org.x4juli.formatter.pattern
Class CachedDateFormat

java.lang.Object
  java.text.Format
      java.text.DateFormat
          org.x4juli.formatter.pattern.CachedDateFormat

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

public class CachedDateFormat

extends java.text.DateFormat

CachedDateFormat optimizes the performance of a wrapped DateFormat. The implementation is not thread-safe. If the millisecond pattern is not recognized, the class will only use the cache if the same value is requested.

Logging API as a whole was originally done for Apache log4j. Juli is a port of main parts of that to complete the Java Logging APIs. All credits for initial idea, design, implementation, documentation belong to the log4j crew. This file was originally published by Curt Arnold. Please use exclusively the appropriate mailing lists for questions, remarks and contribution.

Since:

0.5

Author:

Boris Unckel

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class java.text.DateFormat

java.text.DateFormat.Field

Nested classes inherited from class java.text.Format

Field Summary

private java.lang.StringBuffer	cache Cache of previous conversion.
private static java.lang.String	DIGITS Supported digit set.
private int	expiration Maximum validity period for the cache.
private java.text.DateFormat	formatter Wrapped formatter.
private static int	MAGIC1 First magic number used to detect the millisecond position.
private static int	MAGIC2 Second magic number used to detect the millisecond position.
private static java.lang.String	MAGICSTRING1 Expected representation of first magic number.
private static java.lang.String	MAGICSTRING2 Expected representation of second magic number.
private int	millisecondStart Index of initial digit of millisecond pattern or UNRECOGNIZED_MILLISECONDS or NO_MILLISECONDS.
static int	NO_MILLISECONDS Constant used to represent that there was no change observed when changing the millisecond count.
private static int	ONE_HUNDRED
private static int	ONE_THOUSAND
private static long	ONE_THOUSAND_L
private long	previousTime Date requested in previous conversion.
private static long	serialVersionUID
private long	slotBegin Integral second preceding the previous convered Date.
private static int	TEN
private java.util.Date	tmpDate Scratch date object used to minimize date object creation.
static int	UNRECOGNIZED_MILLISECONDS Constant used to represent that there was an observed change, but was an expected change.
private static java.lang.String	ZERO_STRING Expected representation of 0 milliseconds.

Fields inherited from class java.text.DateFormat

AM_PM_FIELD, calendar, DATE_FIELD, DAY_OF_WEEK_FIELD, DAY_OF_WEEK_IN_MONTH_FIELD, DAY_OF_YEAR_FIELD, DEFAULT, ERA_FIELD, FULL, HOUR_OF_DAY0_FIELD, HOUR_OF_DAY1_FIELD, HOUR0_FIELD, HOUR1_FIELD, LONG, MEDIUM, MILLISECOND_FIELD, MINUTE_FIELD, MONTH_FIELD, numberFormat, SECOND_FIELD, SHORT, TIMEZONE_FIELD, WEEK_OF_MONTH_FIELD, WEEK_OF_YEAR_FIELD, YEAR_FIELD

Constructor Summary

CachedDateFormat(java.text.DateFormat dateFormat, int expiration)
Creates a new CachedDateFormat object.

Method Summary

static int	findMillisecondStart(long time, java.lang.String formatted, java.text.DateFormat formatter) Finds start of millisecond field in formatted time.
java.lang.StringBuffer	format(java.util.Date date, java.lang.StringBuffer sbuf, java.text.FieldPosition fieldPosition) Formats a Date into a date/time string.
java.lang.StringBuffer	format(long now, java.lang.StringBuffer buf) Formats a millisecond count into a date/time string.
static int	getMaximumCacheValidity(java.lang.String pattern) Gets maximum cache validity for the specified SimpleDateTime conversion pattern.
java.text.NumberFormat	getNumberFormat() Gets number formatter.
private static void	millisecondFormat(int millis, java.lang.StringBuffer buf, int offset) Formats a count of milliseconds (0-999) into a numeric representation.
java.util.Date	parse(java.lang.String s, java.text.ParsePosition pos) This method is delegated to the formatter which most likely returns null.
void	setTimeZone(java.util.TimeZone timeZone) Set timezone.
java.lang.String	toString()

Methods inherited from class java.text.DateFormat

clone, equals, format, format, getAvailableLocales, getCalendar, getDateInstance, getDateInstance, getDateInstance, getDateTimeInstance, getDateTimeInstance, getDateTimeInstance, getInstance, getTimeInstance, getTimeInstance, getTimeInstance, getTimeZone, hashCode, isLenient, parse, parseObject, setCalendar, setLenient, setNumberFormat

Methods inherited from class java.text.Format

format, formatToCharacterIterator, parseObject

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NO_MILLISECONDS

public static final int NO_MILLISECONDS

Constant used to represent that there was no change observed when changing the millisecond count.
Value is -2.

See Also:

Constant Field Values

UNRECOGNIZED_MILLISECONDS

public static final int UNRECOGNIZED_MILLISECONDS

Constant used to represent that there was an observed change, but was an expected change.
Value is -1.

See Also:

Constant Field Values

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

TEN

private static final int TEN

See Also:

Constant Field Values

ONE_HUNDRED

private static final int ONE_HUNDRED

See Also:

Constant Field Values

ONE_THOUSAND_L

private static final long ONE_THOUSAND_L

See Also:

Constant Field Values

ONE_THOUSAND

private static final int ONE_THOUSAND

See Also:

Constant Field Values

DIGITS

private static final java.lang.String DIGITS

Supported digit set. If the wrapped DateFormat uses a different unit set, the millisecond pattern will not be recognized and duplicate requests will use the cache.

See Also:

Constant Field Values

MAGIC1

private static final int MAGIC1

First magic number used to detect the millisecond position.

See Also:

Constant Field Values

MAGICSTRING1

private static final java.lang.String MAGICSTRING1

Expected representation of first magic number.

See Also:

Constant Field Values

MAGIC2

private static final int MAGIC2

Second magic number used to detect the millisecond position.

See Also:

Constant Field Values

MAGICSTRING2

private static final java.lang.String MAGICSTRING2

Expected representation of second magic number.

See Also:

Constant Field Values

ZERO_STRING

private static final java.lang.String ZERO_STRING

Expected representation of 0 milliseconds.

See Also:

Constant Field Values

formatter

private final java.text.DateFormat formatter

Wrapped formatter.

millisecondStart

private int millisecondStart

Index of initial digit of millisecond pattern or UNRECOGNIZED_MILLISECONDS or NO_MILLISECONDS.

slotBegin

private long slotBegin

Integral second preceding the previous convered Date.

cache

private java.lang.StringBuffer cache

Cache of previous conversion.

expiration

private final int expiration

Maximum validity period for the cache. Typically 1, use cache for duplicate requests only, or 1000, use cache for requests within the same integral second.

previousTime

private long previousTime

Date requested in previous conversion.

tmpDate

private final java.util.Date tmpDate

Scratch date object used to minimize date object creation.

Constructor Detail

CachedDateFormat

public CachedDateFormat(java.text.DateFormat dateFormat,
                        int expiration)

Creates a new CachedDateFormat object.

Parameters:

dateFormat - Date format, may not be null.

expiration - maximum cached range in milliseconds. If the dateFormat is known to be incompatible with the caching algorithm, use a value of 0 to totally disable caching or 1 to only use cache for duplicate requests.

Since:

0.5

Method Detail

findMillisecondStart

public static int findMillisecondStart(long time,
                                       java.lang.String formatted,
                                       java.text.DateFormat formatter)

Finds start of millisecond field in formatted time.

Parameters:

time - long time, must be integral number of seconds

formatted - String corresponding formatted string

formatter - DateFormat date format

Returns:

int position in string of first digit of milliseconds, -1 indicates no millisecond field, -2 indicates unrecognized field (likely RelativeTimeDateFormat)

Since:

0.5

format

public java.lang.StringBuffer format(java.util.Date date,
                                     java.lang.StringBuffer sbuf,
                                     java.text.FieldPosition fieldPosition)

Formats a Date into a date/time string.

Parameters:

date - the date to format.

sbuf - the string buffer to write to.

fieldPosition - remains untouched.

Returns:

the formatted time string.

Since:

0.5

format

public java.lang.StringBuffer format(long now,
                                     java.lang.StringBuffer buf)

Formats a millisecond count into a date/time string.

Parameters:

now - Number of milliseconds after midnight 1 Jan 1970 GMT.

buf - the string buffer to write to.

Returns:

the formatted time string.

Since:

0.5

millisecondFormat

private static void millisecondFormat(int millis,
                                      java.lang.StringBuffer buf,
                                      int offset)

Formats a count of milliseconds (0-999) into a numeric representation.

Parameters:

millis - Millisecond coun between 0 and 999.

buf - String buffer, may not be null.

offset - Starting position in buffer, the length of the buffer must be at least offset + 3.

Since:

0.5

setTimeZone

public void setTimeZone(java.util.TimeZone timeZone)

Set timezone. Setting the timezone using getCalendar().setTimeZone() will likely cause caching to misbehave.

Parameters:

timeZone - TimeZone new timezone

Since:

0.5

parse

public java.util.Date parse(java.lang.String s,
                            java.text.ParsePosition pos)

This method is delegated to the formatter which most likely returns null.

Parameters:

s - string representation of date.

pos - field position, unused.

Returns:

parsed date, likely null.

Since:

0.5

getNumberFormat

public java.text.NumberFormat getNumberFormat()

Gets number formatter.

Returns:

NumberFormat number formatter

Since:

0.5

getMaximumCacheValidity

public static int getMaximumCacheValidity(java.lang.String pattern)

Gets maximum cache validity for the specified SimpleDateTime conversion pattern.

Parameters:

pattern - conversion pattern, may not be null.

Returns:

Duration in milliseconds from an integral second that the cache will return consistent results.

Since:

0.5

toString

public java.lang.String toString()

Since:

0.5