dateformat.java

来自「《移动Agent技术》一书的所有章节源代码。」· Java 代码 · 共 622 行 · 第 1/2 页

    /**
     * Parse a date/time string according to the given parse position.  For
     * example, a time text "07/10/96 4:5 PM, PDT" will be parsed into a Date
     * that is equivalent to Date(837039928046).
     *
     * <p> By default, parsing is lenient: If the input is not in the form used
     * by this object's format method but can still be parsed as a date, then
     * the parse succeeds.  Clients may insist on strict adherence to the
     * format by calling setLenient(false).
     *
     * @see java.text.DateFormat#setLenient(boolean)
     *
     * @param text  The date/time string to be parsed
     *
     * @param pos   On input, the position at which to start parsing; on
     *              output, the position at which parsing terminated, or the
     *              start position if the parse failed.
     *
     * @return      A Date, or null if the input could not be parsed
     */
    public abstract Date parse(String text, ParsePosition pos);

    /**
     * Parse a date/time string into an Object.  This convenience method simply
     * calls parse(String, ParsePosition).
     *
     * @see #parse(String, ParsePosition)
     */
    public Object parseObject (String source, ParsePosition pos)
    {
        return parse(source, pos);
    }

    /**
     * Constant for full style pattern.
     */
    public static final int FULL = 0;
    /**
     * Constant for long style pattern.
     */
    public static final int LONG = 1;
    /**
     * Constant for medium style pattern.
     */
    public static final int MEDIUM = 2;
    /**
     * Constant for short style pattern.
     */
    public static final int SHORT = 3;
    /**
     * Constant for default style pattern.
     */
    public static final int DEFAULT = MEDIUM;

    /**
     * Gets the time formatter with the default formatting style
     * for the default locale.
     * @return a time formatter.
     */
    public final static DateFormat getTimeInstance()
    {
        return get(DEFAULT, -1, Locale.getDefault());
    }

    /**
     * Gets the time formatter with the given formatting style
     * for the default locale.
     * @param style the given formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @return a time formatter.
     */
    public final static DateFormat getTimeInstance(int style)
    {
        return get(style, -1, Locale.getDefault());
    }

    /**
     * Gets the time formatter with the given formatting style
     * for the given locale.
     * @param style the given formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @param inLocale the given locale.
     * @return a time formatter.
     */
    public final static DateFormat getTimeInstance(int style,
                                                 Locale aLocale)
    {
        return get(style, -1, aLocale);
    }

    /**
     * Gets the date formatter with the default formatting style
     * for the default locale.
     * @return a date formatter.
     */
    public final static DateFormat getDateInstance()
    {
        // +4 to set the correct index for getting data out of
        // LocaleElements.
        return get(-1, DEFAULT + 4, Locale.getDefault());
    }

    /**
     * Gets the date formatter with the given formatting style
     * for the default locale.
     * @param style the given formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @return a date formatter.
     */
    public final static DateFormat getDateInstance(int style)
    {
        return get(-1, style + 4, Locale.getDefault());
    }

    /**
     * Gets the date formatter with the given formatting style
     * for the given locale.
     * @param style the given formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @param inLocale the given locale.
     * @return a date formatter.
     */
    public final static DateFormat getDateInstance(int style,
                                                 Locale aLocale)
    {
        return get(-1, style + 4, aLocale);
    }

    /**
     * Gets the date/time formatter with the default formatting style
     * for the default locale.
     * @return a date/time formatter.
     */
    public final static DateFormat getDateTimeInstance()
    {
        return get(DEFAULT, DEFAULT + 4, Locale.getDefault());
    }

    /**
     * Gets the date/time formatter with the given date and time
     * formatting styles for the default locale.
     * @param dateStyle the given date formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @param timeStyle the given time formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @return a date/time formatter.
     */
    public final static DateFormat getDateTimeInstance(int dateStyle,
                                                       int timeStyle)
    {
        return get(timeStyle, dateStyle + 4, Locale.getDefault());
    }

    /**
     * Gets the date/time formatter with the given formatting styles
     * for the given locale.
     * @param dateStyle the given date formatting style.
     * @param timeStyle the given time formatting style.
     * @param inLocale the given locale.
     * @return a date/time formatter.
     */
    public final static DateFormat
        getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
    {
        return get(timeStyle, dateStyle + 4, aLocale);
    }

    /**
     * Get a default date/time formatter that uses the SHORT style for both the
     * date and the time.
     */
    public final static DateFormat getInstance() {
        return getDateTimeInstance(SHORT, SHORT);
    }

    /**
     * Gets the set of locales for which DateFormats are installed.
     * @return the set of locales for which DateFormats are installed.
     */
    public static Locale[] getAvailableLocales()
    {
        return LocaleData.getAvailableLocales("DateTimePatterns");
    }

    /**
     * Set the calendar to be used by this date format.  Initially, the default
     * calendar for the specified or default locale is used.
     */
    public void setCalendar(Calendar newCalendar)
    {
        this.calendar = newCalendar;
    }

    /**
     * Gets the calendar associated with this date/time formatter.
     * @return the calendar associated with this date/time formatter.
     */
    public Calendar getCalendar()
    {
        return calendar;
    }

    /**
     * Allows you to set the number formatter.
     * @param newNumberFormat the given new NumberFormat.
     */
    public void setNumberFormat(NumberFormat newNumberFormat)
    {
        this.numberFormat = newNumberFormat;
    }

    /**
     * Gets the number formatter which this date/time formatter uses to
     * format and parse a time.
     * @return the number formatter which this date/time formatter uses.
     */
    public NumberFormat getNumberFormat()
    {
        return numberFormat;
    }

    /**
     * Sets the time zone for the calendar of this DateFormat object.
     * @param zone the given new time zone.
     */
    public void setTimeZone(TimeZone zone)
    {
        calendar.setTimeZone(zone);
    }

    /**
     * Gets the time zone.
     * @return the time zone associated with the calendar of DateFormat.
     */
    public TimeZone getTimeZone()
    {
        return calendar.getTimeZone();
    }

    /**
     * Specify whether or not date/time parsing is to be lenient.  With
     * lenient parsing, the parser may use heuristics to interpret inputs that
     * do not precisely match this object's format.  With strict parsing,
     * inputs must match this object's format.
     * @see java.util.Calendar#setLenient
     */
    public void setLenient(boolean lenient)
    {
        calendar.setLenient(lenient);
    }

    /**
     * Tell whether date/time parsing is to be lenient.
     */
    public boolean isLenient()
    {
        return calendar.isLenient();
    }

    /**
     * Overrides hashCode
     */
    public int hashCode() {
        return numberFormat.hashCode();
        // just enough fields for a reasonable distribution
    }

    /**
     * Overrides equals
     */
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null || getClass() != obj.getClass()) return false;
        DateFormat other = (DateFormat) obj;
        return (// calendar.equivalentTo(other.calendar) // THIS API DOESN'T EXIST YET!
                calendar.getFirstDayOfWeek() == other.calendar.getFirstDayOfWeek() &&
                calendar.getMinimalDaysInFirstWeek() == other.calendar.getMinimalDaysInFirstWeek() &&
                calendar.isLenient() == other.calendar.isLenient() &&
                calendar.getTimeZone().equals(other.calendar.getTimeZone()) &&
                numberFormat.equals(other.numberFormat));
    }

    /**
     * Overrides Cloneable
     */
    public Object clone()
    {
        DateFormat other = (DateFormat) super.clone();
        other.calendar = (Calendar) calendar.clone();
        other.numberFormat = (NumberFormat) numberFormat.clone();
        return other;
    }

    private static DateFormat get(int timeStyle, /* -1 for no time */
                                  int dateStyle, /* -1 for no date */
                                  Locale loc) {
        try {
            ResourceBundle resource
                = ResourceBundle.getBundle
                ("java.text.resources.LocaleElements", loc);
            return new SimpleDateFormat(timeStyle, dateStyle, loc);

        } catch (MissingResourceException e) {
            return new SimpleDateFormat("M/d/yy h:mm a");
        }
    }

    protected DateFormat() { }

}