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API for Google App Engine standard environment with some of the dependencies shaded (repackaged)
/*
* Copyright 2021 Google LLC
*
* 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
*
* https://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.google.appengine.api.search;
import com.google.apphosting.api.AppEngineInternal;
import java.text.DateFormat;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;
/**
* A utility class that centralizes processing of dates.
*
*/
@AppEngineInternal
public final class DateUtil {
/**
* The milliseconds in a day.
*/
public static final int MILLISECONDS_IN_DAY = 24 * 60 * 60 * 1000;
/**
* The UTC time zone.
*/
private static final ThreadLocal UTC_TZ =
new ThreadLocal() {
@Override protected TimeZone initialValue() {
return TimeZone.getTimeZone("UTC");
}
};
private static DateFormat getDateFormat(String formatString) {
DateFormat format = new SimpleDateFormat(formatString, Locale.US);
format.setTimeZone(UTC_TZ.get());
return format;
}
private static final ThreadLocal ISO8601_SIMPLE =
new ThreadLocal() {
@Override protected DateFormat initialValue() {
return getDateFormat("yyyy-MM-dd");
}
};
private static final ThreadLocal ISO8601_DATE_TIME_SIMPLE =
new ThreadLocal() {
@Override protected DateFormat initialValue() {
return getDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
}
};
private static final ThreadLocal ISO8601_DATE_TIME_SIMPLE_ERA =
new ThreadLocal() {
@Override protected DateFormat initialValue() {
return getDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'G");
}
};
private DateUtil() {
}
/**
* Get a UTC calendar with Locale US.
*/
private static Calendar getCalendarUTC() {
return new GregorianCalendar(UTC_TZ.get(), Locale.US);
}
/**
* Formats a date according ISO 8601 full date time format. Currently,
* this is used to print dates for error messages.
*
* @param date the date to format as a string
* @return a string representing the date in ISO 8601 format
*/
public static String formatDateTime(Date date) {
if (date == null) {
return null;
}
return isBeforeCommonEra(date) ?
ISO8601_DATE_TIME_SIMPLE_ERA.get().format(date) :
ISO8601_DATE_TIME_SIMPLE.get().format(date);
}
/**
* Returns true if the date is before the common era.
*/
private static boolean isBeforeCommonEra(Date date) {
Calendar cal = getCalendarUTC();
cal.setTime(date);
return cal.get(Calendar.ERA) == GregorianCalendar.BC;
}
/**
* Parses an ISO 8601 into a {@link Date} object.
*
* This function is only used for deserializing legacy "yyyy-MM-dd"
* formatted dates stored in backend. These are currently not supporting
* BC Era dates, so neither will this function.
*
* @param dateString the ISO 8601 formatted string for a date
* @return the {@link Date} parsed from the date string
*/
private static Date parseDate(String dateString) {
// We don't need to support parsing BCE dates since none have or
// are being written to backend.
ParsePosition pos = new ParsePosition(0);
Date d = ISO8601_SIMPLE.get().parse(dateString, pos);
if (pos.getIndex() < dateString.length()) {
throw new IllegalArgumentException(
String.format("Failed to parse date string \"%s\"", dateString));
}
return d;
}
/**
* Converts date into a string containing the milliseconds since the UNIX Epoch.
*
* @param date the date to serialize as a string
* @return a string representing the date as milliseconds since the UNIX Epoch
*/
public static String serializeDate(Date date) {
return date == null ? "" : Long.toString(date.getTime());
}
/**
* Converts a string containing the milliseconds since the UNIX Epoch into a Date.
*
* Two formats of date string are supported: "yyyy-MM-dd" and a long. Eventually,
* the "yyyy-MM-dd" format support will be removed.
*
* @param date the date string to deserialize into a date
* @return a date
*/
public static Date deserializeDate(String date) {
if (date == null) {
return null;
}
// TODO: remove this code to capture "yyyy-MM-dd" formatted dates when the API
// and backend are both using long representation, and a map-reduce has been used
// to replace the date formatted strings in backend.
if (date.startsWith("-")) {
if (date.length() > 1 && date.indexOf('-', 1) >= 0) {
// This should not happen, since we have never written negative years correctly.
return parseDate(date);
}
} else {
if (date.indexOf('-') > 0) {
return parseDate(date);
}
}
return new Date(Long.parseLong(date));
}
/**
* Constructs a {@link Date} set to the UNIX Epoch plus days plus milliseconds.
*
* @param days the number of days to add to the UNIX Epoch to
* get a Date
* @param milliseconds the number of milliseconds to add to the date
* @return the Date with number of days plus Epoch
*/
public static final Date getEpochPlusDays(int days, int milliseconds) {
Calendar cal = getCalendarUTC();
cal.setTimeInMillis(0L);
cal.add(Calendar.DATE, days);
cal.add(Calendar.MILLISECOND, milliseconds);
return cal.getTime();
}
}