com.googlecode.jinahya.util.IdEncoder Maven / Gradle / Ivy

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/*
 * Copyright 2012 Jin Kwon .
 *
 * 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.googlecode.jinahya.util;


import java.util.Random;
import java.util.UUID;


/**
 * Encoder for Database IDs.
 *
 * @author Jin Kwon 
 */
public class IdEncoder {


    /**
     * .
     */
    private static final Random RANDOM = new Random();


    /**
     * Instance holder.
     */
    private static class PrivateInstanceHolder {


        /**
         * INSTANCE.
         */
        private static final IdEncoder INSTANCE = new IdEncoder();


        /**
         * PRIVATE.
         */
        private PrivateInstanceHolder() {
            super();
        }


    }


    /**
     * Encodes given decoded.
     * 
     * @param decoded the value to be encoded
     * @return the encoded value
     */
    public static String encodeUUID(final UUID decoded) {

        if (decoded == null) {
            throw new NullPointerException("null decoded");
        }

        final String encoded = encodeId(decoded.getMostSignificantBits()) + "-"
                               + encodeId(decoded.getLeastSignificantBits());
        assert IdCodec.DOUBLE_PATTERN.matcher(encoded).matches();

        return encoded;
    }


    /**
     * Encodes given
     * decoded.
     *
     * @param decoded the value to be encoded.
     *
     * @return the decoded value.
     */
    public static String encodeId(final long decoded) {
        return PrivateInstanceHolder.INSTANCE.encode(decoded);
    }


    /**
     * Encodes given
     * decoded.
     *
     * @param decoded the value to be encoded
     *
     * @return the encoded value.
     */
    public String encode(final long decoded) {

        final String encoded =
            block(decoded >>> 32) + "-" + block(decoded & 0xFFFFFFFFL);
        assert IdCodec.SINGLE_PATTERN.matcher(encoded).matches();

        return encoded;
    }


    private String block(final long decoded) {

        final StringBuilder builder = new StringBuilder(Long.toString(decoded));

        builder.append(Integer.toString(RANDOM.nextInt(9) + 1));
        builder.append(Integer.toString(RANDOM.nextInt(9) + 1));

        builder.reverse();

        return Long.toString(
            Long.parseLong(builder.toString()), Character.MAX_RADIX);
    }


}