com.thelastcheck.commons.buffer.AsciiToEbcdicByteArrayConverter Maven / Gradle / Ivy

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The buffer management utilities used for managing streams of bytes that need to be treated as structured data. These are typically used to map structured records in files to and from systems that use these files types, i.e. IBM mainframe systems.

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/* 
 *  Copyright 2009 The Last Check, LLC, All Rights Reserved
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0 
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package com.thelastcheck.commons.buffer;

import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;

import org.slf4j.LoggerFactory;


/**
 * @author Jerry Bowman
 * @copyright (c) 2009, The Last Check, All Rights Reserved.
 * @cvs $Date: 2010/11/15 17:42:05 $ $Revision: 1.3 $
 */

public class AsciiToEbcdicByteArrayConverter extends ByteArrayConverter {

    private static final String EBCDIC               = ByteArray.EBCDIC_CHARSET_NAME;

    private static byte[]       convertToEbcdicTable = null;

    public AsciiToEbcdicByteArrayConverter() {
        super();
    }

    /**
     * @return a byte array containing the conversion for ASCII to EBCDIC
     * @throws UnsupportedEncodingException
     */
    protected byte[] loadConvertTable() throws UnsupportedEncodingException {
        synchronized (AsciiToEbcdicByteArrayConverter.class) {
            loadConvertTableSynch();
        }
        return convertToEbcdicTable;
    }

    private void loadConvertTableSynch() {
        if (convertToEbcdicTable != null) {
            return;
        }

        Charset csEbcdic = Charset.forName(EBCDIC);

        char[] charsAscii = new char[256];
        for (int i = 0; i < charsAscii.length; i++) {
            charsAscii[i] = (char) i;
        }

        CharBuffer cbAscii = CharBuffer.wrap(charsAscii);

        /*
         * This create an array of bytes that can be indexed using an ASCII
         * value to get the corresponding EBCDIC value. For example:
         * 
         * byte ascii = (byte) '*'; 
         * byte ebcdic = convertToEbcdicTable[ascii & 0x00ff];
         */
        ByteBuffer bbEbcdic = csEbcdic.encode(cbAscii);
        convertToEbcdicTable = new byte[256];
        bbEbcdic.get(convertToEbcdicTable);
        for (int i = 128; i < convertToEbcdicTable.length; i++) {
            convertToEbcdicTable[i] = 0x6f;
        }
    }

    @Override
    protected String outputEncoding() {
        return EBCDIC;
    }

}