datetool.java

一个用于java web页面开发的开源包

    {
        return getValue(field, getCalendar());
    }

    /**
     * Returns the specified value of the specified date,
     * or null if the field or date is invalid.  The field may be
     * an Integer or it may be the name of the field as a String.
     *
     * @param field the corresponding Integer value or String name of the desired value
     * @param date the date/calendar from which the field value will be taken
     * @since VelocityTools 1.2
     */
    public Integer getValue(Object field, Object date)
    {
        if (field == null)
        {
            return null;
        }

        int fieldValue;
        if (field instanceof Integer)
        {
            fieldValue = ((Integer)field).intValue();
        }
        // all the public static field names are upper case
        String fstr = field.toString().toUpperCase();
        try
        {
            Field clsf = Calendar.class.getField(fstr);
            fieldValue = clsf.getInt(Calendar.getInstance());
        }
        catch (Exception e)
        {
            return null;
        }
        return getValue(fieldValue, date);
    }

    /**
     * Returns the specified value of the specified date,
     * or null if the field or date is invalid.
     *
     * @param field the int for the desired field (e.g. Calendar.MONTH)
     * @param date the date/calendar from which the field value will be taken
     * @since VelocityTools 1.2
     */
    public Integer getValue(int field, Object date)
    {
        Calendar cal = toCalendar(date);
        if (cal == null)
        {
            return null;
        }
        return new Integer(cal.get(field));
    }


    // ------------------------- formatting methods ---------------------------

    /**
     * Returns a formatted string representing the date returned by
     * {@link #getDate()}.  In its default implementation, this method
     * allows you to retrieve the current date in standard formats by
     * simply doing things like <code>$date.medium</code> or
     * <code>$date.full</code>.  If you want only the date or time portion
     * you can specify that along with the standard formats. (e.g.
     * <code>$date.medium_date</code> or <code>$date.short_time</code>)
     * More complex or custom formats can be retrieved
     * by using the full method syntax. (e.g. $date.get('E, MMMM d'))
     *
     * @param format the formatting instructions
     * @return a formatted representation of the date returned by
     *         {@link #getDate()}
     * @see #format(String format, Object obj, Locale locale, TimeZone timezone)
     * @since VelocityTools 1.1
     */
    public String get(String format)
    {
        return format(format, getDate());
    }

    /**
     * Returns a formatted string representing the date and/or time given by
     * {@link #getDate()} in standard, localized patterns.
     *
     * @param dateStyle the style pattern for the date
     * @param timeStyle the style pattern for the time
     * @return a formatted representation of the date returned by
     *         {@link #getDate()}
     * @see DateFormat
     * @see #format(String dateStyle, String timeStyle, Object obj, Locale locale, TimeZone timezone)
     * @since VelocityTools 1.1
     */
    public String get(String dateStyle, String timeStyle)
    {
        return format(dateStyle, timeStyle, getDate(), getLocale());
    }


    /**
     * Converts the specified object to a date and formats it according to
     * the pattern or style returned by {@link #getFormat()}.
     *
     * @param obj the date object to be formatted
     * @return the specified date formatted as a string
     * @see #format(String format, Object obj, Locale locale, TimeZone timezone)
     * @since VelocityTools 1.1
     */
    public String format(Object obj)
    {
        return format(getFormat(), obj);
    }

    /**
     * Converts the specified object to a date and returns
     * a formatted string representing that date in the locale
     * returned by {@link #getLocale()}.
     *
     * @param format the formatting instructions
     * @param obj the date object to be formatted
     * @return a formatted string for this locale representing the specified
     *         date or <code>null</code> if the parameters are invalid
     * @see #format(String format, Object obj, Locale locale, TimeZone timezone)
     */
    public String format(String format, Object obj)
    {
        return format(format, obj, getLocale());
    }

    /**
     * Converts the specified object to a date and returns
     * a formatted string representing that date in the specified
     * {@link Locale}.
     *
     * @param format the formatting instructions
     * @param obj the date object to be formatted
     * @param locale the locale to be used when formatting
     * @return the given date as a formatted string
     * @see #format(String format, Object obj, Locale locale, TimeZone timezone)
     */
    public String format(String format, Object obj, Locale locale)
    {
        return format(format, obj, locale, getTimeZone());
    }

    /**
     * Returns a formatted string representing the specified date,
     * {@link Locale}, and {@link TimeZone}.
     *
     * <p>
     * The specified format may be a standard style pattern ('full', 'long',
     * 'medium', 'short', or 'default').
     * </p>
     * <p>
     * You may also specify that you want only the date or time portion be
     * appending '_date' or '_time' respectively to the standard style pattern.
     * (e.g. 'full_date' or 'long_time')
     * </p>
     * <p>
     * If the format fits neither of these patterns, then the output
     * will be formatted according to the symbols defined by
     * {@link SimpleDateFormat}:
     * <pre>
     *   Symbol   Meaning                 Presentation        Example
     *   ------   -------                 ------------        -------
     *   G        era designator          (Text)              AD
     *   y        year                    (Number)            1996
     *   M        month in year           (Text & Number)     July & 07
     *   d        day in month            (Number)            10
     *   h        hour in am/pm (1~12)    (Number)            12
     *   H        hour in day (0~23)      (Number)            0
     *   m        minute in hour          (Number)            30
     *   s        second in minute        (Number)            55
     *   S        millisecond             (Number)            978
     *   E        day in week             (Text)              Tuesday
     *   D        day in year             (Number)            189
     *   F        day of week in month    (Number)            2 (2nd Wed in July)
     *   w        week in year            (Number)            27
     *   W        week in month           (Number)            2
     *   a        am/pm marker            (Text)              PM
     *   k        hour in day (1~24)      (Number)            24
     *   K        hour in am/pm (0~11)    (Number)            0
     *   z        time zone               (Text)              Pacific Standard Time
     *   '        escape for text         (Delimiter)
     *   ''       single quote            (Literal)           '
     *
     *   Examples: "E, MMMM d" will result in "Tue, July 24"
     *             "EEE, M-d (H:m)" will result in "Tuesday, 7-24 (14:12)"
     * </pre>
     * </p>
     *
     * @param format the custom or standard pattern to be used
     * @param obj the date to format
     * @param locale the {@link Locale} to format the date for
     * @param timezone the {@link TimeZone} to be used when formatting
     * @return a formatted string representing the specified date or
     *         <code>null</code> if the parameters are invalid
     * @since VelocityTools 1.1
     */
    public String format(String format, Object obj,
                         Locale locale, TimeZone timezone)
    {
        Date date = toDate(obj);
        DateFormat df = getDateFormat(format, locale, timezone);
        if (date == null || df == null)
        {
            return null;
        }
        return df.format(date);
    }


    /**
     * Returns the specified date as a string formatted according to the
     * specified date and/or time styles.
     *
     * @param dateStyle the style pattern for the date
     * @param timeStyle the style pattern for the time
     * @param obj the date to be formatted
     * @return a formatted representation of the given date
     * @see #format(String dateStyle, String timeStyle, Object obj, Locale locale, TimeZone timezone)
     * @since VelocityTools 1.1
     */
    public String format(String dateStyle, String timeStyle, Object obj)
    {
        return format(dateStyle, timeStyle, obj, getLocale());
    }

    /**
     * Returns the specified date as a string formatted according to the
     * specified {@link Locale} and date and/or time styles.
     *
     * @param dateStyle the style pattern for the date
     * @param timeStyle the style pattern for the time
     * @param obj the date to be formatted
     * @param locale the {@link Locale} to be used for formatting the date
     * @return a formatted representation of the given date
     * @see #format(String dateStyle, String timeStyle, Object obj, Locale locale, TimeZone timezone)
     * @since VelocityTools 1.1
     */
    public String format(String dateStyle, String timeStyle,
                         Object obj, Locale locale)
    {
        return format(dateStyle, timeStyle, obj, locale, getTimeZone());
    }

    /**
     * Returns the specified date as a string formatted according to the
     * specified {@link Locale} and date and/or time styles.
     *
     * @param dateStyle the style pattern for the date
     * @param timeStyle the style pattern for the time
     * @param obj the date to be formatted
     * @param locale the {@link Locale} to be used for formatting the date
     * @param timezone the {@link TimeZone} the date should be formatted for
     * @return a formatted representation of the given date
     * @see java.text.DateFormat
     * @see #format(String dateStyle, String timeStyle, Object obj, Locale locale, TimeZone timezone)
     * @since VelocityTools 1.1
     */
    public String format(String dateStyle, String timeStyle,
                         Object obj, Locale locale, TimeZone timezone)
    {
        Date date = toDate(obj);
        DateFormat df = getDateFormat(dateStyle, timeStyle, locale, timezone);
        if (date == null || df == null)
        {
            return null;
        }
        return df.format(date);
    }


    // -------------------------- DateFormat creation methods --------------

    /**
     * Returns a {@link DateFormat} instance for the specified
     * format, {@link Locale}, and {@link TimeZone}.  If the format
     * specified is a standard style pattern, then a date-time instance
     * will be returned with both the date and time styles set to the
     * specified style.  If it is a custom format, then a customized
     * {@link SimpleDateFormat} will be returned.
     *
     * @param format the custom or standard formatting pattern to be used
     * @param locale the {@link Locale} to be used
     * @param timezone the {@link TimeZone} to be used
     * @return an instance of {@link DateFormat}
     * @see SimpleDateFormat
     * @see DateFormat
     * @since VelocityTools 1.1
     */
    public DateFormat getDateFormat(String format, Locale locale,
                                    TimeZone timezone)
    {
        if (format == null)
        {
            return null;
        }

        DateFormat df = null;
        // do they want a date instance
        if (format.endsWith("_date"))
        {
            String fmt = format.substring(0, format.length() - 5);
            int style = getStyleAsInt(fmt);
            df = getDateFormat(style, -1, locale, timezone);