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/*
 * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.io;

/**
 * An OutputStreamWriter is a bridge from character streams to byte streams:
 * Characters written to it are encoded into bytes using a specified {@link
 * java.nio.charset.Charset charset}.  The charset that it uses
 * may be specified by name or may be given explicitly, or the platform's
 * default charset may be accepted.
 *
 *  Each invocation of a write() method causes the encoding converter to be
 * invoked on the given character(s).  The resulting bytes are accumulated in a
 * buffer before being written to the underlying output stream.  The size of
 * this buffer may be specified, but by default it is large enough for most
 * purposes.  Note that the characters passed to the write() methods are not
 * buffered.
 *
 * 
 For top efficiency, consider wrapping an OutputStreamWriter within a
 * BufferedWriter so as to avoid frequent converter invocations.  For example:
 *
 * 
 * Writer out
 *   = new BufferedWriter(new OutputStreamWriter(System.out));
 * 
 *
 *  A surrogate pair is a character represented by a sequence of two
 * char values: A high surrogate in the range '\uD800' to
 * '\uDBFF' followed by a low surrogate in the range '\uDC00' to
 * '\uDFFF'.
 *
 * 
 A malformed surrogate element is a high surrogate that is not
 * followed by a low surrogate or a low surrogate that is not preceded by a
 * high surrogate.
 *
 *  This class always replaces malformed surrogate elements and unmappable
 * character sequences with the charset's default substitution sequence.
 * The {@linkplain java.nio.charset.CharsetEncoder} class should be used when more
 * control over the encoding process is required.
 *
 * @see BufferedWriter
 * @see OutputStream
 * @see java.nio.charset.Charset
 *
 * @author      Mark Reinhold
 * @since       JDK1.1
 */

public class OutputStreamWriter extends Writer {
    
    /**
     * Creates an OutputStreamWriter that uses the named charset.
     *
     * @param  out
     *         An OutputStream
     *
     * @param  charsetName
     *         The name of a supported
     *         {@link java.nio.charset.Charset charset}
     *
     * @exception  UnsupportedEncodingException
     *             If the named encoding is not supported
     */
    public OutputStreamWriter(OutputStream out, String charsetName)
        throws UnsupportedEncodingException
    {
        super(out);
        if (charsetName == null)
            throw new NullPointerException("charsetName");
        if (!charsetName.toUpperCase().equals("UTF-8")) {
            throw new UnsupportedEncodingException(charsetName);
        }
    }

    /**
     * Creates an OutputStreamWriter that uses the default character encoding.
     *
     * @param  out  An OutputStream
     */
    public OutputStreamWriter(OutputStream out) {
        super(out);
    }

    /**
     * Creates an OutputStreamWriter that uses the given charset. 

     *
     * @param  out
     *         An OutputStream
     *
     * @param  cs
     *         A charset
     *
     * @since 1.4
     * @spec JSR-51
     */
//    public OutputStreamWriter(OutputStream out, Charset cs) {
//        super(out);
//        if (cs == null)
//            throw new NullPointerException("charset");
//        se = StreamEncoder.forOutputStreamWriter(out, this, cs);
//    }

    /**
     * Creates an OutputStreamWriter that uses the given charset encoder.  
     *
     * @param  out
     *         An OutputStream
     *
     * @param  enc
     *         A charset encoder
     *
     * @since 1.4
     * @spec JSR-51
     */
//    public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {
//        super(out);
//        if (enc == null)
//            throw new NullPointerException("charset encoder");
//        se = StreamEncoder.forOutputStreamWriter(out, this, enc);
//    }

    /**
     * Returns the name of the character encoding being used by this stream.
     *
     *  If the encoding has an historical name then that name is returned;
     * otherwise the encoding's canonical name is returned.
     *
     * 
 If this instance was created with the {@link
     * #OutputStreamWriter(OutputStream, String)} constructor then the returned
     * name, being unique for the encoding, may differ from the name passed to
     * the constructor.  This method may return null if the stream has
     * been closed. 
     *
     * @return The historical name of this encoding, or possibly
     *         null if the stream has been closed
     *
     * @see java.nio.charset.Charset
     *
     * @revised 1.4
     * @spec JSR-51
     */
    public String getEncoding() {
        return "UTF-8";
    }

    /**
     * Flushes the output buffer to the underlying byte stream, without flushing
     * the byte stream itself.  This method is non-private only so that it may
     * be invoked by PrintStream.
     */
    void flushBuffer() throws IOException {
        out().flush();
    }

    /**
     * Writes a single character.
     *
     * @exception  IOException  If an I/O error occurs
     */
    public void write(int c) throws IOException {
        if (c <= 0x7F) {
            out().write(c);
        } else if (c <= 0x7FF) {
            out().write(0xC0 | (c >> 6));
            out().write(0x80 | (c & 0x3F));
        } else {
            out().write(0xE0 | (c >> 12));
            out().write(0x80 | ((c >> 6) & 0x3F));
            out().write(0x80 | (c & 0x3F));
        }
    }

    /**
     * Writes a portion of an array of characters.
     *
     * @param  cbuf  Buffer of characters
     * @param  off   Offset from which to start writing characters
     * @param  len   Number of characters to write
     *
     * @exception  IOException  If an I/O error occurs
     */
    public void write(char cbuf[], int off, int len) throws IOException {
        while (len-- > 0) {
            write(cbuf[off++]);
        }
    }

    /**
     * Writes a portion of a string.
     *
     * @param  str  A String
     * @param  off  Offset from which to start writing characters
     * @param  len  Number of characters to write
     *
     * @exception  IOException  If an I/O error occurs
     */
    public void write(String str, int off, int len) throws IOException {
        while (len-- > 0) {
            write(str.charAt(off++));
        }
    }

    /**
     * Flushes the stream.
     *
     * @exception  IOException  If an I/O error occurs
     */
    public void flush() throws IOException {
        out().flush();
    }

    public void close() throws IOException {
        out().close();
    }
    
    private OutputStream out() {
        return (OutputStream) lock;
    }
}