Android example source code file (HttpDateTime.java)

This example Android source code file (HttpDateTime.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

a-za-z, android, format, http_date_ansic_pattern, http_date_ansic_regexp, http_date_rfc_pattern, http_date_rfc_regexp, httpdatetime, illegalargumentexception, matcher, pattern, regex, string, text, timeofday, util

The HttpDateTime.java Android example source code

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * 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.android.internal.http;

import android.text.format.Time;

import java.util.Calendar;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Helper for parsing an HTTP date.
 */
public final class HttpDateTime {

    /*
     * Regular expression for parsing HTTP-date.
     *
     * Wdy, DD Mon YYYY HH:MM:SS GMT
     * RFC 822, updated by RFC 1123
     *
     * Weekday, DD-Mon-YY HH:MM:SS GMT
     * RFC 850, obsoleted by RFC 1036
     *
     * Wdy Mon DD HH:MM:SS YYYY
     * ANSI C's asctime() format
     *
     * with following variations
     *
     * Wdy, DD-Mon-YYYY HH:MM:SS GMT
     * Wdy, (SP)D Mon YYYY HH:MM:SS GMT
     * Wdy,DD Mon YYYY HH:MM:SS GMT
     * Wdy, DD-Mon-YY HH:MM:SS GMT
     * Wdy, DD Mon YYYY HH:MM:SS -HHMM
     * Wdy, DD Mon YYYY HH:MM:SS
     * Wdy Mon (SP)D HH:MM:SS YYYY
     * Wdy Mon DD HH:MM:SS YYYY GMT
     * 
     * HH can be H if the first digit is zero.
     * 
     * Mon can be the full name of the month.
     */
    private static final String HTTP_DATE_RFC_REGEXP =
            "([0-9]{1,2})[- ]([A-Za-z]{3,9})[- ]([0-9]{2,4})[ ]"
            + "([0-9]{1,2}:[0-9][0-9]:[0-9][0-9])";

    private static final String HTTP_DATE_ANSIC_REGEXP =
            "[ ]([A-Za-z]{3,9})[ ]+([0-9]{1,2})[ ]"
            + "([0-9]{1,2}:[0-9][0-9]:[0-9][0-9])[ ]([0-9]{2,4})";

    /**
     * The compiled version of the HTTP-date regular expressions.
     */
    private static final Pattern HTTP_DATE_RFC_PATTERN =
            Pattern.compile(HTTP_DATE_RFC_REGEXP);
    private static final Pattern HTTP_DATE_ANSIC_PATTERN =
            Pattern.compile(HTTP_DATE_ANSIC_REGEXP);

    private static class TimeOfDay {
        TimeOfDay(int h, int m, int s) {
            this.hour = h;
            this.minute = m;
            this.second = s;
        }
        
        int hour;
        int minute;
        int second;
    }

    public static long parse(String timeString)
            throws IllegalArgumentException {

        int date = 1;
        int month = Calendar.JANUARY;
        int year = 1970;
        TimeOfDay timeOfDay;

        Matcher rfcMatcher = HTTP_DATE_RFC_PATTERN.matcher(timeString);
        if (rfcMatcher.find()) {
            date = getDate(rfcMatcher.group(1));
            month = getMonth(rfcMatcher.group(2));
            year = getYear(rfcMatcher.group(3));
            timeOfDay = getTime(rfcMatcher.group(4));
        } else {
            Matcher ansicMatcher = HTTP_DATE_ANSIC_PATTERN.matcher(timeString);
            if (ansicMatcher.find()) {
                month = getMonth(ansicMatcher.group(1));
                date = getDate(ansicMatcher.group(2));
                timeOfDay = getTime(ansicMatcher.group(3));
                year = getYear(ansicMatcher.group(4));
            } else {
                throw new IllegalArgumentException();
            }
        }

        // FIXME: Y2038 BUG!
        if (year >= 2038) {
            year = 2038;
            month = Calendar.JANUARY;
            date = 1;
        }

        Time time = new Time(Time.TIMEZONE_UTC);
        time.set(timeOfDay.second, timeOfDay.minute, timeOfDay.hour, date,
                month, year);
        return time.toMillis(false /* use isDst */);
    }

    private static int getDate(String dateString) {
        if (dateString.length() == 2) {
            return (dateString.charAt(0) - '0') * 10
                    + (dateString.charAt(1) - '0');
        } else {
            return (dateString.charAt(0) - '0');
        }
    }

    /*
     * jan = 9 + 0 + 13 = 22
     * feb = 5 + 4 + 1 = 10
     * mar = 12 + 0 + 17 = 29
     * apr = 0 + 15 + 17 = 32
     * may = 12 + 0 + 24 = 36
     * jun = 9 + 20 + 13 = 42
     * jul = 9 + 20 + 11 = 40
     * aug = 0 + 20 + 6 = 26
     * sep = 18 + 4 + 15 = 37
     * oct = 14 + 2 + 19 = 35
     * nov = 13 + 14 + 21 = 48
     * dec = 3 + 4 + 2 = 9
     */
    private static int getMonth(String monthString) {
        int hash = Character.toLowerCase(monthString.charAt(0)) +
                Character.toLowerCase(monthString.charAt(1)) +
                Character.toLowerCase(monthString.charAt(2)) - 3 * 'a';
        switch (hash) {
            case 22:
                return Calendar.JANUARY;
            case 10:
                return Calendar.FEBRUARY;
            case 29:
                return Calendar.MARCH;
            case 32:
                return Calendar.APRIL;
            case 36:
                return Calendar.MAY;
            case 42:
                return Calendar.JUNE;
            case 40:
                return Calendar.JULY;
            case 26:
                return Calendar.AUGUST;
            case 37:
                return Calendar.SEPTEMBER;
            case 35:
                return Calendar.OCTOBER;
            case 48:
                return Calendar.NOVEMBER;
            case 9:
                return Calendar.DECEMBER;
            default:
                throw new IllegalArgumentException();
        }
    }

    private static int getYear(String yearString) {
        if (yearString.length() == 2) {
            int year = (yearString.charAt(0) - '0') * 10
                    + (yearString.charAt(1) - '0');
            if (year >= 70) {
                return year + 1900;
            } else {
                return year + 2000;
            }
        } else if (yearString.length() == 3) {
            // According to RFC 2822, three digit years should be added to 1900.
            int year = (yearString.charAt(0) - '0') * 100
                    + (yearString.charAt(1) - '0') * 10
                    + (yearString.charAt(2) - '0');
            return year + 1900;
        } else if (yearString.length() == 4) {
             return (yearString.charAt(0) - '0') * 1000
                    + (yearString.charAt(1) - '0') * 100
                    + (yearString.charAt(2) - '0') * 10
                    + (yearString.charAt(3) - '0');
        } else {
             return 1970;
        }
    }

    private static TimeOfDay getTime(String timeString) {
        // HH might be H
        int i = 0;
        int hour = timeString.charAt(i++) - '0';
        if (timeString.charAt(i) != ':')
            hour = hour * 10 + (timeString.charAt(i++) - '0');
        // Skip ':'
        i++;
        
        int minute = (timeString.charAt(i++) - '0') * 10
                    + (timeString.charAt(i++) - '0');
        // Skip ':'
        i++;
        
        int second = (timeString.charAt(i++) - '0') * 10
                  + (timeString.charAt(i++) - '0');

        return new TimeOfDay(hour, minute, second);        
    }
}