| /* ByteArrayInputStream.java -- Read an array as a stream |
| Copyright (C) 1998, 1999, 2001, 2005 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.io; |
| |
| /** |
| * This class permits an array of bytes to be read as an input stream. |
| * |
| * @author Warren Levy (warrenl@cygnus.com) |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| */ |
| public class ByteArrayInputStream extends InputStream |
| { |
| /** |
| * The array that contains the data supplied during read operations |
| */ |
| protected byte[] buf; |
| |
| /** |
| * The array index of the next byte to be read from the buffer |
| * <code>buf</code> |
| */ |
| protected int pos; |
| |
| /** |
| * The currently marked position in the stream. This defaults to 0, so a |
| * reset operation on the stream resets it to read from array index 0 in |
| * the buffer - even if the stream was initially created with an offset |
| * greater than 0 |
| */ |
| protected int mark; |
| |
| /** |
| * This indicates the maximum number of bytes that can be read from this |
| * stream. It is the array index of the position after the last valid |
| * byte in the buffer <code>buf</code> |
| */ |
| protected int count; |
| |
| /** |
| * Create a new ByteArrayInputStream that will read bytes from the passed |
| * in byte array. This stream will read from the beginning to the end |
| * of the array. It is identical to calling an overloaded constructor |
| * as <code>ByteArrayInputStream(buf, 0, buf.length)</code>. |
| * <p> |
| * Note that this array is not copied. If its contents are changed |
| * while this stream is being read, those changes will be reflected in the |
| * bytes supplied to the reader. Please use caution in changing the |
| * contents of the buffer while this stream is open. |
| * |
| * @param buffer The byte array buffer this stream will read from. |
| */ |
| public ByteArrayInputStream(byte[] buffer) |
| { |
| this(buffer, 0, buffer.length); |
| } |
| |
| /** |
| * Create a new ByteArrayInputStream that will read bytes from the |
| * passed in byte array. This stream will read from position |
| * <code>offset</code> in the array for a length of |
| * <code>length</code> bytes past <code>offset</code>. If the |
| * stream is reset to a position before <code>offset</code> then |
| * more than <code>length</code> bytes can be read from the stream. |
| * The <code>length</code> value should be viewed as the array index |
| * one greater than the last position in the buffer to read. |
| * <p> |
| * Note that this array is not copied. If its contents are changed |
| * while this stream is being read, those changes will be reflected in the |
| * bytes supplied to the reader. Please use caution in changing the |
| * contents of the buffer while this stream is open. |
| * |
| * @param buffer The byte array buffer this stream will read from. |
| * @param offset The index into the buffer to start reading bytes from |
| * @param length The number of bytes to read from the buffer |
| */ |
| public ByteArrayInputStream(byte[] buffer, int offset, int length) |
| { |
| if (offset < 0 || length < 0 || offset > buffer.length) |
| throw new IllegalArgumentException(); |
| |
| buf = buffer; |
| |
| count = offset + length; |
| if (count > buf.length) |
| count = buf.length; |
| |
| pos = offset; |
| mark = pos; |
| } |
| |
| /** |
| * This method returns the number of bytes available to be read from this |
| * stream. The value returned will be equal to <code>count - pos</code>. |
| * |
| * @return The number of bytes that can be read from this stream |
| * before blocking, which is all of them |
| */ |
| public synchronized int available() |
| { |
| return count - pos; |
| } |
| |
| /** |
| * This method sets the mark position in this stream to the current |
| * position. Note that the <code>readlimit</code> parameter in this |
| * method does nothing as this stream is always capable of |
| * remembering all the bytes int it. |
| * <p> |
| * Note that in this class the mark position is set by default to |
| * position 0 in the stream. This is in constrast to some other |
| * stream types where there is no default mark position. |
| * |
| * @param readLimit The number of bytes this stream must remember. |
| * This parameter is ignored. |
| */ |
| public synchronized void mark(int readLimit) |
| { |
| // readLimit is ignored per Java Class Lib. book, p.220. |
| mark = pos; |
| } |
| |
| /** |
| * This method overrides the <code>markSupported</code> method in |
| * <code>InputStream</code> in order to return <code>true</code> - |
| * indicating that this stream class supports mark/reset |
| * functionality. |
| * |
| * @return <code>true</code> to indicate that this class supports |
| * mark/reset. |
| */ |
| public boolean markSupported() |
| { |
| return true; |
| } |
| |
| /** |
| * This method reads one byte from the stream. The <code>pos</code> |
| * counter is advanced to the next byte to be read. The byte read is |
| * returned as an int in the range of 0-255. If the stream position |
| * is already at the end of the buffer, no byte is read and a -1 is |
| * returned in order to indicate the end of the stream. |
| * |
| * @return The byte read, or -1 if end of stream |
| */ |
| public synchronized int read() |
| { |
| if (pos < count) |
| return ((int) buf[pos++]) & 0xFF; |
| return -1; |
| } |
| |
| /** |
| * This method reads bytes from the stream and stores them into a |
| * caller supplied buffer. It starts storing the data at index |
| * <code>offset</code> into the buffer and attempts to read |
| * <code>len</code> bytes. This method can return before reading |
| * the number of bytes requested if the end of the stream is |
| * encountered first. The actual number of bytes read is returned. |
| * If no bytes can be read because the stream is already at the end |
| * of stream position, a -1 is returned. |
| * <p> |
| * This method does not block. |
| * |
| * @param buffer The array into which the bytes read should be stored. |
| * @param offset The offset into the array to start storing bytes |
| * @param length The requested number of bytes to read |
| * |
| * @return The actual number of bytes read, or -1 if end of stream. |
| */ |
| public synchronized int read(byte[] buffer, int offset, int length) |
| { |
| if (pos >= count) |
| return -1; |
| |
| int numBytes = Math.min(count - pos, length); |
| System.arraycopy(buf, pos, buffer, offset, numBytes); |
| pos += numBytes; |
| return numBytes; |
| } |
| |
| /** |
| * This method sets the read position in the stream to the mark |
| * point by setting the <code>pos</code> variable equal to the |
| * <code>mark</code> variable. Since a mark can be set anywhere in |
| * the array, the mark/reset methods int this class can be used to |
| * provide random search capabilities for this type of stream. |
| */ |
| public synchronized void reset() |
| { |
| pos = mark; |
| } |
| |
| /** |
| * This method attempts to skip the requested number of bytes in the |
| * input stream. It does this by advancing the <code>pos</code> |
| * value by the specified number of bytes. It this would exceed the |
| * length of the buffer, then only enough bytes are skipped to |
| * position the stream at the end of the buffer. The actual number |
| * of bytes skipped is returned. |
| * |
| * @param num The requested number of bytes to skip |
| * |
| * @return The actual number of bytes skipped. |
| */ |
| public synchronized long skip(long num) |
| { |
| // Even though the var numBytes is a long, in reality it can never |
| // be larger than an int since the result of subtracting 2 positive |
| // ints will always fit in an int. Since we have to return a long |
| // anyway, numBytes might as well just be a long. |
| long numBytes = Math.min((long) (count - pos), num < 0 ? 0L : num); |
| pos += numBytes; |
| return numBytes; |
| } |
| } |