timezone.java

j2me下的1套UI框架.包含j2me开发中会应用的各种低级组件

package com.jmobilecore.support;

/**
 * The <code>TimeZone</code> represents a time zone offset and daylight savings.
 *
 * @author Greg Gridin
 */
public class TimeZone {

    /**
     * The list of available timezones
     */
    static final protected String[] ids = {"WST", "MSK", "EET", "CET", "GMT", "AST", "EST", "CST", "MST", "PST", "AKST", "HST"};

    /**
     * Timezone's offsets
     */
    static final protected int[] offsets = {8 * 60 * 60 * 1000, 3 * 60 * 60 * 1000,
                                            2 * 60 * 60 * 1000, 1 * 60 * 60 * 1000,
                                            0, -4 * 60 * 60 * 1000,
                                            -5 * 60 * 60 * 1000, -6 * 60 * 60 * 1000,
                                            -7 * 60 * 60 * 1000, -8 * 60 * 60 * 1000,
                                            -9 * 60 * 60 * 1000, -10 * 60 * 60 * 1000};

    /**
     * The default timezone (GMT)
     *
     * @see #getDefault()
     */
    static final protected TimeZone defTimeZone = new TimeZone("GMT", 0);

    /**
     * Gets all the available IDs supported.
     *
     * @return an array of <code>String</code> IDs.
     */
    static public String[] getAvailableIDs() {
        return ids;
    }

    /**
     * Gets all the available offsets supported.
     *
     * @return an array of offsets.
     * @see #getAvailableIDs()
     */
    static public int[] getAvailableOffsets() {
        return offsets;
    }

    /**
     * Gets the default TimeZone.
     *
     * @see #defTimeZone
     */
    static public TimeZone getDefault() {
        return defTimeZone;
    }

    /**
     * Gets the TimeZone for the given ID.
     *
     * @param timezone the ID for a TimeZone
     * @return the specified TimeZone, or the GMT zone if the given timezone id cannot be understood
     * @see #ids
     */
    static public TimeZone getTimeZone(String timezone) {
        int len = ids.length;
        for (int i = 0; i < len; i++) {
            if (ids[i].equals(timezone)) {
                return new TimeZone(ids[i], offsets[i]);
            }
        }
        return defTimeZone;
    }

    /**
     * The current TimeZone id
     */
    protected String id = "GMT";

    /**
     * The current TimeZone offset
     */
    protected int offset = 0;

    /**
     * The current TimeZone daylight setting
     */
    public boolean daylight = false;

    /**
     * Constructor for the TimeZone class
     *
     * @param id     the TimeZone id
     * @param offset the TimeZone offset
     */
    protected TimeZone(String id, int offset) {
        this.id = id;
        this.offset = offset;
    }

    /**
     * Gets the ID of this time zone.
     *
     * @return the ID of this time zone.
     */
    public String getID() {
        return id;
    }

    /**
     * Gets the time zone offset, for current date, modified in case of daylight savings.
     * This is the offset to add to UTC to get local time.
     *
     * @param era       the era of the given date.
     * @param year      the year in the given date.
     * @param month     the month in the given date. Month is 0-based. e.g., 0 for January.
     * @param day       the day-in-month of the given date.
     * @param dayOfWeek the day-of-week of the given date.
     * @param millis    the milliseconds in day in standard local time.
     * @return the offset in milliseconds to add to GMT to get local time.
     */
    public int getOffset(int era, int year, int month, int day, int dayOfWeek, int millis) {
        return getRawOffset() + (daylight ? 60 * 60 * 1000 : 0);
    }

    /**
     * Gets if this time zone uses daylight savings time.
     *
     * @return true if this time zone uses daylight savings time, false, otherwise.
     */
    public boolean useDaylightTime() {
        return true;
    }

    /**
     * Returns the amount of time in milliseconds to add to UTC to get standard time in this time zone.
     * Because this value is not affected by daylight saving time, it is called raw offset.
     *
     * @return the amount of raw offset time in milliseconds to add to UTC.
     */
    public int getRawOffset() {
        return offset;
    }

} // class TimeZone