <code>k</code> is added into <code>pos</code>     * and <code>k</code> is returned.     * <p>     * This <code>read</code> method cannot block.     *     * @param   b     the buffer into which the data is read.     * @param   off   the start offset in the destination array <code>b</code>     * @param   len   the maximum number of bytes read.     * @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.     * @exception  NullPointerException If <code>b</code> is <code>null</code>.     * @exception  IndexOutOfBoundsException If <code>off</code> is negative,     * <code>len</code> is negative, or <code>len</code> is greater than     * <code>b.length - off</code>     */    public synchronized int read(byte b[], int off, int len) {        if (b == null) {            throw new NullPointerException();        } else if (off < 0 || len < 0 || len > b.length - off) {            throw new IndexOutOfBoundsException();        }         if (pos >= count) {            return -1;        }         int avail = count - pos;        if (len > avail) {            len = avail;        }        if (len <= 0) {            return 0;        }        System.arraycopy(buf, pos, b, off, len);        pos += len;        return len;    }     /**     * Skips <code>n</code> bytes of input from this input stream. Fewer     * bytes might be skipped if the end of the input stream is reached.     * The actual number <code>k</code>     * of bytes to be skipped is equal to the smaller     * of <code>n</code> and  <code>count-pos</code>.     * The value <code>k</code> is added into <code>pos</code>     * and <code>k</code> is returned.     *     * @param   n   the number of bytes to be skipped.     * @return  the actual number of bytes skipped.     */    public synchronized long skip(long n) {        long k = count - pos;        if (n < k) {            k = n < 0 ? 0 : n;        }         pos += k;        return k;    }     /**     * Returns the number of remaining bytes that can be read (or skipped over)     * from this input stream.     * <p>     * The value returned is <code>count&nbsp;- pos</code>,     * which is the number of bytes remaining to be read from the input buffer.     *     * @return  the number of remaining bytes that can be read (or skipped     *          over) from this input stream without blocking.     */    public synchronized int available() {        return count - pos;    }     /**     * Tests if this <code>InputStream</code> supports mark/reset. The     * <code>markSupported</code> method of <code>ByteArrayInputStream</code>     * always returns <code>true</code>.     *     * @since   JDK1.1     */    public boolean markSupported() {        return true;    }     /**     * Set the current marked position in the stream.     * ByteArrayInputStream objects are marked at position zero by     * default when constructed.  They may be marked at another     * position within the buffer by this method.     * <p>     * If no mark has been set, then the value of the mark is the     * offset passed to the constructor (or 0 if the offset was not     * supplied).     *     * <p> Note: The <code>readAheadLimit</code> for this class     *  has no meaning.     *     * @since   JDK1.1     */    public void mark(int readAheadLimit) {        mark = pos;    }     /**     * Resets the buffer to the marked position.  The marked position     * is 0 unless another position was marked or an offset was specified     * in the constructor.     */    public synchronized void reset() {        pos = mark;    }     /**     * Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in     * this class can be called after the stream has been closed without     * generating an <tt>IOException</tt>.     * <p>     */    public void close() throws IOException {    } }