zkoss/zk

/* WriterOutputStream.java

    Purpose:
        
    Description:
        
    History:
        Mon May  1 22:00:51     2006, Created by tomyeh

Copyright (C) 2006 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.io;

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

/**
 * An output stream that is on top of a writer.
 *
 * @author tomyeh
 */
public class WriterOutputStream extends OutputStream {
    private final Writer _writer;
    private final String _charset;
    private final byte[] _bs; //used only with writer
    private int _cnt, _type; //used only with writer

    /** Constructs an out stream with the specified encoding.
     *
     * @param charset the charset. If null, "UTF-8" is assumed.
     */
    public WriterOutputStream(Writer writer, String charset) {
        if (writer == null) throw new IllegalArgumentException("null");
        _writer = writer;
        _bs = new byte[3];
        _charset = charset == null ? "UTF-8": charset;
    }
    /** Constructs an output stream assuming UTF-8 encoding.
     */
    public WriterOutputStream(Writer writer) {
        this(writer, null);
    }
    public void write(byte[] b) throws IOException {
        _writer.write(new String(b, _charset));
    }
    public void write(byte[] b, int off, int len) throws IOException {
        _writer.write(new String(b, 0, b.length, _charset));
    }
    public void write(int b) throws IOException {
        if (_type != 0) {
            if (!"UTF-8".equals(_charset) || (b & 0xc0) == 0x80) {
                _bs[_cnt ++] = (byte)b;
                if (_cnt == _type) { //complete
                    _writer.write(new String(_bs, 0, _type, _charset));
                    _type = 0; //reset
                }
                return;
            } else { //failed
                for (int j = 0; j < _cnt; ++j)
                    _writer.write(_bs[j]);
                _type = 0; //reset
            }
        } else {
            if ("UTF-8".equals(_charset)) {
                if ((b & 0xe0) == 0xc0 || (b & 0xf0) == 0xe0) {
                    _type = (b & 0xf0) == 0xe0 ? 3: 2;
                    _bs[0] = (byte)b;
                    _cnt = 1;
                    return;
                }
            } else {
                //assume two-bytes per char if 0x80 -- might fail.
                if ((b & 0x80) != 0) {
                    _type = 2;
                    _bs[0] = (byte)b;
                    _cnt = 1;
                    return;
                }
            }
        }
        _writer.write(b);
    }
    public void flush() throws IOException {
        if (_type != 0) {
            for (int j = 0; j < _cnt; ++j)
                _writer.write(_bs[j]); //reset
            _type = 0;
        }
        _writer.flush();
        super.flush();
    }
    public void close() throws IOException {
        flush();
        _writer.close();
        super.close();
    }
}