DateTimeParser.java

/*
 * Copyright 2013 David Tinker
 *
 * 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 io.qdb.server.databind;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

/**
 * Date time parser that accepts several formats. Thread safe.
 */
public class DateTimeParser {

    private final SimpleDateFormat millis = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
    private final SimpleDateFormat millisNoTz = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS");
    private final SimpleDateFormat full = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
    private final SimpleDateFormat noTz = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
    private final SimpleDateFormat noSecs = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm");
    private final SimpleDateFormat dateOnly = new SimpleDateFormat("yyyy-MM-dd");
    private final SimpleDateFormat secs = new SimpleDateFormat("HH:mm:ss");
    private final SimpleDateFormat mins = new SimpleDateFormat("HH:mm");

    public static final DateTimeParser INSTANCE = new DateTimeParser();

    public Date parse(String s) throws ParseException {
        Date ans;
        if (isAllDigits(s)) {
            try {
                return new Date(Long.parseLong(s));
            } catch (NumberFormatException e) {
                throw new ParseException(e.getMessage(), 0);
            }
        }
        int n = s.length();
        switch (n) {
            case 5:
                synchronized (mins) { ans = mins.parse(s); }
                timeToToday(ans);
                break;
            case 8:
                synchronized (secs) { ans = secs.parse(s); }
                timeToToday(ans);
                break;
            case 10:
                synchronized (dateOnly) { ans = dateOnly.parse(s); }
                break;
            case 16:
                synchronized (noSecs) { ans = noSecs.parse(s); }
                break;
            case 19:
                synchronized (noTz) { ans = noTz.parse(s); }
                break;
            default:
                if (s.lastIndexOf('.') > 0) {
                    if (n > 23) {
                        synchronized (millis) { ans = millis.parse(s.replace(' ', '+')); }
                    }
                    else synchronized (millisNoTz) { ans = millisNoTz.parse(s); }
                } else {
                    synchronized (full) { ans = full.parse(s.replace(' ', '+')); }
                }
        }
        return ans;
    }

    private boolean isAllDigits(String s) {
        for (int i = s.length() - 1; i >= 0; i--) {
            char c = s.charAt(i);
            if (c < '0' || c > '9') return false;
        }
        return true;
    }

    @SuppressWarnings("deprecation")
    private void timeToToday(Date d) {
        GregorianCalendar gc = new GregorianCalendar();
        d.setYear(gc.get(Calendar.YEAR) - 1900);
        d.setMonth(gc.get(Calendar.MONTH));
        d.setDate(gc.get(Calendar.DAY_OF_MONTH));
    }

    /**
     * Format date with milliseconds and timezone.
     */
    public String formatTimestamp(Date date) {
        return millis.format(date);
    }
}