Java example source code file (SimpleEUCDecoder.java)

This example Java source code file (SimpleEUCDecoder.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

charbuffer, charsetdecoder, coderresult, nio, simpleeucdecoder, ss2, ss3, string

The SimpleEUCDecoder.java Java example source code

/*
 * Copyright (c) 2003, 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.
 */

/*
 */

/**
 * Simple EUC-like decoder used by IBM01383 and IBM970
 * supports G1 - no support for G2 or G3
 */


import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;

abstract class SimpleEUCDecoder
    extends CharsetDecoder
{
    private final int SS2 =  0x8E;
    private final int SS3 =  0x8F;

    protected static String  mappingTableG1;
    protected static String  byteToCharTable;

    protected SimpleEUCDecoder(Charset cs) {
        super(cs, 0.5f, 1.0f);
    }

    private CoderResult decodeArrayLoop(ByteBuffer src, CharBuffer dst) {
        byte[] sa = src.array();
        int sp = src.arrayOffset() + src.position();
        int sl = src.arrayOffset() + src.limit();
        assert (sp <= sl);
        sp = (sp <= sl ? sp : sl);
        char[] da = dst.array();
        int dp = dst.arrayOffset() + dst.position();
        int dl = dst.arrayOffset() + dst.limit();
        assert (dp <= dl);
        dp = (dp <= dl ? dp : dl);

        try {
            while (sp < sl) {
                int byte1, byte2;
                int inputSize = 1;
                char outputChar = '\uFFFD';

                byte1 = sa[sp] & 0xff;

                if ( byte1 <= 0x9f ) {  // < 0x9f has its own table (G0)
                    if (byte1 == SS2 || byte1 == SS3 ) {
                        // No support provided for G2/G3 at this time.
                        return CoderResult.malformedForLength(1);
                    }
                    outputChar = byteToCharTable.charAt(byte1);
                } else if (byte1 < 0xa1 || byte1 > 0xfe) {  // invalid range?
                    return CoderResult.malformedForLength(1);
                } else {                                        // (G1)
                    if (sl - sp < 2) {
                        return CoderResult.UNDERFLOW;
                    }
                    byte2 = sa[sp + 1] & 0xff;
                    inputSize++;
                    if ( byte2 < 0xa1 || byte2 > 0xfe) {
                        return CoderResult.malformedForLength(2);
                    }
                    outputChar = mappingTableG1.charAt(((byte1 - 0xa1) * 94) + byte2 - 0xa1);
                }
                if  (outputChar == '\uFFFD') {
                    return CoderResult.unmappableForLength(inputSize);
                }
                if (dl - dp < 1)
                    return CoderResult.OVERFLOW;
                da[dp++] = outputChar;
                sp += inputSize;
            }
            return CoderResult.UNDERFLOW;
        } finally {
            src.position(sp - src.arrayOffset());
            dst.position(dp - dst.arrayOffset());
        }
    }

    private CoderResult decodeBufferLoop(ByteBuffer src, CharBuffer dst) {
        int mark = src.position();

        try {
            while (src.hasRemaining()) {
                char outputChar = '\uFFFD';
                int inputSize = 1;
                int byte1, byte2;

                byte1 = src.get() & 0xff;
                if ( byte1 <= 0x9f ) {
                    if (byte1 == SS2 || byte1 == SS3 ) {
                        return CoderResult.malformedForLength(1);
                    }
                    outputChar = byteToCharTable.charAt(byte1);
                } else if (byte1 < 0xa1 || byte1 > 0xfe) {
                    return CoderResult.malformedForLength(1);
                } else {
                    if (!src.hasRemaining()) {
                        return CoderResult.UNDERFLOW;
                    }
                    byte2 = src.get() & 0xff;
                    inputSize++;
                    if ( byte2 < 0xa1 || byte2 > 0xfe) {
                        return CoderResult.malformedForLength(2);
                    }
                    outputChar = mappingTableG1.charAt(((byte1 - 0xa1) * 94) + byte2 - 0xa1);
                }
                if (outputChar == '\uFFFD') {
                    return CoderResult.unmappableForLength(inputSize);
                }
                if (!dst.hasRemaining())
                    return CoderResult.OVERFLOW;
                    dst.put(outputChar);
                mark += inputSize;
            }
            return CoderResult.UNDERFLOW;
        } finally {
            src.position(mark);
        }
    }

    protected CoderResult decodeLoop(ByteBuffer src, CharBuffer dst) {
        if (src.hasArray() && dst.hasArray())
            return decodeArrayLoop(src, dst);
        else
            return decodeBufferLoop(src, dst);
    }
}