de.wbuecke.codec.HexInput.java Source code

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Here is the source code for de.wbuecke.codec.HexInput.java

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/*
 * Copyright (C) 2014 Wolfgang Buecke
 *
 * 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 de.wbuecke.codec;

import org.apache.commons.lang3.StringUtils;

abstract class HexInput implements Input {

    protected abstract byte[] encodeBinary(String plaintext);

    protected abstract String decodeBinary(byte[] bytes);

    @Override
    public String encode(String plaintext) {
        byte[] bytes = encodeBinary(plaintext);
        if (bytes == null)
            return null;
        StringBuilder hex = new StringBuilder();
        for (int pos = 0; pos < bytes.length; pos++)
            hex.append(StringUtils.leftPad(Integer.toHexString(0x000000FF & bytes[pos]).toUpperCase(), 2, "0"));
        return hex.toString();
    }

    @Override
    public String decode(String input) {
        if (input.length() % 2 != 0 || input.length() == 0)
            return null;

        final byte[] bytes = new byte[input.length() / 2];
        for (int pos = 0; pos < input.length(); pos += 2) {
            try {
                bytes[pos / 2] = ((byte) Integer.parseInt(input.substring(pos, pos + 2), 16));
            } catch (NumberFormatException e) {
                return null;
            }
        }
        return decodeBinary(bytes);
    }
}