author | redestad |
Tue, 22 Aug 2017 07:52:40 +0200 | |
changeset 46892 | fd5023dd3c85 |
parent 39121 | a1a92fce338a |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1994, 2016, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package java.io; |
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import jdk.internal.misc.Unsafe; |
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/** |
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* A <code>BufferedInputStream</code> adds |
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* functionality to another input stream-namely, |
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* the ability to buffer the input and to |
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* support the <code>mark</code> and <code>reset</code> |
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* methods. When the <code>BufferedInputStream</code> |
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* is created, an internal buffer array is |
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* created. As bytes from the stream are read |
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* or skipped, the internal buffer is refilled |
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* as necessary from the contained input stream, |
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* many bytes at a time. The <code>mark</code> |
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* operation remembers a point in the input |
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* stream and the <code>reset</code> operation |
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* causes all the bytes read since the most |
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* recent <code>mark</code> operation to be |
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* reread before new bytes are taken from |
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* the contained input stream. |
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* |
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* @author Arthur van Hoff |
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* @since 1.0 |
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*/ |
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public |
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class BufferedInputStream extends FilterInputStream { |
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private static int DEFAULT_BUFFER_SIZE = 8192; |
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/** |
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* The maximum size of array to allocate. |
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* Some VMs reserve some header words in an array. |
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* Attempts to allocate larger arrays may result in |
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* OutOfMemoryError: Requested array size exceeds VM limit |
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*/ |
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private static int MAX_BUFFER_SIZE = Integer.MAX_VALUE - 8; |
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/** |
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* As this class is used early during bootstrap, it's motivated to use |
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* Unsafe.compareAndSetObject instead of AtomicReferenceFieldUpdater |
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* (or VarHandles) to reduce dependencies and improve startup time. |
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*/ |
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private static final Unsafe U = Unsafe.getUnsafe(); |
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private static final long BUF_OFFSET |
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= U.objectFieldOffset(BufferedInputStream.class, "buf"); |
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/** |
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* The internal buffer array where the data is stored. When necessary, |
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* it may be replaced by another array of |
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* a different size. |
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*/ |
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/* |
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* We null this out with a CAS on close(), which is necessary since |
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* closes can be asynchronous. We use nullness of buf[] as primary |
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* indicator that this stream is closed. (The "in" field is also |
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* nulled out on close.) |
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*/ |
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protected volatile byte[] buf; |
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/** |
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* The index one greater than the index of the last valid byte in |
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* the buffer. |
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* This value is always |
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* in the range <code>0</code> through <code>buf.length</code>; |
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* elements <code>buf[0]</code> through <code>buf[count-1] |
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* </code>contain buffered input data obtained |
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* from the underlying input stream. |
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*/ |
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protected int count; |
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/** |
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* The current position in the buffer. This is the index of the next |
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* character to be read from the <code>buf</code> array. |
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* <p> |
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* This value is always in the range <code>0</code> |
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* through <code>count</code>. If it is less |
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* than <code>count</code>, then <code>buf[pos]</code> |
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* is the next byte to be supplied as input; |
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* if it is equal to <code>count</code>, then |
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* the next <code>read</code> or <code>skip</code> |
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* operation will require more bytes to be |
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* read from the contained input stream. |
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* |
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* @see java.io.BufferedInputStream#buf |
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*/ |
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protected int pos; |
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/** |
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* The value of the <code>pos</code> field at the time the last |
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* <code>mark</code> method was called. |
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* <p> |
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* This value is always |
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* in the range <code>-1</code> through <code>pos</code>. |
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* If there is no marked position in the input |
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* stream, this field is <code>-1</code>. If |
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* there is a marked position in the input |
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* stream, then <code>buf[markpos]</code> |
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* is the first byte to be supplied as input |
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* after a <code>reset</code> operation. If |
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* <code>markpos</code> is not <code>-1</code>, |
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* then all bytes from positions <code>buf[markpos]</code> |
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* through <code>buf[pos-1]</code> must remain |
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* in the buffer array (though they may be |
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* moved to another place in the buffer array, |
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* with suitable adjustments to the values |
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* of <code>count</code>, <code>pos</code>, |
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* and <code>markpos</code>); they may not |
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* be discarded unless and until the difference |
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* between <code>pos</code> and <code>markpos</code> |
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* exceeds <code>marklimit</code>. |
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* |
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* @see java.io.BufferedInputStream#mark(int) |
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* @see java.io.BufferedInputStream#pos |
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*/ |
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protected int markpos = -1; |
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/** |
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* The maximum read ahead allowed after a call to the |
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* <code>mark</code> method before subsequent calls to the |
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* <code>reset</code> method fail. |
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* Whenever the difference between <code>pos</code> |
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* and <code>markpos</code> exceeds <code>marklimit</code>, |
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* then the mark may be dropped by setting |
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* <code>markpos</code> to <code>-1</code>. |
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* |
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* @see java.io.BufferedInputStream#mark(int) |
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* @see java.io.BufferedInputStream#reset() |
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*/ |
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protected int marklimit; |
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/** |
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* Check to make sure that underlying input stream has not been |
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* nulled out due to close; if not return it; |
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*/ |
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private InputStream getInIfOpen() throws IOException { |
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InputStream input = in; |
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if (input == null) |
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throw new IOException("Stream closed"); |
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return input; |
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} |
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/** |
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* Check to make sure that buffer has not been nulled out due to |
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* close; if not return it; |
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*/ |
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private byte[] getBufIfOpen() throws IOException { |
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byte[] buffer = buf; |
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if (buffer == null) |
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throw new IOException("Stream closed"); |
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return buffer; |
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} |
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/** |
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* Creates a <code>BufferedInputStream</code> |
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* and saves its argument, the input stream |
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* <code>in</code>, for later use. An internal |
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* buffer array is created and stored in <code>buf</code>. |
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* |
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* @param in the underlying input stream. |
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*/ |
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public BufferedInputStream(InputStream in) { |
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this(in, DEFAULT_BUFFER_SIZE); |
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} |
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/** |
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* Creates a <code>BufferedInputStream</code> |
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* with the specified buffer size, |
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* and saves its argument, the input stream |
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* <code>in</code>, for later use. An internal |
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* buffer array of length <code>size</code> |
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* is created and stored in <code>buf</code>. |
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* |
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* @param in the underlying input stream. |
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* @param size the buffer size. |
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* @exception IllegalArgumentException if {@code size <= 0}. |
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*/ |
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public BufferedInputStream(InputStream in, int size) { |
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super(in); |
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if (size <= 0) { |
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throw new IllegalArgumentException("Buffer size <= 0"); |
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} |
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buf = new byte[size]; |
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} |
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/** |
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* Fills the buffer with more data, taking into account |
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* shuffling and other tricks for dealing with marks. |
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* Assumes that it is being called by a synchronized method. |
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* This method also assumes that all data has already been read in, |
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* hence pos > count. |
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*/ |
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private void fill() throws IOException { |
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byte[] buffer = getBufIfOpen(); |
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if (markpos < 0) |
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pos = 0; /* no mark: throw away the buffer */ |
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else if (pos >= buffer.length) /* no room left in buffer */ |
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if (markpos > 0) { /* can throw away early part of the buffer */ |
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int sz = pos - markpos; |
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System.arraycopy(buffer, markpos, buffer, 0, sz); |
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pos = sz; |
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markpos = 0; |
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} else if (buffer.length >= marklimit) { |
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markpos = -1; /* buffer got too big, invalidate mark */ |
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pos = 0; /* drop buffer contents */ |
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} else if (buffer.length >= MAX_BUFFER_SIZE) { |
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throw new OutOfMemoryError("Required array size too large"); |
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} else { /* grow buffer */ |
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int nsz = (pos <= MAX_BUFFER_SIZE - pos) ? |
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pos * 2 : MAX_BUFFER_SIZE; |
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if (nsz > marklimit) |
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nsz = marklimit; |
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byte[] nbuf = new byte[nsz]; |
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System.arraycopy(buffer, 0, nbuf, 0, pos); |
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if (!U.compareAndSetObject(this, BUF_OFFSET, buffer, nbuf)) { |
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// Can't replace buf if there was an async close. |
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// Note: This would need to be changed if fill() |
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// is ever made accessible to multiple threads. |
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// But for now, the only way CAS can fail is via close. |
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// assert buf == null; |
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throw new IOException("Stream closed"); |
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} |
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buffer = nbuf; |
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} |
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count = pos; |
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int n = getInIfOpen().read(buffer, pos, buffer.length - pos); |
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if (n > 0) |
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count = n + pos; |
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} |
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/** |
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* See |
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* the general contract of the <code>read</code> |
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* method of <code>InputStream</code>. |
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* |
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* @return the next byte of data, or <code>-1</code> if the end of the |
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* stream is reached. |
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* @exception IOException if this input stream has been closed by |
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* invoking its {@link #close()} method, |
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* or an I/O error occurs. |
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* @see java.io.FilterInputStream#in |
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*/ |
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public synchronized int read() throws IOException { |
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if (pos >= count) { |
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fill(); |
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if (pos >= count) |
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return -1; |
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} |
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return getBufIfOpen()[pos++] & 0xff; |
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} |
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/** |
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* Read characters into a portion of an array, reading from the underlying |
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* stream at most once if necessary. |
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*/ |
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private int read1(byte[] b, int off, int len) throws IOException { |
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int avail = count - pos; |
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if (avail <= 0) { |
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/* If the requested length is at least as large as the buffer, and |
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if there is no mark/reset activity, do not bother to copy the |
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bytes into the local buffer. In this way buffered streams will |
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cascade harmlessly. */ |
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if (len >= getBufIfOpen().length && markpos < 0) { |
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return getInIfOpen().read(b, off, len); |
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} |
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fill(); |
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avail = count - pos; |
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if (avail <= 0) return -1; |
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} |
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int cnt = (avail < len) ? avail : len; |
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System.arraycopy(getBufIfOpen(), pos, b, off, cnt); |
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pos += cnt; |
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return cnt; |
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} |
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/** |
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* Reads bytes from this byte-input stream into the specified byte array, |
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* starting at the given offset. |
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* |
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* <p> This method implements the general contract of the corresponding |
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* <code>{@link InputStream#read(byte[], int, int) read}</code> method of |
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* the <code>{@link InputStream}</code> class. As an additional |
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* convenience, it attempts to read as many bytes as possible by repeatedly |
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* invoking the <code>read</code> method of the underlying stream. This |
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* iterated <code>read</code> continues until one of the following |
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* conditions becomes true: <ul> |
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* |
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* <li> The specified number of bytes have been read, |
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* |
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* <li> The <code>read</code> method of the underlying stream returns |
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* <code>-1</code>, indicating end-of-file, or |
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* |
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* <li> The <code>available</code> method of the underlying stream |
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* returns zero, indicating that further input requests would block. |
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* |
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* </ul> If the first <code>read</code> on the underlying stream returns |
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* <code>-1</code> to indicate end-of-file then this method returns |
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* <code>-1</code>. Otherwise this method returns the number of bytes |
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* actually read. |
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* |
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* <p> Subclasses of this class are encouraged, but not required, to |
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* attempt to read as many bytes as possible in the same fashion. |
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* |
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330 |
* @param b destination buffer. |
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* @param off offset at which to start storing bytes. |
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332 |
* @param len maximum number of bytes to read. |
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333 |
* @return the number of bytes read, or <code>-1</code> if the end of |
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* the stream has been reached. |
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335 |
* @exception IOException if this input stream has been closed by |
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336 |
* invoking its {@link #close()} method, |
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* or an I/O error occurs. |
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*/ |
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public synchronized int read(byte b[], int off, int len) |
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throws IOException |
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341 |
{ |
|
342 |
getBufIfOpen(); // Check for closed stream |
|
343 |
if ((off | len | (off + len) | (b.length - (off + len))) < 0) { |
|
344 |
throw new IndexOutOfBoundsException(); |
|
345 |
} else if (len == 0) { |
|
346 |
return 0; |
|
347 |
} |
|
348 |
||
349 |
int n = 0; |
|
350 |
for (;;) { |
|
351 |
int nread = read1(b, off + n, len - n); |
|
352 |
if (nread <= 0) |
|
353 |
return (n == 0) ? nread : n; |
|
354 |
n += nread; |
|
355 |
if (n >= len) |
|
356 |
return n; |
|
357 |
// if not closed but no bytes available, return |
|
358 |
InputStream input = in; |
|
359 |
if (input != null && input.available() <= 0) |
|
360 |
return n; |
|
361 |
} |
|
362 |
} |
|
363 |
||
364 |
/** |
|
365 |
* See the general contract of the <code>skip</code> |
|
366 |
* method of <code>InputStream</code>. |
|
367 |
* |
|
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8136738: InputStream documentation for IOException in skip() is unclear or incorrect
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changeset
|
368 |
* @throws IOException if this input stream has been closed by |
a1a92fce338a
8136738: InputStream documentation for IOException in skip() is unclear or incorrect
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parents:
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diff
changeset
|
369 |
* invoking its {@link #close()} method, |
a1a92fce338a
8136738: InputStream documentation for IOException in skip() is unclear or incorrect
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diff
changeset
|
370 |
* {@code in.skip(n)} throws an IOException, |
a1a92fce338a
8136738: InputStream documentation for IOException in skip() is unclear or incorrect
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|
371 |
* or an I/O error occurs. |
2 | 372 |
*/ |
373 |
public synchronized long skip(long n) throws IOException { |
|
374 |
getBufIfOpen(); // Check for closed stream |
|
375 |
if (n <= 0) { |
|
376 |
return 0; |
|
377 |
} |
|
378 |
long avail = count - pos; |
|
379 |
||
380 |
if (avail <= 0) { |
|
381 |
// If no mark position set then don't keep in buffer |
|
382 |
if (markpos <0) |
|
383 |
return getInIfOpen().skip(n); |
|
384 |
||
385 |
// Fill in buffer to save bytes for reset |
|
386 |
fill(); |
|
387 |
avail = count - pos; |
|
388 |
if (avail <= 0) |
|
389 |
return 0; |
|
390 |
} |
|
391 |
||
392 |
long skipped = (avail < n) ? avail : n; |
|
393 |
pos += skipped; |
|
394 |
return skipped; |
|
395 |
} |
|
396 |
||
397 |
/** |
|
398 |
* Returns an estimate of the number of bytes that can be read (or |
|
399 |
* skipped over) from this input stream without blocking by the next |
|
400 |
* invocation of a method for this input stream. The next invocation might be |
|
401 |
* the same thread or another thread. A single read or skip of this |
|
402 |
* many bytes will not block, but may read or skip fewer bytes. |
|
403 |
* <p> |
|
404 |
* This method returns the sum of the number of bytes remaining to be read in |
|
405 |
* the buffer (<code>count - pos</code>) and the result of calling the |
|
406 |
* {@link java.io.FilterInputStream#in in}.available(). |
|
407 |
* |
|
408 |
* @return an estimate of the number of bytes that can be read (or skipped |
|
409 |
* over) from this input stream without blocking. |
|
410 |
* @exception IOException if this input stream has been closed by |
|
411 |
* invoking its {@link #close()} method, |
|
412 |
* or an I/O error occurs. |
|
413 |
*/ |
|
414 |
public synchronized int available() throws IOException { |
|
7280
81f10887bf74
6631046: BufferedInputStream.available() reports negative int on very large inputstream
mchung
parents:
5506
diff
changeset
|
415 |
int n = count - pos; |
81f10887bf74
6631046: BufferedInputStream.available() reports negative int on very large inputstream
mchung
parents:
5506
diff
changeset
|
416 |
int avail = getInIfOpen().available(); |
81f10887bf74
6631046: BufferedInputStream.available() reports negative int on very large inputstream
mchung
parents:
5506
diff
changeset
|
417 |
return n > (Integer.MAX_VALUE - avail) |
81f10887bf74
6631046: BufferedInputStream.available() reports negative int on very large inputstream
mchung
parents:
5506
diff
changeset
|
418 |
? Integer.MAX_VALUE |
81f10887bf74
6631046: BufferedInputStream.available() reports negative int on very large inputstream
mchung
parents:
5506
diff
changeset
|
419 |
: n + avail; |
2 | 420 |
} |
421 |
||
422 |
/** |
|
423 |
* See the general contract of the <code>mark</code> |
|
424 |
* method of <code>InputStream</code>. |
|
425 |
* |
|
426 |
* @param readlimit the maximum limit of bytes that can be read before |
|
427 |
* the mark position becomes invalid. |
|
428 |
* @see java.io.BufferedInputStream#reset() |
|
429 |
*/ |
|
430 |
public synchronized void mark(int readlimit) { |
|
431 |
marklimit = readlimit; |
|
432 |
markpos = pos; |
|
433 |
} |
|
434 |
||
435 |
/** |
|
436 |
* See the general contract of the <code>reset</code> |
|
437 |
* method of <code>InputStream</code>. |
|
438 |
* <p> |
|
439 |
* If <code>markpos</code> is <code>-1</code> |
|
440 |
* (no mark has been set or the mark has been |
|
441 |
* invalidated), an <code>IOException</code> |
|
442 |
* is thrown. Otherwise, <code>pos</code> is |
|
443 |
* set equal to <code>markpos</code>. |
|
444 |
* |
|
445 |
* @exception IOException if this stream has not been marked or, |
|
446 |
* if the mark has been invalidated, or the stream |
|
447 |
* has been closed by invoking its {@link #close()} |
|
448 |
* method, or an I/O error occurs. |
|
449 |
* @see java.io.BufferedInputStream#mark(int) |
|
450 |
*/ |
|
451 |
public synchronized void reset() throws IOException { |
|
452 |
getBufIfOpen(); // Cause exception if closed |
|
453 |
if (markpos < 0) |
|
454 |
throw new IOException("Resetting to invalid mark"); |
|
455 |
pos = markpos; |
|
456 |
} |
|
457 |
||
458 |
/** |
|
459 |
* Tests if this input stream supports the <code>mark</code> |
|
460 |
* and <code>reset</code> methods. The <code>markSupported</code> |
|
461 |
* method of <code>BufferedInputStream</code> returns |
|
462 |
* <code>true</code>. |
|
463 |
* |
|
464 |
* @return a <code>boolean</code> indicating if this stream type supports |
|
465 |
* the <code>mark</code> and <code>reset</code> methods. |
|
466 |
* @see java.io.InputStream#mark(int) |
|
467 |
* @see java.io.InputStream#reset() |
|
468 |
*/ |
|
469 |
public boolean markSupported() { |
|
470 |
return true; |
|
471 |
} |
|
472 |
||
473 |
/** |
|
474 |
* Closes this input stream and releases any system resources |
|
475 |
* associated with the stream. |
|
476 |
* Once the stream has been closed, further read(), available(), reset(), |
|
477 |
* or skip() invocations will throw an IOException. |
|
478 |
* Closing a previously closed stream has no effect. |
|
479 |
* |
|
480 |
* @exception IOException if an I/O error occurs. |
|
481 |
*/ |
|
482 |
public void close() throws IOException { |
|
483 |
byte[] buffer; |
|
484 |
while ( (buffer = buf) != null) { |
|
46892
fd5023dd3c85
8185362: Replace use of AtomicReferenceFieldUpdater from BufferedInputStream with Unsafe
redestad
parents:
39121
diff
changeset
|
485 |
if (U.compareAndSetObject(this, BUF_OFFSET, buffer, null)) { |
2 | 486 |
InputStream input = in; |
487 |
in = null; |
|
488 |
if (input != null) |
|
489 |
input.close(); |
|
490 |
return; |
|
491 |
} |
|
492 |
// Else retry in case a new buf was CASed in fill() |
|
493 |
} |
|
494 |
} |
|
495 |
} |