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Guise™ Internet application framework.
/*
* Copyright © 2005-2008 GlobalMentor, Inc. The value type this converter supports.
* @author Garret Wilson
*/
public abstract class AbstractDateStringLiteralConverter extends AbstractConverter {
/** The array of date format styles (or -1 indicating no corresponding format style) indexed by enumerated styles for quick conversion. */
private static final int[] DATE_FORMAT_STYLES = new int[DateStringLiteralStyle.values().length];
/** The array of time format styles (or -1 indicating no corresponding format style) indexed by enumerated styles for quick conversion. */
private static final int[] TIME_FORMAT_STYLES = new int[TimeStringLiteralStyle.values().length];
/** The date representation style, or null if the date should not be represented. */
private final DateStringLiteralStyle dateStyle;
/** @return The date representation style, or null if the date should not be represented. */
public DateStringLiteralStyle getDateStyle() {
return dateStyle;
}
/** The time representation style, or null if the time should not be represented. */
private final TimeStringLiteralStyle timeStyle;
/** @return The time representation style, or null if the time should not be represented. */
public TimeStringLiteralStyle getTimeStyle() {
return timeStyle;
}
/** The lazily-created cached object for converting dates to and from strings. */
private DateFormat dateFormat = null;
/** The lazily-assigned locale for which a date format was generated. */
private Locale locale = null;
/** The lazily-assigned time zone for which a date format was generated. */
private Locale timeZone = null;
/**
* Determines a date format object appropriate for the session's current locale and time zone.
* @return A date format object appropriate for the session's current locale.
* @see GuiseSession#getLocale()
* @see GuiseSession#getTimeZone()
*/
protected synchronized DateFormat getDateFormat() {
final GuiseSession session = getSession(); //get the Guise session
final Locale sessionLocale = session.getLocale(); //get the current session locale
final TimeZone sessionTimeZone = session.getTimeZone(); //get the current session time zone
if(dateFormat == null || !sessionLocale.equals(locale) || !sessionTimeZone.equals(timeZone)) { //if we haven't yet generated a date format, locale, and/or time zone has changed
dateFormat = createDateFormat(getDateStyle(), getTimeStyle(), sessionLocale, sessionTimeZone); //create a new date format
locale = sessionLocale; //update the locale
}
return dateFormat; //return the date format
}
/**
* Date style and time style constructor.
* @param dateStyle The date representation style, or null if the date should not be represented.
* @param timeStyle The time representation style, or null if the time should not be represented.
* @throws NullPointerException if both the given date style and time style are null.
*/
public AbstractDateStringLiteralConverter(final DateStringLiteralStyle dateStyle, final TimeStringLiteralStyle timeStyle) {
if(dateStyle == null && timeStyle == null) { //if neither a date style or a time style is specified
throw new NullPointerException("Either a date style or a time style must be specified.");
}
this.dateStyle = dateStyle;
this.timeStyle = timeStyle;
}
/**
* Creates a new date format object for the indicated styles and locale. This implementation does not allow both date and time styles to be specified if one
* of the styles specifies other than short/medium/long/full format.
* @param dateStyle The date representation style, or null if the date should not be represented.
* @param timeStyle The date representation style, or null if the date should not be represented.
* @param locale The locale for which a date format should be created.
* @param timeZone The time zone for which a date format should be created.
* @return A date format object appropriate for the given locale.
* @throws NullPointerException if the both the date style and time style is null, or if the locale and/or time zone is null.
* @throws IllegalArgumentException if both date style and time style is given and one of the styles specifies other than short/medium/long/full format.
*/
public static DateFormat createDateFormat(final DateStringLiteralStyle dateStyle, final TimeStringLiteralStyle timeStyle, final Locale locale,
final TimeZone timeZone) {
final int dateFormatStyle = dateStyle != null ? DATE_FORMAT_STYLES[dateStyle.ordinal()] : -1; //get the date format style
final int timeFormatStyle = timeStyle != null ? TIME_FORMAT_STYLES[timeStyle.ordinal()] : -1; //get the time format style
final DateFormat dateFormat; //we'll store here the date format
if(dateStyle != null) { //if a date style is requested
if(timeStyle != null) { //if both a date style and a time style is requested
if(dateFormatStyle < 0 || timeFormatStyle < 0) { //if one of the styles isn't a valid format style
throw new IllegalArgumentException("If both date style and style style are specified, each must be one of short/medium/long/full.");
}
dateFormat = DateFormat.getDateTimeInstance(dateFormatStyle, timeFormatStyle, locale); //create a date/time instance
} else { //if only a date style is requested
switch(dateStyle) {
case SHORT: //for the predefined format styles
case MEDIUM:
case LONG:
case FULL:
dateFormat = DateFormat.getDateInstance(dateFormatStyle, locale); //create a predefined date format instance
break;
case DAY_OF_WEEK:
dateFormat = new SimpleDateFormat("EEEE", locale); //get a day-of-week date format
break;
case DAY_OF_WEEK_SHORT:
dateFormat = new SimpleDateFormat("E", locale); //get a short day-of-week date format
break;
case MONTH_OF_YEAR:
dateFormat = new SimpleDateFormat("MMMM", locale); //get a month-of-year date format
break;
case MONTH_OF_YEAR_SHORT:
dateFormat = new SimpleDateFormat("M", locale); //get a short month-of-year date format
break;
default:
throw new AssertionError("Unrecognized date style: " + dateStyle);
}
}
} else { //if a date style is not requested, only a time style is requested
if(timeStyle != null) { //if only a time style is requested
dateFormat = DateFormat.getTimeInstance(timeFormatStyle, locale); //create a time instance
} else { //if neither a date style nor a time style is requested
throw new NullPointerException("Either a date style or a time style must be specified.");
}
}
//change the "yy" format to "yyyy" if possible
if(dateFormat instanceof SimpleDateFormat) { //if the new format is an instance of SimpleDateFormat TODO fix two-digit years for JVMs that do not return a SimpleDateFormat
final SimpleDateFormat simpleDateFormat = (SimpleDateFormat)dateFormat; //get the simple date format version
final String pattern = simpleDateFormat.toPattern(); //get the pattern being used
final int yyIndex = pattern.indexOf("yy"); //see if this pattern contains "yy" (i.e. the two-year designator)
if(yyIndex >= 0 && (yyIndex >= pattern.length() - 2 || pattern.charAt(yyIndex + 2) != 'y')) { //if there is only two 'y's in a row
final StringBuilder patternBuilder = new StringBuilder(pattern); //create a pattern builder to change the "yy" to "yyyy"
patternBuilder.insert(yyIndex, "yy"); //change the "yy" to "yyyy"
simpleDateFormat.applyPattern(patternBuilder.toString()); //apply the new pattern
}
}
dateFormat.setTimeZone(requireNonNull(timeZone, "Time zone cannot be null.")); //show that time zone to use for formatting the date and/or time
return dateFormat; //return the date format we created
}
/**
* Converts a value from a date value space to a literal value in the lexical space. This implementation converts the value using the date format object. This
* implementation synchronizes on the {@link DateFormat} instance.
* @param value The value in the value space to convert.
* @return The converted value in the lexical space, or null if the given literal is null..
* @throws ConversionException if the value cannot be converted.
* @see #getDateFormat()
*/
protected String convertDateValue(final Date value) throws ConversionException {
if(value != null) { //if there is a value
final DateFormat dateFormat = getDateFormat(); //get the date format to use
synchronized(dateFormat) { //don't allow other threads to access the date format object while we're using it
return dateFormat.format(value); //format the date
}
} else { //if there is no value
return null; //there's nothing to convert
}
}
/**
* Converts a literal representation of a value from the lexical space into a date value in the date value space. This implementation converts the empty
* string to a null value.
* @param literal The literal value in the lexical space to convert.
* @return The converted value in the value space, or null if the given literal is null.
* @throws ConversionException if the literal value cannot be converted.
*/
protected Date convertDateLiteral(final String literal) throws ConversionException {
if(literal != null && literal.length() > 0) { //if there is a literal value
final DateFormat dateFormat = getDateFormat(); //get the date format to use
final ParsePosition parsePosition = new ParsePosition(0); //create a new parse position
final Date date; //we'll store the date here
synchronized(dateFormat) { //don't allow other threads to access the date format object while we're using it
date = dateFormat.parse(literal, parsePosition); //parse the value, retrieving the parse positoin
}
if(parsePosition.getIndex() < literal.length()) { //if the whole string wasn't parsed, we'll consider that an error (either there was an error, in which case the index is zero, or part of the string was ignored)
throw new ConversionException(format(getSession().dereferenceString(getInvalidValueMessage()), literal), literal);
}
return date; //return the date we parsed
} else { //if there is no literal value
return null; //there is nothing to convert
}
}
/** Fills the date/time format style arrays for fast conversion from enumerated styles. */
static {
//fill the date format style array
final DateStringLiteralStyle[] dateStyles = DateStringLiteralStyle.values(); //get the available styles
for(int dateStyleIndex = dateStyles.length - 1; dateStyleIndex >= 0; --dateStyleIndex) { //for each style
int dateFormatStyle; //we'll determine the appropriate format style integer
final DateStringLiteralStyle dateStyle = dateStyles[dateStyleIndex]; //get this style
switch(dateStyle) { //see which style this is
case SHORT:
dateFormatStyle = DateFormat.SHORT;
break;
case MEDIUM:
dateFormatStyle = DateFormat.MEDIUM;
break;
case LONG:
dateFormatStyle = DateFormat.LONG;
break;
case FULL:
dateFormatStyle = DateFormat.FULL;
break;
default:
dateFormatStyle = -1; //indicate a style with no corresponding format style
break;
}
DATE_FORMAT_STYLES[dateStyleIndex] = dateFormatStyle; //save this date format style
}
//fill the time format style array
final TimeStringLiteralStyle[] timeStyles = TimeStringLiteralStyle.values(); //get the available styles
for(int timeStyleIndex = timeStyles.length - 1; timeStyleIndex >= 0; --timeStyleIndex) { //for each style
int timeFormatStyle; //we'll determine the appropriate format style integer
final TimeStringLiteralStyle timeStyle = timeStyles[timeStyleIndex]; //get this style
switch(timeStyle) { //see which style this is
case SHORT:
timeFormatStyle = DateFormat.SHORT;
break;
case MEDIUM:
timeFormatStyle = DateFormat.MEDIUM;
break;
case LONG:
timeFormatStyle = DateFormat.LONG;
break;
case FULL:
timeFormatStyle = DateFormat.FULL;
break;
default:
timeFormatStyle = -1; //indicate a style with no corresponding format style
break;
}
TIME_FORMAT_STYLES[timeStyleIndex] = timeFormatStyle; //save this time format style
}
}
}