-/* Copyright (C) 1998, 1999, 2001 Free Software Foundation
+/* BufferedInputStream.java -- An input stream that implements buffering
+ Copyright (C) 1998, 1999, 2001 Free Software Foundation, Inc.
- This file is part of libgcj.
+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., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+As a special exception, if you link this library with other files to
+produce an executable, this library does not by itself cause the
+resulting executable to be covered by the GNU General Public License.
+This exception does not however invalidate any other reasons why the
+executable file might be covered by the GNU General Public License. */
-This software is copyrighted work licensed under the terms of the
-Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
-details. */
package java.io;
-/**
- * @author Warren Levy <warrenl@cygnus.com>
- * @date October 8, 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 subclass of <code>FilterInputStream</code> buffers input from an
+ * underlying implementation to provide a possibly more efficient read
+ * mechanism. It maintains the buffer and buffer state in instance
+ * variables that are available to subclasses. The default buffer size
+ * of 2048 bytes can be overridden by the creator of the stream.
+ * <p>
+ * This class also implements mark/reset functionality. It is capable
+ * of remembering any number of input bytes, to the limits of
+ * system memory or the size of <code>Integer.MAX_VALUE</code>
+ * <p>
+ * Please note that this class does not properly handle character
+ * encodings. Consider using the <code>BufferedReader</code> class which
+ * does.
+ *
+ * @author Aaron M. Renn (arenn@urbanophile.com)
+ * @author Warren Levy <warrenl@cygnus.com>
+ */
public class BufferedInputStream extends FilterInputStream
{
- /* Internal buffer array for data. */
+
+ /**
+ * This is the default buffer size
+ */
+ private static final int DEFAULT_BUFFER_SIZE = 2048;
+
+ /**
+ * The buffer used for storing data from the underlying stream.
+ */
protected byte[] buf;
- /* Index one greater than the last valid byte in the buffer. */
+ /**
+ * The number of valid bytes currently in the buffer. It is also the index
+ * of the buffer position one byte past the end of the valid data.
+ */
protected int count = 0;
- /* The current position in the buffer. */
+ /**
+ * The index of the next character that will by read from the buffer.
+ * When <code>pos == count</code>, the buffer is empty.
+ */
protected int pos = 0;
- /* The value of pos the last time mark() was called. */
+ /**
+ * The value of <code>pos</code> when the <code>mark()</code> method was
+ * called.
+ * This is set to -1 if there is no mark set.
+ */
protected int markpos = -1;
- /* The maximum read-ahead allowed before calls to reset() fail. */
+ /**
+ * This is the maximum number of bytes than can be read after a
+ * call to <code>mark()</code> before the mark can be discarded.
+ * After this may bytes are read, the <code>reset()</code> method
+ * may not be called successfully.
+ */
protected int marklimit = 0;
+ /**
+ * This method initializes a new <code>BufferedInputStream</code> that will
+ * read from the specified subordinate stream with a default buffer size
+ * of 2048 bytes
+ *
+ * @param in The subordinate stream to read from
+ */
public BufferedInputStream(InputStream in)
{
- this(in, 2048);
+ this(in, DEFAULT_BUFFER_SIZE);
}
+ /**
+ * This method initializes a new <code>BufferedInputStream</code> that will
+ * read from the specified subordinate stream with a buffer size that
+ * is specified by the caller.
+ *
+ * @param in The subordinate stream to read from
+ * @param size The buffer size to use
+ *
+ * @exception IllegalArgumentException when size is smaller then 1
+ */
public BufferedInputStream(InputStream in, int size)
{
super(in);
buf = new byte[size];
}
+ /**
+ * This method returns the number of bytes that can be read from this
+ * stream before a read can block. A return of 0 indicates that blocking
+ * might (or might not) occur on the very next read attempt.
+ * <p>
+ * The number of available bytes will be the number of read ahead bytes
+ * stored in the internal buffer plus the number of available bytes in
+ * the underlying stream.
+ *
+ * @return The number of bytes that can be read before blocking could occur
+ *
+ * @exception IOException If an error occurs
+ */
public synchronized int available() throws IOException
{
return count - pos + super.available();
}
+ /**
+ * This method closes the underlying input stream and frees any
+ * resources associated with it. Sets <code>buf</code> to <code>null</code>.
+ *
+ * @exception IOException If an error occurs.
+ */
public void close() throws IOException
{
// Free up the array memory.
super.close();
}
+ /**
+ * This method marks a position in the input to which the stream can be
+ * "reset" by calling the <code>reset()</code> method. The parameter
+ * <code>readlimit</code> is the number of bytes that can be read from the
+ * stream after setting the mark before the mark becomes invalid. For
+ * example, if <code>mark()</code> is called with a read limit of 10, then
+ * when 11 bytes of data are read from the stream before the
+ * <code>reset()</code> method is called, then the mark is invalid and the
+ * stream object instance is not required to remember the mark.
+ * <p>
+ * Note that the number of bytes that can be remembered by this method
+ * can be greater than the size of the internal read buffer. It is also
+ * not dependent on the subordinate stream supporting mark/reset
+ * functionality.
+ *
+ * @param readlimit The number of bytes that can be read before the mark
+ * becomes invalid
+ */
public synchronized void mark(int readlimit)
{
marklimit = readlimit;
markpos = pos;
}
+ /**
+ * This method returns <code>true</code> to indicate that this class
+ * supports mark/reset functionality.
+ *
+ * @return <code>true</code> to indicate that mark/reset functionality is
+ * supported
+ *
+ */
public boolean markSupported()
{
return true;
}
+ /**
+ * This method reads an unsigned byte from the input stream and returns it
+ * as an int in the range of 0-255. This method also will return -1 if
+ * the end of the stream has been reached.
+ * <p>
+ * This method will block until the byte can be read.
+ *
+ * @return The byte read or -1 if end of stream
+ *
+ * @exception IOException If an error occurs
+ */
public synchronized int read() throws IOException
{
if (pos >= count && !refill())
return ((int) buf[pos++]) & 0xFF;
}
+ /**
+ * This method reads bytes from a stream and stores them into a caller
+ * supplied buffer. It starts storing the data at index <code>off</code>
+ * into the buffer and attempts to read <code>len</code> bytes. This method
+ * can return before reading the number of bytes requested. The actual
+ * number of bytes read is returned as an int. A -1 is returned to indicate
+ * the end of the stream.
+ * <p>
+ * This method will block until some data can be read.
+ *
+ * @param b The array into which the bytes read should be stored
+ * @param off The offset into the array to start storing bytes
+ * @param len The requested number of bytes to read
+ *
+ * @return The actual number of bytes read, or -1 if end of stream.
+ *
+ * @exception IOException If an error occurs.
+ * @exception IndexOutOfBoundsException when <code>off</code> or
+ * <code>len</code> are negative, or when <code>off + len</code>
+ * is larger then the size of <code>b</code>,
+ */
public synchronized int read(byte[] b, int off, int len) throws IOException
{
if (off < 0 || len < 0 || off + len > b.length)
- throw new ArrayIndexOutOfBoundsException();
+ throw new IndexOutOfBoundsException();
if (pos >= count && !refill())
return -1; // No bytes were read before EOF.
return remain;
}
+ /**
+ * This method resets a stream to the point where the <code>mark()</code>
+ * method was called. Any bytes that were read after the mark point was
+ * set will be re-read during subsequent reads.
+ * <p>
+ * This method will throw an IOException if the number of bytes read from
+ * the stream since the call to <code>mark()</code> exceeds the mark limit
+ * passed when establishing the mark.
+ *
+ * @exception IOException If <code>mark()</code> was never called or more
+ * then <code>markLimit</code> bytes were read since the last
+ * call to <code>mark()</code>
+ */
public synchronized void reset() throws IOException
{
if (markpos < 0)
pos = markpos;
}
+ /**
+ * This method skips the specified number of bytes in the stream. It
+ * returns the actual number of bytes skipped, which may be less than the
+ * requested amount.
+ *
+ * @param n The requested number of bytes to skip
+ *
+ * @return The actual number of bytes skipped.
+ *
+ * @exception IOException If an error occurs
+ */
public synchronized long skip(long n) throws IOException
{
final long origN = n;
return origN - n;
}
+ /**
+ * Called to refill the buffer (when count is equal or greater the pos).
+ * Package local so BufferedReader can call it when needed.
+ *
+ * @return <code>true</code> when <code>buf</code> can be (partly) refilled,
+ * <code>false</code> otherwise.
+ */
boolean refill() throws IOException
{
if (markpos < 0)
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