com.liferay.portal.kernel.io.OutputStreamWriter.java Source code

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Here is the source code for com.liferay.portal.kernel.io.OutputStreamWriter.java

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/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library 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 Lesser General Public License for more
 * details.
 */

package com.liferay.portal.kernel.io;

import com.liferay.petra.nio.CharsetEncoderUtil;
import com.liferay.petra.string.StringPool;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;

/**
 * @author Shuyang Zhou
 */
public class OutputStreamWriter extends Writer {

    public OutputStreamWriter(OutputStream outputStream) {
        this(outputStream, StringPool.DEFAULT_CHARSET_NAME, _DEFAULT_OUTPUT_BUFFER_SIZE, false);
    }

    public OutputStreamWriter(OutputStream outputStream, String charsetName) {
        this(outputStream, charsetName, _DEFAULT_OUTPUT_BUFFER_SIZE, false);
    }

    public OutputStreamWriter(OutputStream outputStream, String charsetName, boolean autoFlush) {

        this(outputStream, charsetName, _DEFAULT_OUTPUT_BUFFER_SIZE, autoFlush);
    }

    public OutputStreamWriter(OutputStream outputStream, String charsetName, int outputBufferSize) {

        this(outputStream, charsetName, outputBufferSize, false);
    }

    public OutputStreamWriter(OutputStream outputStream, String charsetName, int outputBufferSize,
            boolean autoFlush) {

        if (outputBufferSize < 4) {
            throw new IllegalArgumentException("Output buffer size " + outputBufferSize + " is less than 4");
        }

        if (charsetName == null) {
            charsetName = StringPool.DEFAULT_CHARSET_NAME;
        }

        _outputStream = outputStream;
        _charsetName = charsetName;
        _charsetEncoder = CharsetEncoderUtil.getCharsetEncoder(charsetName);
        _outputByteBuffer = ByteBuffer.allocate(outputBufferSize);
        _autoFlush = autoFlush;
    }

    @Override
    public void close() throws IOException {
        if (!_open) {
            return;
        }

        try {
            _flushEncoder();

            _flushBuffer();

            _outputStream.close();
        } finally {
            _open = false;
        }
    }

    @Override
    public void flush() throws IOException {
        _ensureOpen();

        _flushBuffer();

        _outputStream.flush();
    }

    public String getEncoding() {
        return _charsetName;
    }

    @Override
    public void write(char[] chars) throws IOException {
        _write(CharBuffer.wrap(chars, 0, chars.length));
    }

    @Override
    public void write(char[] chars, int offset, int length) throws IOException {
        _write(CharBuffer.wrap(chars, offset, length));
    }

    @Override
    public void write(int c) throws IOException {
        _inputCharBuffer.put((char) c);

        _write(_EMPTY_CHAR_BUFFER);
    }

    @Override
    public void write(String string) throws IOException {
        _write(CharBuffer.wrap(string, 0, string.length()));
    }

    @Override
    public void write(String string, int offset, int length) throws IOException {

        _write(CharBuffer.wrap(string, offset, offset + length));
    }

    private void _encodeLeftoverChar(CharBuffer inputCharBuffer, boolean endOfInput) throws IOException {

        if (_inputCharBuffer.position() == 0) {
            return;
        }

        if ((_inputCharBuffer.position() == 1) && inputCharBuffer.hasRemaining()) {

            _inputCharBuffer.put(inputCharBuffer.get());
        }

        _inputCharBuffer.flip();

        _encodeLoop(_inputCharBuffer, endOfInput);

        _inputCharBuffer.compact();
    }

    private void _encodeLoop(CharBuffer inputCharBuffer, boolean endOfInput) throws IOException {

        while (inputCharBuffer.hasRemaining()) {
            CoderResult coderResult = _charsetEncoder.encode(inputCharBuffer, _outputByteBuffer, endOfInput);

            if (coderResult.isError()) {
                coderResult.throwException();
            }

            if (coderResult.isUnderflow()) {
                if (_autoFlush) {
                    _flushBuffer();
                }

                if ((_inputCharBuffer != inputCharBuffer) && inputCharBuffer.hasRemaining()) {

                    _inputCharBuffer.put(inputCharBuffer.get());
                }

                break;
            }

            // Must be overflow, no need to check

            _flushBuffer();
        }
    }

    private void _ensureOpen() throws IOException {
        if (!_open) {
            throw new IOException("Stream closed");
        }
    }

    private void _flushBuffer() throws IOException {
        if (_outputByteBuffer.position() > 0) {
            _outputStream.write(_outputByteBuffer.array(), 0, _outputByteBuffer.position());

            _outputByteBuffer.rewind();
        }
    }

    private void _flushEncoder() throws IOException {
        _encodeLeftoverChar(_EMPTY_CHAR_BUFFER, true);

        // Ensure encoder transit to END state before flushing, in case the
        // encoder was never used and still in RESET state.

        _charsetEncoder.encode(_EMPTY_CHAR_BUFFER, _outputByteBuffer, true);

        while (true) {
            CoderResult coderResult = _charsetEncoder.flush(_outputByteBuffer);

            if (coderResult.isError()) {
                coderResult.throwException();
            }

            if (coderResult.isUnderflow()) {
                break;
            }

            // Must be overflow, no need to check

            _flushBuffer();
        }
    }

    private void _write(CharBuffer inputCharBuffer) throws IOException {
        _ensureOpen();

        _encodeLeftoverChar(inputCharBuffer, false);

        _encodeLoop(inputCharBuffer, false);
    }

    private static final int _DEFAULT_OUTPUT_BUFFER_SIZE = 8192;

    private static final CharBuffer _EMPTY_CHAR_BUFFER = CharBuffer.allocate(0);

    private final boolean _autoFlush;
    private final CharsetEncoder _charsetEncoder;
    private final String _charsetName;
    private final CharBuffer _inputCharBuffer = CharBuffer.allocate(2);
    private boolean _open = true;
    private final ByteBuffer _outputByteBuffer;
    private final OutputStream _outputStream;

}