Java tutorial
/* * Copyright 2007 Google Inc. * * 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 java.util; import com.google.gwt.core.client.JsDate; import java.io.Serializable; /** * Represents a date and time. */ public class Date implements Cloneable, Comparable<Date>, Serializable { /** * Encapsulates static data to avoid Date itself having a static initializer. */ private static class StringData { public static final String[] DAYS = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" }; public static final String[] MONTHS = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; } public static long parse(String s) { double parsed = JsDate.parse(s); if (Double.isNaN(parsed)) { throw new IllegalArgumentException(); } return (long) parsed; } // CHECKSTYLE_OFF: Matching the spec. public static long UTC(int year, int month, int date, int hrs, int min, int sec) { return (long) JsDate.UTC(year + 1900, month, date, hrs, min, sec, 0); } // CHECKSTYLE_ON /** * Ensure a number is displayed with two digits. * * @return a two-character base 10 representation of the number */ protected static String padTwo(int number) { if (number < 10) { return "0" + number; } else { return String.valueOf(number); } } /** * Package private factory for JSNI use, to allow cheap creation of dates from * doubles. */ static Date createFrom(double milliseconds) { return new Date(milliseconds, false); } /** * JavaScript Date instance. */ private final JsDate jsdate; public Date() { jsdate = JsDate.create(); } public Date(int year, int month, int date) { this(year, month, date, 0, 0, 0); } public Date(int year, int month, int date, int hrs, int min) { this(year, month, date, hrs, min, 0); } public Date(int year, int month, int date, int hrs, int min, int sec) { jsdate = JsDate.create(); jsdate.setFullYear(year + 1900, month, date); jsdate.setHours(hrs, min, sec, 0); fixDaylightSavings(hrs); } public Date(long date) { jsdate = JsDate.create(date); } public Date(String date) { this(Date.parse(date)); } /** * For use by {@link #createFrom(double)}, should inline away. */ Date(double milliseconds, boolean dummyArgForOverloadResolution) { jsdate = JsDate.create(milliseconds); } public boolean after(Date when) { return getTime() > when.getTime(); } public boolean before(Date when) { return getTime() < when.getTime(); } public Object clone() { return new Date(getTime()); } public int compareTo(Date other) { return Long.signum(getTime() - other.getTime()); } @Override public boolean equals(Object obj) { return ((obj instanceof Date) && (getTime() == ((Date) obj).getTime())); } public int getDate() { return jsdate.getDate(); } public int getDay() { return jsdate.getDay(); } public int getHours() { return jsdate.getHours(); } public int getMinutes() { return jsdate.getMinutes(); } public int getMonth() { return jsdate.getMonth(); } public int getSeconds() { return jsdate.getSeconds(); } public long getTime() { return (long) jsdate.getTime(); } public int getTimezoneOffset() { return jsdate.getTimezoneOffset(); } public int getYear() { return jsdate.getFullYear() - 1900; } @Override public int hashCode() { long time = getTime(); return (int) (time ^ (time >>> 32)); } public void setDate(int date) { int hours = jsdate.getHours(); jsdate.setDate(date); fixDaylightSavings(hours); } public void setHours(int hours) { jsdate.setHours(hours); fixDaylightSavings(hours); } public void setMinutes(int minutes) { int hours = getHours() + minutes / 60; jsdate.setMinutes(minutes); fixDaylightSavings(hours); } public void setMonth(int month) { int hours = jsdate.getHours(); jsdate.setMonth(month); fixDaylightSavings(hours); } public void setSeconds(int seconds) { int hours = getHours() + seconds / (60 * 60); jsdate.setSeconds(seconds); fixDaylightSavings(hours); } public void setTime(long time) { jsdate.setTime(time); } public void setYear(int year) { int hours = jsdate.getHours(); jsdate.setFullYear(year + 1900); fixDaylightSavings(hours); } public String toGMTString() { return jsdate.getUTCDate() + " " + StringData.MONTHS[jsdate.getUTCMonth()] + " " + jsdate.getUTCFullYear() + " " + padTwo(jsdate.getUTCHours()) + ":" + padTwo(jsdate.getUTCMinutes()) + ":" + padTwo(jsdate.getUTCSeconds()) + " GMT"; } public String toLocaleString() { return jsdate.toLocaleString(); } @Override public String toString() { // Compute timezone offset. The value that getTimezoneOffset returns is // backwards for the transformation that we want. int offset = -jsdate.getTimezoneOffset(); String hourOffset = ((offset >= 0) ? "+" : "") + (offset / 60); String minuteOffset = padTwo(Math.abs(offset) % 60); return StringData.DAYS[jsdate.getDay()] + " " + StringData.MONTHS[jsdate.getMonth()] + " " + padTwo(jsdate.getDate()) + " " + padTwo(jsdate.getHours()) + ":" + padTwo(jsdate.getMinutes()) + ":" + padTwo(jsdate.getSeconds()) + " GMT" + hourOffset + minuteOffset + " " + jsdate.getFullYear(); } /* * Some browsers have the following behavior: * * // Assume a U.S. time zone with daylight savings * // Set a non-existent time: 2:00 am Sunday March 8, 2009 * var date = new Date(2009, 2, 8, 2, 0, 0); * var hours = date.getHours(); // returns 1 * * The equivalent Java code will return 3. To compensate, we determine the * amount of daylight savings adjustment by comparing the time zone offsets * for the requested time and a time one day later, and add the adjustment to * the hours and minutes of the requested time. */ /** * Detects if the requested time falls into a non-existent time range due to * local time advancing into daylight savings time. If so, push the requested * time forward out of the non-existent range. */ private void fixDaylightSavings(int hours) { if ((jsdate.getHours() % 24) != (hours % 24)) { JsDate copy = JsDate.create(jsdate.getTime()); copy.setDate(copy.getDate() + 1); int timeDiff = jsdate.getTimezoneOffset() - copy.getTimezoneOffset(); // If the time zone offset is changing, advance the hours and // minutes from the initially requested time by the change amount if (timeDiff > 0) { int timeDiffHours = timeDiff / 60; int timeDiffMinutes = timeDiff % 60; int day = jsdate.getDate(); int badHours = jsdate.getHours(); if (badHours + timeDiffHours >= 24) { day++; } JsDate newTime = JsDate.create(jsdate.getFullYear(), jsdate.getMonth(), day, hours + timeDiffHours, jsdate.getMinutes() + timeDiffMinutes, jsdate.getSeconds(), jsdate.getMilliseconds()); jsdate.setTime(newTime.getTime()); } } } }