org.jspare.server.transaction.TidGeneratorImpl.java Source code

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Here is the source code for org.jspare.server.transaction.TidGeneratorImpl.java

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/*
 * Copyright 2016 JSpare.org.
 *
 * 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 org.jspare.server.transaction;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.ChronoField;
import java.util.concurrent.ThreadLocalRandom;

import org.apache.commons.lang.StringUtils;

/**
 * The Class TidGeneratorImpl.
 *
 * @author pflima
 * @since 30/03/2016
 */
public class TidGeneratorImpl implements TidGenerator {

    /** The Constant TIMESTAMP_FORMAT. */
    private static final String TIMESTAMP_FORMAT = "yyyyMMddHHmmss";

    /** The Constant MILLI_OF_SECOND. */
    private static final int MILLI_OF_SECOND = 3;

    /** The Constant MIN. */
    private static final long MIN = 100000l;

    /** The Constant MAX. */
    private static final long MAX = 989898l;

    /** The dtf. */
    private DateTimeFormatter dtf = new DateTimeFormatterBuilder().appendPattern(TIMESTAMP_FORMAT)
            .appendValue(ChronoField.MILLI_OF_SECOND, MILLI_OF_SECOND).toFormatter();

    /*
     * (non-Javadoc)
     *
     * @see org.jspare.server.transaction.TidGenerator#generate()
     */
    @Override
    public String generate() {

        StringBuilder tid = new StringBuilder();
        tid.append(LocalDateTime.now().format(dtf));
        tid.append(StringUtils.leftPad(String.valueOf(ThreadLocalRandom.current().nextLong(MIN, MAX)), 6, "0"));
        tid.append(calculateVerifyDigit(tid.toString()));
        return tid.toString();
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.jspare.server.transaction.TidGenerator#validate(java.lang.String)
     */
    @Override
    public boolean validate(final String tid) {

        try {
            if (StringUtils.isEmpty(tid)) {
                return false;
            }

            String prefix = tid.substring(0, TIMESTAMP_FORMAT.length() + MILLI_OF_SECOND);
            if (!LocalDateTime.parse(prefix, dtf).isBefore(LocalDateTime.now())) {
                return false;
            }

            long sufix = Long
                    .parseLong(tid.substring(TIMESTAMP_FORMAT.length() + MILLI_OF_SECOND, tid.length() - 1));
            if (sufix <= MIN || sufix >= MAX) {
                return false;
            }
            int verifyDigit = Integer.parseInt(String.valueOf(tid.charAt(tid.length() - 1)));

            return validateVerifyDigit(tid, verifyDigit);

        } catch (Exception e) {

            return false;
        }
    }

    /**
     * Calculate verify digit.
     *
     * @param preTid
     *            the pre tid
     * @return the int
     */
    private int calculateVerifyDigit(final String preTid) {

        int calc = 0;
        for (int i = 0, n = preTid.length(); i < n; i++) {
            if (i % 2 != 0) {
                calc += preTid.charAt(i);
            }
        }
        calc *= 3;
        for (int p = 0, n = preTid.length(); p < n; p++) {
            if (p % 2 == 0) {
                calc += preTid.charAt(p);
            }
        }

        int d = 0;
        while (((calc + d) % 10) != 0) {
            d++;
        }
        return d;
    }

    /**
     * Validate verify digit.
     *
     * @param tid
     *            the tid
     * @param verifyDigit
     *            the verify digit
     * @return true, if successful
     */
    private boolean validateVerifyDigit(final String tid, final int verifyDigit) {

        String preTid = tid.substring(0, tid.length() - 1);
        return calculateVerifyDigit(preTid) == verifyDigit;
    }
}