255 lines
8.2 KiB
Java
255 lines
8.2 KiB
Java
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/*
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* Copyright (c) 1996, 2019, 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.nio.charset.Charset;
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import java.nio.charset.CharsetEncoder;
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import sun.nio.cs.StreamEncoder;
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/**
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* An OutputStreamWriter is a bridge from character streams to byte streams:
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* Characters written to it are encoded into bytes using a specified {@link
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* java.nio.charset.Charset charset}. The charset that it uses
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* may be specified by name or may be given explicitly, or the platform's
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* default charset may be accepted.
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*
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* <p> Each invocation of a write() method causes the encoding converter to be
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* invoked on the given character(s). The resulting bytes are accumulated in a
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* buffer before being written to the underlying output stream. Note that the
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* characters passed to the write() methods are not buffered.
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*
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* <p> For top efficiency, consider wrapping an OutputStreamWriter within a
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* BufferedWriter so as to avoid frequent converter invocations. For example:
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*
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* <pre>
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* Writer out
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* = new BufferedWriter(new OutputStreamWriter(System.out));
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* </pre>
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*
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* <p> A <i>surrogate pair</i> is a character represented by a sequence of two
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* {@code char} values: A <i>high</i> surrogate in the range '\uD800' to
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* '\uDBFF' followed by a <i>low</i> surrogate in the range '\uDC00' to
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* '\uDFFF'.
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*
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* <p> A <i>malformed surrogate element</i> is a high surrogate that is not
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* followed by a low surrogate or a low surrogate that is not preceded by a
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* high surrogate.
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*
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* <p> This class always replaces malformed surrogate elements and unmappable
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* character sequences with the charset's default <i>substitution sequence</i>.
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* The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more
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* control over the encoding process is required.
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*
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* @see BufferedWriter
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* @see OutputStream
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* @see java.nio.charset.Charset
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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 class OutputStreamWriter extends Writer {
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private final StreamEncoder se;
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/**
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* Creates an OutputStreamWriter that uses the named charset.
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*
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* @param out
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* An OutputStream
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*
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* @param charsetName
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* The name of a supported
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* {@link java.nio.charset.Charset charset}
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*
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* @throws UnsupportedEncodingException
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* If the named encoding is not supported
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*/
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public OutputStreamWriter(OutputStream out, String charsetName)
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throws UnsupportedEncodingException
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{
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super(out);
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if (charsetName == null)
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throw new NullPointerException("charsetName");
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se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
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}
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/**
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* Creates an OutputStreamWriter that uses the default character encoding.
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*
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* @param out An OutputStream
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*/
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public OutputStreamWriter(OutputStream out) {
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super(out);
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se = StreamEncoder.forOutputStreamWriter(out, this,
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Charset.defaultCharset());
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}
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/**
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* Creates an OutputStreamWriter that uses the given charset.
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*
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* @param out
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* An OutputStream
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*
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* @param cs
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* A charset
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*
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* @since 1.4
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*/
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public OutputStreamWriter(OutputStream out, Charset cs) {
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super(out);
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if (cs == null)
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throw new NullPointerException("charset");
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se = StreamEncoder.forOutputStreamWriter(out, this, cs);
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}
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/**
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* Creates an OutputStreamWriter that uses the given charset encoder.
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*
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* @param out
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* An OutputStream
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*
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* @param enc
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* A charset encoder
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*
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* @since 1.4
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*/
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public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {
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super(out);
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if (enc == null)
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throw new NullPointerException("charset encoder");
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se = StreamEncoder.forOutputStreamWriter(out, this, enc);
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}
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/**
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* Returns the name of the character encoding being used by this stream.
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*
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* <p> If the encoding has an historical name then that name is returned;
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* otherwise the encoding's canonical name is returned.
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*
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* <p> If this instance was created with the {@link
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* #OutputStreamWriter(OutputStream, String)} constructor then the returned
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* name, being unique for the encoding, may differ from the name passed to
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* the constructor. This method may return {@code null} if the stream has
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* been closed. </p>
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*
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* @return The historical name of this encoding, or possibly
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* {@code null} if the stream has been closed
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*
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* @see java.nio.charset.Charset
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*
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* @revised 1.4
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*/
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public String getEncoding() {
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return se.getEncoding();
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}
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/**
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* Flushes the output buffer to the underlying byte stream, without flushing
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* the byte stream itself. This method is non-private only so that it may
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* be invoked by PrintStream.
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*/
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void flushBuffer() throws IOException {
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se.flushBuffer();
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}
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/**
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* Writes a single character.
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*
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* @throws IOException If an I/O error occurs
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*/
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public void write(int c) throws IOException {
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se.write(c);
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}
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/**
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* Writes a portion of an array of characters.
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*
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* @param cbuf Buffer of characters
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* @param off Offset from which to start writing characters
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* @param len Number of characters to write
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*
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* @throws IndexOutOfBoundsException
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* If {@code off} is negative, or {@code len} is negative,
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* or {@code off + len} is negative or greater than the length
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* of the given array
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*
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* @throws IOException If an I/O error occurs
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*/
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public void write(char cbuf[], int off, int len) throws IOException {
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se.write(cbuf, off, len);
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}
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/**
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* Writes a portion of a string.
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*
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* @param str A String
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* @param off Offset from which to start writing characters
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* @param len Number of characters to write
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*
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* @throws IndexOutOfBoundsException
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* If {@code off} is negative, or {@code len} is negative,
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* or {@code off + len} is negative or greater than the length
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* of the given string
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*
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* @throws IOException If an I/O error occurs
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*/
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public void write(String str, int off, int len) throws IOException {
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se.write(str, off, len);
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}
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@Override
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public Writer append(CharSequence csq, int start, int end) throws IOException {
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if (csq == null) csq = "null";
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return append(csq.subSequence(start, end));
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}
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@Override
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public Writer append(CharSequence csq) throws IOException {
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if (csq instanceof CharBuffer) {
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se.write((CharBuffer) csq);
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} else {
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se.write(String.valueOf(csq));
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}
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return this;
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}
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/**
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* Flushes the stream.
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*
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* @throws IOException If an I/O error occurs
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*/
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public void flush() throws IOException {
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se.flush();
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}
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public void close() throws IOException {
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se.close();
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}
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}
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