author | jlahoda |
Mon, 30 Apr 2018 15:03:08 +0200 | |
changeset 49924 | 84d0fe3cefd4 |
parent 49262 | 1b3ee04e3e54 |
child 50770 | c545db4fc9bd |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1996, 2018, 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 java.nio.CharBuffer; |
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import java.util.Objects; |
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/** |
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* Abstract class for reading character streams. The only methods that a |
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* subclass must implement are read(char[], int, int) and close(). Most |
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* subclasses, however, will override some of the methods defined here in order |
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* to provide higher efficiency, additional functionality, or both. |
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* |
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* |
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* @see BufferedReader |
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* @see LineNumberReader |
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* @see CharArrayReader |
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* @see InputStreamReader |
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* @see FileReader |
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* @see FilterReader |
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* @see PushbackReader |
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* @see PipedReader |
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* @see StringReader |
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* @see Writer |
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* |
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* @author Mark Reinhold |
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* @since 1.1 |
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*/ |
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public abstract class Reader implements Readable, Closeable { |
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private static final int TRANSFER_BUFFER_SIZE = 8192; |
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/** |
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* Returns a new {@code Reader} that reads no characters. The returned |
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* stream is initially open. The stream is closed by calling the |
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* {@code close()} method. Subsequent calls to {@code close()} have no |
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* effect. |
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* |
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* <p> While the stream is open, the {@code read()}, {@code read(char[])}, |
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* {@code read(char[], int, int)}, {@code read(Charbuffer)}, {@code |
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* ready())}, {@code skip(long)}, and {@code transferTo()} methods all |
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* behave as if end of stream has been reached. After the stream has been |
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* closed, these methods all throw {@code IOException}. |
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* |
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* <p> The {@code markSupported()} method returns {@code false}. The |
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* {@code mark()} method does nothing, and the {@code reset()} method |
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* throws {@code IOException}. |
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* |
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* <p> The {@link #lock object} used to synchronize operations on the |
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* returned {@code Reader} is not specified. |
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* |
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* @return a {@code Reader} which reads no characters |
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* |
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* @since 11 |
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*/ |
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public static Reader nullReader() { |
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return new Reader() { |
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private volatile boolean closed; |
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private void ensureOpen() throws IOException { |
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if (closed) { |
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throw new IOException("Stream closed"); |
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} |
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} |
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@Override |
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public int read() throws IOException { |
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ensureOpen(); |
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return -1; |
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} |
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@Override |
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public int read(char[] cbuf, int off, int len) throws IOException { |
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Objects.checkFromIndexSize(off, len, cbuf.length); |
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ensureOpen(); |
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if (len == 0) { |
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return 0; |
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} |
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return -1; |
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} |
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@Override |
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public int read(CharBuffer target) throws IOException { |
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Objects.requireNonNull(target); |
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ensureOpen(); |
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if (target.hasRemaining()) { |
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return -1; |
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} |
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return 0; |
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} |
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@Override |
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public long skip(long n) throws IOException { |
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ensureOpen(); |
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return 0L; |
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} |
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@Override |
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public long transferTo(Writer out) throws IOException { |
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Objects.requireNonNull(out); |
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ensureOpen(); |
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return 0L; |
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} |
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@Override |
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public void close() { |
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closed = true; |
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} |
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}; |
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} |
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/** |
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* The object used to synchronize operations on this stream. For |
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* efficiency, a character-stream object may use an object other than |
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* itself to protect critical sections. A subclass should therefore use |
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* the object in this field rather than {@code this} or a synchronized |
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* method. |
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*/ |
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protected Object lock; |
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/** |
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* Creates a new character-stream reader whose critical sections will |
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* synchronize on the reader itself. |
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*/ |
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protected Reader() { |
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this.lock = this; |
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} |
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/** |
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* Creates a new character-stream reader whose critical sections will |
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* synchronize on the given object. |
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* |
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* @param lock The Object to synchronize on. |
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*/ |
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protected Reader(Object lock) { |
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if (lock == null) { |
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throw new NullPointerException(); |
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} |
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this.lock = lock; |
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} |
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/** |
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* Attempts to read characters into the specified character buffer. |
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* The buffer is used as a repository of characters as-is: the only |
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* changes made are the results of a put operation. No flipping or |
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* rewinding of the buffer is performed. |
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* |
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* @param target the buffer to read characters into |
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* @return The number of characters added to the buffer, or |
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* -1 if this source of characters is at its end |
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* @throws IOException if an I/O error occurs |
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* @throws NullPointerException if target is null |
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* @throws java.nio.ReadOnlyBufferException if target is a read only buffer |
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* @since 1.5 |
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*/ |
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public int read(java.nio.CharBuffer target) throws IOException { |
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int len = target.remaining(); |
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char[] cbuf = new char[len]; |
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int n = read(cbuf, 0, len); |
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if (n > 0) |
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target.put(cbuf, 0, n); |
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return n; |
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} |
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/** |
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* Reads a single character. This method will block until a character is |
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* available, an I/O error occurs, or the end of the stream is reached. |
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* |
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* <p> Subclasses that intend to support efficient single-character input |
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* should override this method. |
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* |
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* @return The character read, as an integer in the range 0 to 65535 |
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avstepan
parents:
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* ({@code 0x00-0xffff}), or -1 if the end of the stream has |
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* been reached |
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* |
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* @exception IOException If an I/O error occurs |
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*/ |
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public int read() throws IOException { |
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char cb[] = new char[1]; |
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if (read(cb, 0, 1) == -1) |
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return -1; |
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else |
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return cb[0]; |
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} |
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/** |
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* Reads characters into an array. This method will block until some input |
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* is available, an I/O error occurs, or the end of the stream is reached. |
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* |
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* @param cbuf Destination buffer |
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* |
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* @return The number of characters read, or -1 |
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* if the end of the stream |
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* has been reached |
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* |
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* @exception IOException If an I/O error occurs |
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*/ |
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public int read(char cbuf[]) throws IOException { |
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return read(cbuf, 0, cbuf.length); |
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} |
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/** |
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* Reads characters into a portion of an array. This method will block |
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* until some input is available, an I/O error occurs, or the end of the |
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* stream is reached. |
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* |
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* @param cbuf Destination buffer |
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* @param off Offset at which to start storing characters |
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* @param len Maximum number of characters to read |
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* |
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* @return The number of characters read, or -1 if the end of the |
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* stream has been reached |
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* |
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* @exception IOException If an I/O error occurs |
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* @exception IndexOutOfBoundsException |
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* If {@code off} is negative, or {@code len} is negative, |
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* or {@code len} is greater than {@code cbuf.length - off} |
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*/ |
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public abstract int read(char cbuf[], int off, int len) throws IOException; |
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/** Maximum skip-buffer size */ |
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private static final int maxSkipBufferSize = 8192; |
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/** Skip buffer, null until allocated */ |
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private char skipBuffer[] = null; |
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/** |
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* Skips characters. This method will block until some characters are |
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* available, an I/O error occurs, or the end of the stream is reached. |
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* |
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* @param n The number of characters to skip |
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* |
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* @return The number of characters actually skipped |
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* |
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* @exception IllegalArgumentException If <code>n</code> is negative. |
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* @exception IOException If an I/O error occurs |
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*/ |
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public long skip(long n) throws IOException { |
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if (n < 0L) |
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throw new IllegalArgumentException("skip value is negative"); |
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int nn = (int) Math.min(n, maxSkipBufferSize); |
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synchronized (lock) { |
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if ((skipBuffer == null) || (skipBuffer.length < nn)) |
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skipBuffer = new char[nn]; |
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long r = n; |
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while (r > 0) { |
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int nc = read(skipBuffer, 0, (int)Math.min(r, nn)); |
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if (nc == -1) |
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break; |
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r -= nc; |
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} |
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return n - r; |
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} |
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} |
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/** |
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* Tells whether this stream is ready to be read. |
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* |
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* @return True if the next read() is guaranteed not to block for input, |
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* false otherwise. Note that returning false does not guarantee that the |
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* next read will block. |
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* |
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* @exception IOException If an I/O error occurs |
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*/ |
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public boolean ready() throws IOException { |
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return false; |
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} |
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/** |
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* Tells whether this stream supports the mark() operation. The default |
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* implementation always returns false. Subclasses should override this |
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* method. |
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* |
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* @return true if and only if this stream supports the mark operation. |
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*/ |
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public boolean markSupported() { |
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return false; |
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} |
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/** |
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* Marks the present position in the stream. Subsequent calls to reset() |
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* will attempt to reposition the stream to this point. Not all |
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* character-input streams support the mark() operation. |
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* |
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* @param readAheadLimit Limit on the number of characters that may be |
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* read while still preserving the mark. After |
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* reading this many characters, attempting to |
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* reset the stream may fail. |
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* |
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* @exception IOException If the stream does not support mark(), |
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* or if some other I/O error occurs |
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*/ |
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public void mark(int readAheadLimit) throws IOException { |
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throw new IOException("mark() not supported"); |
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} |
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/** |
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* Resets the stream. If the stream has been marked, then attempt to |
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* reposition it at the mark. If the stream has not been marked, then |
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* attempt to reset it in some way appropriate to the particular stream, |
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* for example by repositioning it to its starting point. Not all |
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* character-input streams support the reset() operation, and some support |
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* reset() without supporting mark(). |
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* |
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* @exception IOException If the stream has not been marked, |
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* or if the mark has been invalidated, |
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* or if the stream does not support reset(), |
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* or if some other I/O error occurs |
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*/ |
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public void reset() throws IOException { |
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throw new IOException("reset() not supported"); |
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} |
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/** |
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* Closes the stream and releases any system resources associated with |
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* it. Once the stream has been closed, further read(), ready(), |
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* mark(), reset(), or skip() invocations will throw an IOException. |
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* Closing a previously closed stream has no effect. |
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* |
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* @exception IOException If an I/O error occurs |
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*/ |
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32649
2ee9017c7597
8136583: Core libraries should use blessed modifier order
martin
parents:
32033
diff
changeset
|
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public abstract void close() throws IOException; |
2 | 348 |
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/** |
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* Reads all characters from this reader and writes the characters to the |
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* given writer in the order that they are read. On return, this reader |
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* will be at end of the stream. This method does not close either reader |
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* or writer. |
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* <p> |
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* This method may block indefinitely reading from the reader, or |
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* writing to the writer. The behavior for the case where the reader |
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* and/or writer is <i>asynchronously closed</i>, or the thread |
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* interrupted during the transfer, is highly reader and writer |
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* specific, and therefore not specified. |
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* <p> |
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* If an I/O error occurs reading from the reader or writing to the |
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* writer, then it may do so after some characters have been read or |
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* written. Consequently the reader may not be at end of the stream and |
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* one, or both, streams may be in an inconsistent state. It is strongly |
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* recommended that both streams be promptly closed if an I/O error occurs. |
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* |
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* @param out the writer, non-null |
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* @return the number of characters transferred |
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* @throws IOException if an I/O error occurs when reading or writing |
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* @throws NullPointerException if {@code out} is {@code null} |
|
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* |
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* @since 10 |
|
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*/ |
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374 |
public long transferTo(Writer out) throws IOException { |
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Objects.requireNonNull(out, "out"); |
|
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long transferred = 0; |
|
377 |
char[] buffer = new char[TRANSFER_BUFFER_SIZE]; |
|
378 |
int nRead; |
|
379 |
while ((nRead = read(buffer, 0, TRANSFER_BUFFER_SIZE)) >= 0) { |
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out.write(buffer, 0, nRead); |
|
381 |
transferred += nRead; |
|
382 |
} |
|
383 |
return transferred; |
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384 |
} |
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2 | 386 |
} |