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jlechner |
/* InputStreamReader.java -- Reader than transforms bytes to chars
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Copyright (C) 1998, 1999, 2001, 2003, 2004, 2005 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.io;
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import gnu.java.nio.charset.EncodingHelper;
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import java.nio.ByteBuffer;
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import java.nio.CharBuffer;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetDecoder;
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import java.nio.charset.CoderResult;
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import java.nio.charset.CodingErrorAction;
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/**
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* This class reads characters from a byte input stream. The characters
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* read are converted from bytes in the underlying stream by a
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* decoding layer. The decoding layer transforms bytes to chars according
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* to an encoding standard. There are many available encodings to choose
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* from. The desired encoding can either be specified by name, or if no
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* encoding is selected, the system default encoding will be used. The
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* system default encoding name is determined from the system property
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* <code>file.encoding</code>. The only encodings that are guaranteed to
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* be availalbe are "8859_1" (the Latin-1 character set) and "UTF8".
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* Unforunately, Java does not provide a mechanism for listing the
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* ecodings that are supported in a given implementation.
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* <p>
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* Here is a list of standard encoding names that may be available:
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* <p>
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* <ul>
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* <li>8859_1 (ISO-8859-1/Latin-1)</li>
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* <li>8859_2 (ISO-8859-2/Latin-2)</li>
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* <li>8859_3 (ISO-8859-3/Latin-3)</li>
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* <li>8859_4 (ISO-8859-4/Latin-4)</li>
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* <li>8859_5 (ISO-8859-5/Latin-5)</li>
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* <li>8859_6 (ISO-8859-6/Latin-6)</li>
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* <li>8859_7 (ISO-8859-7/Latin-7)</li>
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* <li>8859_8 (ISO-8859-8/Latin-8)</li>
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* <li>8859_9 (ISO-8859-9/Latin-9)</li>
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* <li>ASCII (7-bit ASCII)</li>
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* <li>UTF8 (UCS Transformation Format-8)</li>
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* <li>More later</li>
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* </ul>
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* <p>
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* It is recommended that applications do not use
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* <code>InputStreamReader</code>'s
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* directly. Rather, for efficiency purposes, an object of this class
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* should be wrapped by a <code>BufferedReader</code>.
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* <p>
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* Due to a deficiency the Java class library design, there is no standard
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* way for an application to install its own byte-character encoding.
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*
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* @see BufferedReader
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* @see InputStream
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*
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* @author Robert Schuster
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Per Bothner (bothner@cygnus.com)
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* @date April 22, 1998.
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*/
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public class InputStreamReader extends Reader
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{
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/**
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* The input stream.
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*/
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private InputStream in;
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/**
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* The charset decoder.
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*/
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private CharsetDecoder decoder;
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/**
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* End of stream reached.
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*/
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private boolean isDone = false;
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/**
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* Need this.
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*/
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private float maxBytesPerChar;
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/**
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* Buffer holding surplus loaded bytes (if any)
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*/
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private ByteBuffer byteBuffer;
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/**
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* java.io canonical name of the encoding.
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*/
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private String encoding;
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/**
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* We might decode to a 2-char UTF-16 surrogate, which won't fit in the
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* output buffer. In this case we need to save the surrogate char.
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*/
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private char savedSurrogate;
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private boolean hasSavedSurrogate = false;
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/**
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* This method initializes a new instance of <code>InputStreamReader</code>
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* to read from the specified stream using the default encoding.
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*
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* @param in The <code>InputStream</code> to read from
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*/
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public InputStreamReader(InputStream in)
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{
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if (in == null)
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throw new NullPointerException();
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this.in = in;
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try
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{
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encoding = System.getProperty("file.encoding");
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// Don't use NIO if avoidable
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if(EncodingHelper.isISOLatin1(encoding))
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{
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encoding = "ISO8859_1";
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maxBytesPerChar = 1f;
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decoder = null;
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return;
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}
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Charset cs = EncodingHelper.getCharset(encoding);
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decoder = cs.newDecoder();
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encoding = EncodingHelper.getOldCanonical(cs.name());
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try {
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maxBytesPerChar = cs.newEncoder().maxBytesPerChar();
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} catch(UnsupportedOperationException _){
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maxBytesPerChar = 1f;
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}
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decoder.onMalformedInput(CodingErrorAction.REPLACE);
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decoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
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decoder.reset();
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} catch(RuntimeException e) {
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encoding = "ISO8859_1";
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maxBytesPerChar = 1f;
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decoder = null;
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} catch(UnsupportedEncodingException e) {
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encoding = "ISO8859_1";
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maxBytesPerChar = 1f;
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decoder = null;
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}
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}
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/**
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* This method initializes a new instance of <code>InputStreamReader</code>
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* to read from the specified stream using a caller supplied character
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* encoding scheme. Note that due to a deficiency in the Java language
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* design, there is no way to determine which encodings are supported.
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*
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* @param in The <code>InputStream</code> to read from
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* @param encoding_name The name of the encoding scheme to use
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*
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* @exception UnsupportedEncodingException If the encoding scheme
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* requested is not available.
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*/
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public InputStreamReader(InputStream in, String encoding_name)
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throws UnsupportedEncodingException
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{
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if (in == null
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|| encoding_name == null)
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throw new NullPointerException();
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this.in = in;
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// Don't use NIO if avoidable
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if(EncodingHelper.isISOLatin1(encoding_name))
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{
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encoding = "ISO8859_1";
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maxBytesPerChar = 1f;
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decoder = null;
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return;
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}
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try {
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Charset cs = EncodingHelper.getCharset(encoding_name);
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try {
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maxBytesPerChar = cs.newEncoder().maxBytesPerChar();
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} catch(UnsupportedOperationException _){
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maxBytesPerChar = 1f;
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}
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decoder = cs.newDecoder();
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decoder.onMalformedInput(CodingErrorAction.REPLACE);
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decoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
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decoder.reset();
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// The encoding should be the old name, if such exists.
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encoding = EncodingHelper.getOldCanonical(cs.name());
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} catch(RuntimeException e) {
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encoding = "ISO8859_1";
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maxBytesPerChar = 1f;
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decoder = null;
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}
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}
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/**
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* Creates an InputStreamReader that uses a decoder of the given
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* charset to decode the bytes in the InputStream into
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* characters.
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*/
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public InputStreamReader(InputStream in, Charset charset) {
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this.in = in;
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decoder = charset.newDecoder();
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decoder.onMalformedInput(CodingErrorAction.REPLACE);
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decoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
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decoder.reset();
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encoding = EncodingHelper.getOldCanonical(charset.name());
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}
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/**
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* Creates an InputStreamReader that uses the given charset decoder
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* to decode the bytes in the InputStream into characters.
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*/
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public InputStreamReader(InputStream in, CharsetDecoder decoder) {
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this.in = in;
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this.decoder = decoder;
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Charset charset = decoder.charset();
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try {
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if (charset == null)
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maxBytesPerChar = 1f;
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else
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maxBytesPerChar = charset.newEncoder().maxBytesPerChar();
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} catch(UnsupportedOperationException _){
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maxBytesPerChar = 1f;
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}
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decoder.onMalformedInput(CodingErrorAction.REPLACE);
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decoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
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decoder.reset();
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if (charset == null)
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encoding = "US-ASCII";
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else
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encoding = EncodingHelper.getOldCanonical(decoder.charset().name());
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}
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/**
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* This method closes this stream, as well as the underlying
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* <code>InputStream</code>.
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*
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* @exception IOException If an error occurs
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*/
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public void close() throws IOException
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{
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synchronized (lock)
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{
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281 |
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// Makes sure all intermediate data is released by the decoder.
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if (decoder != null)
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decoder.reset();
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if (in != null)
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in.close();
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in = null;
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isDone = true;
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288 |
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decoder = null;
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289 |
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}
|
290 |
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}
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291 |
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|
292 |
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/**
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293 |
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* This method returns the name of the encoding that is currently in use
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* by this object. If the stream has been closed, this method is allowed
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295 |
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* to return <code>null</code>.
|
296 |
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*
|
297 |
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* @return The current encoding name
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298 |
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*/
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299 |
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public String getEncoding()
|
300 |
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{
|
301 |
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return in != null ? encoding : null;
|
302 |
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}
|
303 |
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|
304 |
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/**
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305 |
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* This method checks to see if the stream is ready to be read. It
|
306 |
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* will return <code>true</code> if is, or <code>false</code> if it is not.
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307 |
|
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* If the stream is not ready to be read, it could (although is not required
|
308 |
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* to) block on the next read attempt.
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309 |
|
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*
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310 |
|
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* @return <code>true</code> if the stream is ready to be read,
|
311 |
|
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* <code>false</code> otherwise
|
312 |
|
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*
|
313 |
|
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* @exception IOException If an error occurs
|
314 |
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*/
|
315 |
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public boolean ready() throws IOException
|
316 |
|
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{
|
317 |
|
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if (in == null)
|
318 |
|
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throw new IOException("Reader has been closed");
|
319 |
|
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|
320 |
|
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return in.available() != 0;
|
321 |
|
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}
|
322 |
|
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|
323 |
|
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/**
|
324 |
|
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* This method reads up to <code>length</code> characters from the stream into
|
325 |
|
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* the specified array starting at index <code>offset</code> into the
|
326 |
|
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* array.
|
327 |
|
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*
|
328 |
|
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* @param buf The character array to recieve the data read
|
329 |
|
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* @param offset The offset into the array to start storing characters
|
330 |
|
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* @param length The requested number of characters to read.
|
331 |
|
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*
|
332 |
|
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* @return The actual number of characters read, or -1 if end of stream.
|
333 |
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*
|
334 |
|
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* @exception IOException If an error occurs
|
335 |
|
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*/
|
336 |
|
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public int read(char[] buf, int offset, int length) throws IOException
|
337 |
|
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{
|
338 |
|
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if (in == null)
|
339 |
|
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throw new IOException("Reader has been closed");
|
340 |
|
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if (isDone)
|
341 |
|
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return -1;
|
342 |
|
|
if(decoder != null){
|
343 |
|
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int totalBytes = (int)((double)length * maxBytesPerChar);
|
344 |
|
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byte[] bytes = new byte[totalBytes];
|
345 |
|
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|
346 |
|
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int remaining = 0;
|
347 |
|
|
if(byteBuffer != null)
|
348 |
|
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{
|
349 |
|
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remaining = byteBuffer.remaining();
|
350 |
|
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byteBuffer.get(bytes, 0, remaining);
|
351 |
|
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}
|
352 |
|
|
int read;
|
353 |
|
|
if(totalBytes - remaining > 0)
|
354 |
|
|
{
|
355 |
|
|
read = in.read(bytes, remaining, totalBytes - remaining);
|
356 |
|
|
if(read == -1){
|
357 |
|
|
read = remaining;
|
358 |
|
|
isDone = true;
|
359 |
|
|
} else
|
360 |
|
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read += remaining;
|
361 |
|
|
} else
|
362 |
|
|
read = remaining;
|
363 |
|
|
byteBuffer = ByteBuffer.wrap(bytes, 0, read);
|
364 |
|
|
CharBuffer cb = CharBuffer.wrap(buf, offset, length);
|
365 |
|
|
int startPos = cb.position();
|
366 |
|
|
|
367 |
|
|
if(hasSavedSurrogate){
|
368 |
|
|
hasSavedSurrogate = false;
|
369 |
|
|
cb.put(savedSurrogate);
|
370 |
|
|
read++;
|
371 |
|
|
}
|
372 |
|
|
|
373 |
|
|
CoderResult cr = decoder.decode(byteBuffer, cb, isDone);
|
374 |
|
|
decoder.reset();
|
375 |
|
|
// 1 char remains which is the first half of a surrogate pair.
|
376 |
|
|
if(cr.isOverflow() && cb.hasRemaining()){
|
377 |
|
|
CharBuffer overflowbuf = CharBuffer.allocate(2);
|
378 |
|
|
cr = decoder.decode(byteBuffer, overflowbuf, isDone);
|
379 |
|
|
overflowbuf.flip();
|
380 |
|
|
if(overflowbuf.hasRemaining())
|
381 |
|
|
{
|
382 |
|
|
cb.put(overflowbuf.get());
|
383 |
|
|
savedSurrogate = overflowbuf.get();
|
384 |
|
|
hasSavedSurrogate = true;
|
385 |
|
|
isDone = false;
|
386 |
|
|
}
|
387 |
|
|
}
|
388 |
|
|
|
389 |
|
|
if(byteBuffer.hasRemaining()) {
|
390 |
|
|
byteBuffer.compact();
|
391 |
|
|
byteBuffer.flip();
|
392 |
|
|
isDone = false;
|
393 |
|
|
} else
|
394 |
|
|
byteBuffer = null;
|
395 |
|
|
|
396 |
|
|
read = cb.position() - startPos;
|
397 |
|
|
return (read <= 0) ? -1 : read;
|
398 |
|
|
} else {
|
399 |
|
|
byte[] bytes = new byte[length];
|
400 |
|
|
int read = in.read(bytes);
|
401 |
|
|
for(int i=0;i<read;i++)
|
402 |
|
|
buf[offset+i] = (char)(bytes[i]&0xFF);
|
403 |
|
|
return read;
|
404 |
|
|
}
|
405 |
|
|
}
|
406 |
|
|
|
407 |
|
|
/**
|
408 |
|
|
* Reads an char from the input stream and returns it
|
409 |
|
|
* as an int in the range of 0-65535. This method also will return -1 if
|
410 |
|
|
* the end of the stream has been reached.
|
411 |
|
|
* <p>
|
412 |
|
|
* This method will block until the char can be read.
|
413 |
|
|
*
|
414 |
|
|
* @return The char read or -1 if end of stream
|
415 |
|
|
*
|
416 |
|
|
* @exception IOException If an error occurs
|
417 |
|
|
*/
|
418 |
|
|
public int read() throws IOException
|
419 |
|
|
{
|
420 |
|
|
char[] buf = new char[1];
|
421 |
|
|
int count = read(buf, 0, 1);
|
422 |
|
|
return count > 0 ? buf[0] : -1;
|
423 |
|
|
}
|
424 |
|
|
|
425 |
|
|
/**
|
426 |
|
|
* Skips the specified number of chars in the stream. It
|
427 |
|
|
* returns the actual number of chars skipped, which may be less than the
|
428 |
|
|
* requested amount.
|
429 |
|
|
*
|
430 |
|
|
* @param count The requested number of chars to skip
|
431 |
|
|
*
|
432 |
|
|
* @return The actual number of chars skipped.
|
433 |
|
|
*
|
434 |
|
|
* @exception IOException If an error occurs
|
435 |
|
|
*/
|
436 |
|
|
public long skip(long count) throws IOException
|
437 |
|
|
{
|
438 |
|
|
if (in == null)
|
439 |
|
|
throw new IOException("Reader has been closed");
|
440 |
|
|
|
441 |
|
|
return super.skip(count);
|
442 |
|
|
}
|
443 |
|
|
}
|