calendar.java

已经移植好的java虚拟机

/*
 * @(#)Calendar.java    1.42 98/09/23
 *
 * (C) Copyright Taligent, Inc. 1996-1998 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996-1998 - All Rights Reserved
 *
 * Portions copyright (c) 1996-2002 Sun Microsystems, Inc. All Rights Reserved.
 *
 *   The original version of this source code and documentation is copyrighted
 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
 * materials are provided under terms of a License Agreement between Taligent
 * and Sun. This technology is protected by multiple US and International
 * patents. This notice and attribution to Taligent may not be removed.
 *   Taligent is a registered trademark of Taligent, Inc.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and without
 * fee is hereby granted provided that this copyright notice
 * appears in all copies. Please refer to the file "copyright.html"
 * for further important copyright and licensing information.
 *
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * Use is subject to license terms.
 */

package java.util;

/**
 * <code>Calendar</code> is an abstract class for getting and setting dates
 * using a set of integer fields such as
 * <code>YEAR</code>, <code>MONTH</code>, <code>DAY</code>,
 * and so on. (A <code>Date</code> object represents a specific instant in
 * time with millisecond precision. See
 * {@link Date}
 * for information about the <code>Date</code> class.)
 *
 * <p>
 * Subclasses of <code>Calendar</code> interpret a <code>Date</code>
 * according to the rules of a specific calendar system.
 *
 * <p>
 * Like other locale-sensitive classes, <code>Calendar</code> provides a
 * class method, <code>getInstance</code>, for getting a generally useful
 * object of this type.
 * <blockquote>
 * <pre>
 * Calendar rightNow = Calendar.getInstance();
 * </pre>
 * </blockquote>
 *
 * <p>
 * A <code>Calendar</code> object can produce all the time field values
 * needed to implement the date-time formatting for a particular language
 * and calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
 *
 * <p>
 * When computing a <code>Date</code> from time fields,
 * there may be insufficient information to compute the
 * <code>Date</code> (such as only year and month but no day in the month).
 *
 * <p>
 * <strong>Insufficient information.</strong> The calendar will use default
 * information to specify the missing fields. This may vary by calendar; for
 * the Gregorian calendar, the default for a field is the same as that of the
 * start of the epoch: i.e., YEAR = 1970, MONTH = JANUARY, DATE = 1, etc.
 *
 * <p>
 * <strong>Inconsistent information.</strong> In the J2SE calendar, it is
 * possible to set fields inconsistently. However, in this subset, the
 * DAY_OF_WEEK field cannot be set, and only a subset of the other J2SE
 * Calendar fields are included. So it is not possible to set
 * inconsistent data.
 * <p>
 *
 * <strong>Note:</strong> The ambiguity in interpretation of what day midnight
 * belongs to, is resolved as so: midnight "belongs" to the following day.<br>
 * 23:59 on Dec 31, 1969 &lt; 00:00 on Jan 1, 1970.<br>
 * 12:00 PM is midday, and 12:00 AM is midnight.<br>
 * 11:59 PM on Jan 1 &lt; 12:00 AM on Jan 2 &lt; 12:01 AM on Jan 2.<br>
 * 11:59 AM on Mar 10 &lt; 12:00 PM on Mar 10 &lt; 12:01 PM on Mar 10.<br>
 * 24:00 or greater are invalid.
 * Hours greater than 12 are invalid in AM/PM mode.
 * Setting the time will never change the date.
 * <p>
 * If equivalent times are entered in AM/PM or 24 hour mode, equality will be
 * determined by the actual time rather than the entered time.
 * <p>
 *
 * This class is a subset for J2ME of the J2SE Calendar class.
 * Many methods and variables have been
 * pruned, and other methods simplified, in an effort to reduce the size
 * of this class.
 *
 *
 * @see          TimeZone
 * @version      1.0 (J2ME MIDP)
 * @author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu, Brian Modra
 */
public abstract class Calendar {
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * year. This is a calendar-specific value.
   */
  public final static int YEAR = 1;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * month. This is a calendar-specific value.
   */
  public final static int MONTH = 2;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * day of the month. This is a synonym for <code>DAY_OF_MONTH</code>.
   * @see #DAY_OF_MONTH
   */
  public final static int DATE = 5;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * day of the month. This is a synonym for <code>DATE</code>.
   * @see #DATE
   */
  public final static int DAY_OF_MONTH = 5;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * day of the week.
   */
  public final static int DAY_OF_WEEK = 7;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating
   * whether the <code>HOUR</code> is before or after noon.
   * E.g., at 10:04:15.250 PM the <code>AM_PM</code> is <code>PM</code>.
   * @see #AM
   * @see #PM
   * @see #HOUR
   */
  public final static int AM_PM = 9;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * hour of the morning or afternoon. <code>HOUR</code> is used for the
   * 12-hour clock.
   * E.g., at 10:04:15.250 PM the <code>HOUR</code> is 10.
   * @see #AM_PM
   * @see #HOUR_OF_DAY
   */
  public final static int HOUR = 10;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * hour of the day. <code>HOUR_OF_DAY</code> is used for the 24-hour clock.
   * E.g., at 10:04:15.250 PM the <code>HOUR_OF_DAY</code> is 22.
   */
  public final static int HOUR_OF_DAY = 11;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * minute within the hour.
   * E.g., at 10:04:15.250 PM the <code>MINUTE</code> is 4.
   */
  public final static int MINUTE = 12;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * second within the minute.
   * E.g., at 10:04:15.250 PM the <code>SECOND</code> is 15.
   */
  public final static int SECOND = 13;
  /**
   * Field number for <code>get</code> and <code>set</code> indicating the
   * millisecond within the second.
   * E.g., at 10:04:15.250 PM the <code>MILLISECOND</code> is 250.
   */
  public final static int MILLISECOND = 14;

  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Sunday.
   */
  public final static int SUNDAY = 1;
  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Monday.
   */
  public final static int MONDAY = 2;
  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Tuesday.
   */
  public final static int TUESDAY = 3;
  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Wednesday.
   */
  public final static int WEDNESDAY = 4;
  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Thursday.
   */
  public final static int THURSDAY = 5;
  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Friday.
   */
  public final static int FRIDAY = 6;
  /**
   * Value of the <code>DAY_OF_WEEK</code> field indicating
   * Saturday.
   */
  public final static int SATURDAY = 7;

  /**
   * Value of the <code>MONTH</code> field indicating the
   * first month of the year.
   */
  public final static int JANUARY = 0;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * second month of the year.
   */
  public final static int FEBRUARY = 1;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * third month of the year.
   */
  public final static int MARCH = 2;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * fourth month of the year.
   */
  public final static int APRIL = 3;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * fifth month of the year.
   */
  public final static int MAY = 4;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * sixth month of the year.
   */
  public final static int JUNE = 5;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * seventh month of the year.
   */
  public final static int JULY = 6;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * eighth month of the year.
   */
  public final static int AUGUST = 7;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * ninth month of the year.
   */
  public final static int SEPTEMBER = 8;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * tenth month of the year.
   */
  public final static int OCTOBER = 9;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * eleventh month of the year.
   */
  public final static int NOVEMBER = 10;
  /**
   * Value of the <code>MONTH</code> field indicating the
   * twelfth month of the year.
   */
  public final static int DECEMBER = 11;
  /**
   * Value of the <code>AM_PM</code> field indicating the
   * period of the day from midnight to just before noon.
   */
  public final static int AM = 0;
  /**
   * Value of the <code>AM_PM</code> field indicating the
   * period of the day from noon to just before midnight.
   */
  public final static int PM = 1;

  // Internal notes:
  // Calendar contains two kinds of time representations: current "time" in
  // milliseconds, and a set of time "fields" representing the current time.
  // The two representations are usually in sync, but can get out of sync
  // as follows.
  // 1. Initially, no fields are set, and the time is invalid.
  // 2. If the time is set, all fields are computed and in sync.
  // 3. If a single field is set, the time is invalid.
  // Recomputation of the time and fields happens when the object needs
  // to return a result to the user, or use a result for a computation.

  private int packed_time = 0;
  private int packed_date = 0;
  private int day_field = 0;
  private int dstOffset = 0;
  private boolean dstSet = false;

  /**
   * The currently set time for this calendar, expressed in milliseconds after
   * January 1, 1970, 0:00:00 GMT.
   */
  private long          time;

  /**
   * True if then the value of <code>time</code> is valid.
   * The time is made invalid by a change to an item of <code>field[]</code>.
   * @see #time
   */
  private boolean       millisSet; // NOTE: Make transient when possible

  /**
   * The <code>TimeZone</code> used by this calendar. </code>Calendar</code>
   * uses the time zone data to translate between locale and GMT time.
   */
  private TimeZone        zone;

  //////////////////
  // Class Variables
  //////////////////

  private static final int JAN_1_1_JULIAN_DAY = 1721426; // January 1, year 1 (Gregorian)
  private static final int EPOCH_JULIAN_DAY   = 2440588; // Jaunary 1, 1970 (Gregorian)
  private static final int EPOCH_YEAR = 1970;

  private static final int NUM_DAYS[]
    = {0,31,59,90,120,151,181,212,243,273,304,334}; // 0-based, for day-in-year
  private static final int LEAP_NUM_DAYS[]
    = {0,31,60,91,121,152,182,213,244,274,305,335}; // 0-based, for day-in-year

  // Useful millisecond constants.  Although ONE_DAY and ONE_WEEK can fit
  // into ints, they must be longs in order to prevent arithmetic overflow
  // when performing (bug 4173516).
  private static final int  ONE_SECOND = 1000;
  private static final int  ONE_MINUTE = 60*ONE_SECOND;
  private static final int  ONE_HOUR   = 60*ONE_MINUTE;
  private static final long ONE_DAY    = 24*ONE_HOUR;
  private static final long ONE_WEEK   = 7*ONE_DAY;

  /////////////////////
  // Instance Variables
  /////////////////////

  /**
   * The point at which the Gregorian calendar rules are used, measured in
   * milliseconds from the standard epoch.  Default is October 15, 1582
   * (Gregorian) 00:00:00 UTC or -12219292800000L.  For this value, October 4,
   * 1582 (Julian) is followed by October 15, 1582 (Gregorian).  This
   * corresponds to Julian day number 2299161.
   */
  private static final long gregorianCutover = -12219292800000L;

  /**
   * The year of the gregorianCutover, with 0 representing
   * 1 BC, -1 representing 2 BC, etc.
   */
  private static final int gregorianCutoverYear = 1582;

  private Date date = null;

  /** if both of these are set, the set() method will recalculate
   * the HOUR_OF_DAY using 12hr time.
   */
  private int hour_12hr = -1;
  private int am_pm_12hr = -1;

  /**
   * The platform name
   */
  private static String platform = null;

  /**
   * The root of the classes
   */
  private static String classRoot = null;

  /**
   * Constructs a Calendar with the default time zone
   * and default locale.
   *
   * @see     TimeZone#getDefault
   */
  protected Calendar() {