348 lines
10 KiB
Java
348 lines
10 KiB
Java
/* OutputStreamWriter.java -- Writer that converts chars to bytes
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Copyright (C) 1998, 1999, 2000, 2001, 2003, 2005, 2006 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.gcj.convert.UnicodeToBytes;
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import gnu.gcj.convert.CharsetToBytesAdaptor;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetEncoder;
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/**
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* This class writes characters to an output stream that is byte oriented
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* It converts the chars that are written to bytes using an encoding layer,
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* which is specific to a particular encoding standard. The desired
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* encoding can either be specified by name, or if no encoding is specified,
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* the system default encoding will be used. The system default encoding
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* name is determined from the system property <code>file.encoding</code>.
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* The only encodings that are guaranteed to be available are "8859_1"
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* (the Latin-1 character set) and "UTF8". Unfortunately, Java does not
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* provide a mechanism for listing the encodings that are supported in
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* 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)
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* <li>8859_2 (ISO-8859-2/Latin-2)
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* <li>8859_3 (ISO-8859-3/Latin-3)
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* <li>8859_4 (ISO-8859-4/Latin-4)
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* <li>8859_5 (ISO-8859-5/Latin-5)
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* <li>8859_6 (ISO-8859-6/Latin-6)
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* <li>8859_7 (ISO-8859-7/Latin-7)
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* <li>8859_8 (ISO-8859-8/Latin-8)
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* <li>8859_9 (ISO-8859-9/Latin-9)
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* <li>ASCII (7-bit ASCII)
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* <li>UTF8 (UCS Transformation Format-8)
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* <li>More Later
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* </ul>
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*
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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 17, 1998.
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*/
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public class OutputStreamWriter extends Writer
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{
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BufferedOutputStream out;
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/**
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* This is the byte-character encoder class that does the writing and
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* translation of characters to bytes before writing to the underlying
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* class.
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*/
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UnicodeToBytes converter;
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/* Temporary buffer. */
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private char[] work;
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private int wcount;
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private OutputStreamWriter(OutputStream out, UnicodeToBytes encoder)
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{
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this.out = out instanceof BufferedOutputStream
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? (BufferedOutputStream) out
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: new BufferedOutputStream(out, 250);
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/* Don't need to call super(out) here as long as the lock gets set. */
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this.lock = out;
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this.converter = encoder;
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}
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/**
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* This method initializes a new instance of <code>OutputStreamWriter</code>
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* to write to 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 out The <code>OutputStream</code> to write to
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* @param encoding_scheme The name of the encoding scheme to use for
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* character to byte translation
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*
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* @exception UnsupportedEncodingException If the named encoding is
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* not available.
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*/
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public OutputStreamWriter (OutputStream out, String encoding_scheme)
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throws UnsupportedEncodingException
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{
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this(out, UnicodeToBytes.getEncoder(encoding_scheme));
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}
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/**
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* This method initializes a new instance of <code>OutputStreamWriter</code>
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* to write to the specified stream using the default encoding.
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*
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* @param out The <code>OutputStream</code> to write to
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*/
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public OutputStreamWriter (OutputStream out)
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{
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this(out, UnicodeToBytes.getDefaultEncoder());
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}
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/**
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* This method initializes a new instance of <code>OutputStreamWriter</code>
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* to write to the specified stream using a given <code>Charset</code>.
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*
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* @param out The <code>OutputStream</code> to write to
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* @param cs The <code>Charset</code> of the encoding to use
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*/
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public OutputStreamWriter(OutputStream out, Charset cs)
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{
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this(out, new CharsetToBytesAdaptor(cs));
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}
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/**
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* This method initializes a new instance of <code>OutputStreamWriter</code>
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* to write to the specified stream using a given
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* <code>CharsetEncoder</code>.
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*
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* @param out The <code>OutputStream</code> to write to
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* @param enc The <code>CharsetEncoder</code> to encode the output with
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*/
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public OutputStreamWriter(OutputStream out, CharsetEncoder enc)
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{
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this(out, new CharsetToBytesAdaptor(enc));
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}
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/**
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* This method closes this stream, and the underlying
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* <code>OutputStream</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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if (out != null)
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{
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converter.setFinished();
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flush();
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out.close();
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out = null;
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}
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work = null;
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}
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}
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/**
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* This method returns the name of the character encoding scheme currently
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* in use by this stream. If the stream has been closed, then this method
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* may return <code>null</code>.
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*
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* @return The encoding scheme name
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*/
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public String getEncoding ()
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{
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return out != null ? converter.getName() : null;
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}
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/**
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* This method flushes any buffered bytes to the underlying output sink.
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*
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* @exception IOException If an error occurs
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*/
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public void flush () throws IOException
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{
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synchronized (lock)
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{
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if (out == null)
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throw new IOException("Stream closed");
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// Always write -- if we are close()ing then we want to make
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// sure the converter is flushed.
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if (work == null)
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work = new char[100];
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writeChars(work, 0, wcount);
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wcount = 0;
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out.flush();
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}
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}
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/**
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* This method writes <code>count</code> characters from the specified
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* array to the output stream starting at position <code>offset</code>
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* into the array.
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*
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* @param buf The array of character to write from
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* @param offset The offset into the array to start writing chars from
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* @param count The number of chars to write.
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*
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* @exception IOException If an error occurs
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*/
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public void write (char[] buf, int offset, int count) throws IOException
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{
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synchronized (lock)
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{
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if (out == null)
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throw new IOException("Stream closed");
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if (wcount > 0)
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{
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writeChars(work, 0, wcount);
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wcount = 0;
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}
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writeChars(buf, offset, count);
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}
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}
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/*
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* Writes characters through to the inferior BufferedOutputStream.
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* Ignores wcount and the work buffer.
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*/
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private void writeChars(char[] buf, int offset, int count)
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throws IOException
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{
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do
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{
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// We must flush if out.count == out.buf.length.
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// It is probably a good idea to flush if out.buf is almost full.
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// This test is an approximation for "almost full".
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if (out.count + count >= out.buf.length)
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{
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out.flush();
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if (out.count != 0)
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throw new IOException("unable to flush output byte buffer");
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}
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converter.setOutput(out.buf, out.count);
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int converted = converter.write(buf, offset, count);
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// Must set this before we flush the output stream, because
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// flushing will reset 'out.count'.
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out.count = converter.count;
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// Flush if we cannot make progress.
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if (converted == 0 && out.count == converter.count)
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{
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out.flush();
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if (out.count != 0)
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throw new IOException("unable to flush output byte buffer");
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}
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offset += converted;
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count -= converted;
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}
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while (count > 0 || converter.havePendingBytes());
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}
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/**
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* This method writes <code>count</code> bytes from the specified
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* <code>String</code> starting at position <code>offset</code> into the
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* <code>String</code>.
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*
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* @param str The <code>String</code> to write chars from
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* @param offset The position in the <code>String</code> to start
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* writing chars from
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* @param count The number of chars to write
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*
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* @exception IOException If an error occurs
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*/
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public void write (String str, int offset, int count) throws IOException
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{
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synchronized (lock)
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{
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if (out == null)
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throw new IOException("Stream closed");
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if (work == null)
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work = new char[100];
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int wlength = work.length;
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while (count > 0)
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{
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int size = count;
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if (wcount + size > wlength)
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{
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if (2*wcount > wlength)
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{
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writeChars(work, 0, wcount);
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wcount = 0;
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}
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if (wcount + size > wlength)
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size = wlength - wcount;
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}
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str.getChars(offset, offset+size, work, wcount);
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offset += size;
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count -= size;
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wcount += size;
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}
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}
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}
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/**
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* This method writes a single character to the output stream.
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*
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* @param ch The char to write, passed as an int.
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*
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* @exception IOException If an error occurs
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*/
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public void write (int ch) throws IOException
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{
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synchronized (lock)
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{
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if (out == null)
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throw new IOException("Stream closed");
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if (work == null)
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work = new char[100];
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if (wcount >= work.length)
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{
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writeChars(work, 0, wcount);
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wcount = 0;
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}
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work[wcount++] = (char) ch;
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}
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}
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} // class OutputStreamWriter
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