UTF8ByteBufferWriter.java

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/*
 * Javolution - Java(TM) Solution for Real-Time and Embedded Systems
 * Copyright (C) 2012 - Javolution (http://javolution.org/)
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software is
 * freely granted, provided that this notice is preserved.
 */
package javolution.io;
 
import java.io.CharConversionException;
import java.io.IOException;
import java.io.Writer;
import java.nio.ByteBuffer;
 
public final class UTF8ByteBufferWriter extends Writer {
 
    private ByteBuffer _byteBuffer;
 
    public UTF8ByteBufferWriter() {}
 
    public UTF8ByteBufferWriter setOutput(ByteBuffer byteBuffer) {
        if (_byteBuffer != null)
            throw new IllegalStateException("Writer not closed or reset");
        _byteBuffer = byteBuffer;
        return this;
    }
 
    public void write(char c) throws IOException {
        if ((c < 0xd800) || (c > 0xdfff)) {
            write((int) c);
        } else if (c < 0xdc00) { // High surrogate.
            _highSurrogate = c;
        } else { // Low surrogate.
            int code = ((_highSurrogate - 0xd800) << 10) + (c - 0xdc00)
                    + 0x10000;
            write(code);
        }
    }
 
    private char _highSurrogate;
 
    public void write(int code) throws IOException {
        if ((code & 0xffffff80) == 0) {
            _byteBuffer.put((byte) code);
        } else { // Writes more than one byte.
            write2(code);
        }
    }
 
    private void write2(int c) throws IOException {
        if ((c & 0xfffff800) == 0) { // 2 bytes.
            _byteBuffer.put((byte) (0xc0 | (c >> 6)));
            _byteBuffer.put((byte) (0x80 | (c & 0x3f)));
        } else if ((c & 0xffff0000) == 0) { // 3 bytes.
            _byteBuffer.put((byte) (0xe0 | (c >> 12)));
            _byteBuffer.put((byte) (0x80 | ((c >> 6) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | (c & 0x3f)));
        } else if ((c & 0xff200000) == 0) { // 4 bytes.
            _byteBuffer.put((byte) (0xf0 | (c >> 18)));
            _byteBuffer.put((byte) (0x80 | ((c >> 12) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | ((c >> 6) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | (c & 0x3f)));
        } else if ((c & 0xf4000000) == 0) { // 5 bytes.
            _byteBuffer.put((byte) (0xf8 | (c >> 24)));
            _byteBuffer.put((byte) (0x80 | ((c >> 18) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | ((c >> 12) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | ((c >> 6) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | (c & 0x3f)));
        } else if ((c & 0x80000000) == 0) { // 6 bytes.
            _byteBuffer.put((byte) (0xfc | (c >> 30)));
            _byteBuffer.put((byte) (0x80 | ((c >> 24) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | ((c >> 18) & 0x3f)));
            _byteBuffer.put((byte) (0x80 | ((c >> 12) & 0x3F)));
            _byteBuffer.put((byte) (0x80 | ((c >> 6) & 0x3F)));
            _byteBuffer.put((byte) (0x80 | (c & 0x3F)));
        } else {
            throw new CharConversionException("Illegal character U+"
                    + Integer.toHexString(c));
        }
    }
 
    public void write(char cbuf[], int off, int len) throws IOException {
        final int off_plus_len = off + len;
        for (int i = off; i < off_plus_len;) {
            char c = cbuf[i++];
            if (c < 0x80) {
                _byteBuffer.put((byte) c);
            } else {
                write(c);
            }
        }
    }
 
    public void write(String str, int off, int len) throws IOException {
        final int off_plus_len = off + len;
        for (int i = off; i < off_plus_len;) {
            char c = str.charAt(i++);
            if (c < 0x80) {
                _byteBuffer.put((byte) c);
            } else {
                write(c);
            }
        }
    }
 
    public void write(CharSequence csq) throws IOException {
        final int length = csq.length();
        for (int i = 0; i < length;) {
            char c = csq.charAt(i++);
            if (c < 0x80) {
                _byteBuffer.put((byte) c);
            } else {
                write(c);
            }
        }
    }
 
    public void flush() throws IOException {
        if (_byteBuffer == null) { throw new IOException("Writer closed"); }
    }
 
    public void close() throws IOException {
        if (_byteBuffer != null) {
            reset();
        }
    }
 
    // Implements Reusable.
    public void reset() {
        _byteBuffer = null;
        _highSurrogate = 0;
    }
 
    public UTF8ByteBufferWriter setByteBuffer(ByteBuffer byteBuffer) {
        return this.setOutput(byteBuffer);
    }
 
}