-/* Copyright (C) 1998, 1999 Free Software Foundation
+/* ByteArrayInputStream.java -- Read an array as a stream
+ Copyright (C) 1998, 1999, 2001, 2005 Free Software Foundation, Inc.
- This file is part of libgcj.
+This file is part of GNU Classpath.
-This software is copyrighted work licensed under the terms of the
-Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
-details. */
+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., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 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;
/**
- * @author Warren Levy <warrenl@cygnus.com>
- * @date October 7, 1998.
- */
-
-/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
- * "The Java Language Specification", ISBN 0-201-63451-1
- * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
- * Status: Believed complete and correct
- */
-
+ * 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
{
- /* An array of bytes provided by the creator of the stream. */
+ /**
+ * The array that contains the data supplied during read operations
+ */
protected byte[] buf;
- /* Position of the next byte in buf to be read. */
+ /**
+ * 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. */
+ /**
+ * 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;
- /* The index in buf one greater than the last valid character. */
+ /**
+ * 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;
count = buf.length;
pos = offset;
- // TBD: What should we do if pos is neg. or > count? E.g. throw exc. or:
- // if (pos < 0 || pos > count)
- // pos = 0;
-
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;
}
- public synchronized void mark(int readAheadLimit)
+ /**
+ * 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)
{
- // readAheadLimit is ignored per Java Class Lib. book, p.220.
+ // 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 < 0)
- throw new ArrayIndexOutOfBoundsException(pos);
-
if (pos < count)
return ((int) buf[pos++]) & 0xFF;
return -1;
}
- public synchronized int read(byte[] b, int off, int len)
+ /**
+ * 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)
{
- /* Don't need to check pos value, arraycopy will check it. */
- if (off < 0 || len < 0 || off + len > b.length)
- throw new ArrayIndexOutOfBoundsException();
-
if (pos >= count)
return -1;
- int numBytes = Math.min(count - pos, len);
- System.arraycopy(buf, pos, b, off, numBytes);
+ 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;
}
- public synchronized long skip(long n)
+ /**
+ * 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), n < 0 ? 0L : n);
+ long numBytes = Math.min((long) (count - pos), num < 0 ? 0L : num);
pos += numBytes;
return numBytes;
}
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