1 /* BufferedInputStream.java -- An input stream that implements buffering
2 Copyright (C) 1998, 1999, 2001, 2005 Free Software Foundation, Inc.
4 This file is part of GNU Classpath.
6 GNU Classpath is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU Classpath is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU Classpath; see the file COPYING. If not, write to the
18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 Linking this library statically or dynamically with other modules is
22 making a combined work based on this library. Thus, the terms and
23 conditions of the GNU General Public License cover the whole
26 As a special exception, the copyright holders of this library give you
27 permission to link this library with independent modules to produce an
28 executable, regardless of the license terms of these independent
29 modules, and to copy and distribute the resulting executable under
30 terms of your choice, provided that you also meet, for each linked
31 independent module, the terms and conditions of the license of that
32 module. An independent module is a module which is not derived from
33 or based on this library. If you modify this library, you may extend
34 this exception to your version of the library, but you are not
35 obligated to do so. If you do not wish to do so, delete this
36 exception statement from your version. */
38 /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
39 * "The Java Language Specification", ISBN 0-201-63451-1
40 * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
41 * Status: Believed complete and correct.
45 * This subclass of <code>FilterInputStream</code> buffers input from an
46 * underlying implementation to provide a possibly more efficient read
47 * mechanism. It maintains the buffer and buffer state in instance variables
48 * that are available to subclasses. The default buffer size of 2048 bytes can
49 * be overridden by the creator of the stream.
51 * This class also implements mark/reset functionality. It is capable of
52 * remembering any number of input bytes, to the limits of system memory or the
53 * size of <code>Integer.MAX_VALUE</code>
55 * Please note that this class does not properly handle character encodings.
56 * Consider using the <code>BufferedReader</code> class which does.
58 * @author Aaron M. Renn (arenn@urbanophile.com)
59 * @author Warren Levy (warrenl@cygnus.com)
60 * @author Jeroen Frijters (jeroen@frijters.net)
63 public class BufferedInputStream extends FilterInputStream {
66 * This is the default buffer size
68 private static final int DEFAULT_BUFFER_SIZE = 2048; // by default, it is TOP
71 * The buffer used for storing data from the underlying stream.
77 * The number of valid bytes currently in the buffer. It is also the index of
78 * the buffer position one byte past the end of the valid data.
84 * The index of the next character that will by read from the buffer. When
85 * <code>pos == count</code>, the buffer is empty.
91 * The value of <code>pos</code> when the <code>mark()</code> method was
92 * called. This is set to -1 if there is no mark set.
95 protected int markpos = -1;
98 * This is the maximum number of bytes than can be read after a call to
99 * <code>mark()</code> before the mark can be discarded. After this may bytes
100 * are read, the <code>reset()</code> method may not be called successfully.
102 protected int marklimit;
105 * This is the initial buffer size. When the buffer is grown because of
106 * marking requirements, it will be grown by bufferSize increments. The
107 * underlying stream will be read in chunks of bufferSize.
109 private final int bufferSize;
112 * This method initializes a new <code>BufferedInputStream</code> that will
113 * read from the specified subordinate stream with a default buffer size of
117 * The subordinate stream to read from
119 public BufferedInputStream(InputStream in) {
120 this(in, DEFAULT_BUFFER_SIZE);
124 * This method initializes a new <code>BufferedInputStream</code> that will
125 * read from the specified subordinate stream with a buffer size that is
126 * specified by the caller.
129 * The subordinate stream to read from
131 * The buffer size to use
133 * @exception IllegalArgumentException
134 * when size is smaller then 1
136 public BufferedInputStream(InputStream in, int size) {
139 throw new IllegalArgumentException();
140 buf = new byte[size];
141 // initialize pos & count to bufferSize, to prevent refill from
142 // allocating a new buffer (if the caller starts out by calling mark()).
143 pos = count = bufferSize = size;
147 * This method returns the number of bytes that can be read from this stream
148 * before a read can block. A return of 0 indicates that blocking might (or
149 * might not) occur on the very next read attempt.
151 * The number of available bytes will be the number of read ahead bytes stored
152 * in the internal buffer plus the number of available bytes in the underlying
155 * @return The number of bytes that can be read before blocking could occur
157 * @exception IOException
160 public synchronized int available() throws IOException {
161 return count - pos + super.available();
165 * This method closes the underlying input stream and frees any resources
166 * associated with it. Sets <code>buf</code> to <code>null</code>.
168 * @exception IOException
169 * If an error occurs.
171 public void close() throws IOException {
172 // Free up the array memory.
180 * This method marks a position in the input to which the stream can be
181 * "reset" by calling the <code>reset()</code> method. The parameter
182 * <code>readlimit</code> is the number of bytes that can be read from the
183 * stream after setting the mark before the mark becomes invalid. For example,
184 * if <code>mark()</code> is called with a read limit of 10, then when 11
185 * bytes of data are read from the stream before the <code>reset()</code>
186 * method is called, then the mark is invalid and the stream object instance
187 * is not required to remember the mark.
189 * Note that the number of bytes that can be remembered by this method can be
190 * greater than the size of the internal read buffer. It is also not dependent
191 * on the subordinate stream supporting mark/reset functionality.
194 * The number of bytes that can be read before the mark becomes
197 public synchronized void mark(int readlimit) {
198 marklimit = readlimit;
203 * This method returns <code>true</code> to indicate that this class supports
204 * mark/reset functionality.
206 * @return <code>true</code> to indicate that mark/reset functionality is
210 public boolean markSupported() {
215 * This method reads an unsigned byte from the input stream and returns it as
216 * an int in the range of 0-255. This method also will return -1 if the end of
217 * the stream has been reached.
219 * This method will block until the byte can be read.
221 * @return The byte read or -1 if end of stream
223 * @exception IOException
226 public synchronized int read() throws IOException {
227 if (pos >= count && !refill())
230 return buf[pos++] & 0xFF;
234 * This method reads bytes from a stream and stores them into a caller
235 * supplied buffer. It starts storing the data at index <code>off</code> into
236 * the buffer and attempts to read <code>len</code> bytes. This method can
237 * return before reading the number of bytes requested, but it will try to
238 * read the requested number of bytes by repeatedly calling the underlying
239 * stream as long as available() for this stream continues to return a
240 * non-zero value (or until the requested number of bytes have been read). The
241 * actual number of bytes read is returned as an int. A -1 is returned to
242 * indicate the end of the stream.
244 * This method will block until some data can be read.
247 * The array into which the bytes read should be stored
249 * The offset into the array to start storing bytes
251 * The requested number of bytes to read
253 * @return The actual number of bytes read, or -1 if end of stream.
255 * @exception IOException
256 * If an error occurs.
257 * @exception IndexOutOfBoundsException
258 * when <code>off</code> or <code>len</code> are negative, or
259 * when <code>off + len</code> is larger then the size of
262 public synchronized int read(byte[] b, int off, int len) throws IOException {
263 if (off < 0 || len < 0 || b.length - off < len)
264 // throw new IndexOutOfBoundsException();
270 if (pos >= count && !refill())
271 return -1; // No bytes were read before EOF.
273 int totalBytesRead = Math.min(count - pos, len);
274 System.arraycopy(buf, pos, b, off, totalBytesRead);
275 pos += totalBytesRead;
276 off += totalBytesRead;
277 len -= totalBytesRead;
279 while (len > 0 && super.available() > 0 && refill()) {
280 int remain = Math.min(count - pos, len);
281 System.arraycopy(buf, pos, b, off, remain);
285 totalBytesRead += remain;
288 return totalBytesRead;
292 * This method resets a stream to the point where the <code>mark()</code>
293 * method was called. Any bytes that were read after the mark point was set
294 * will be re-read during subsequent reads.
296 * This method will throw an IOException if the number of bytes read from the
297 * stream since the call to <code>mark()</code> exceeds the mark limit passed
298 * when establishing the mark.
300 * @exception IOException
301 * If <code>mark()</code> was never called or more then
302 * <code>marklimit</code> bytes were read since the last call to
303 * <code>mark()</code>
305 public synchronized void reset() throws IOException {
307 throw new IOException(buf == null ? "Stream closed." : "Invalid mark.");
313 * This method skips the specified number of bytes in the stream. It returns
314 * the actual number of bytes skipped, which may be less than the requested
318 * The requested number of bytes to skip
320 * @return The actual number of bytes skipped.
322 * @exception IOException
325 public synchronized long skip(long n) throws IOException {
327 throw new IOException("Stream closed.");
329 final long origN = n;
332 if (pos >= count && !refill())
335 int numread = (int) Math.min((long) (count - pos), n);
344 * Called to refill the buffer (when count is equal to pos).
346 * @return <code>true</code> when at least one additional byte was read into
347 * <code>buf</code>, <code>false</code> otherwise (at EOF).
349 private boolean refill() throws IOException {
351 throw new IOException("Stream closed.");
353 if (markpos == -1 || count - markpos >= marklimit) {
358 if (markpos < bufferSize) {
359 newbuf = new byte[count - markpos + bufferSize];
361 System.arraycopy(buf, markpos, newbuf, 0, count - markpos);
368 int numread = super.read(buf, count, bufferSize);
370 if (numread <= 0) // EOF