Mega Code Archive
Date Format Cache
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//
// Copyright 2004-2005 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
import java.text.DateFormatSymbols;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
/* ------------------------------------------------------------ */
/** Date Format Cache.
* Computes String representations of Dates and caches
* the results so that subsequent requests within the same minute
* will be fast.
*
* Only format strings that contain either "ss" or "ss.SSS" are
* handled.
*
* The timezone of the date may be included as an ID with the "zzz"
* format string or as an offset with the "ZZZ" format string.
*
* If consecutive calls are frequently very different, then this
* may be a little slower than a normal DateFormat.
*
* @author Kent Johnson <KJohnson@transparent.com>
* @author Greg Wilkins (gregw)
*/
public class DateCache
{
private static long __hitWindow=60*60;
private static long __MaxMisses=10;
private String _formatString;
private String _tzFormatString;
private SimpleDateFormat _tzFormat;
private String _minFormatString;
private SimpleDateFormat _minFormat;
private String _secFormatString;
private String _secFormatString0;
private String _secFormatString1;
private boolean _millis=false;
private long _misses = 0;
private long _lastMinutes = -1;
private long _lastSeconds = -1;
private String _lastResult = null;
private Locale _locale = null;
private DateFormatSymbols _dfs = null;
/* ------------------------------------------------------------ */
/** Constructor.
* Make a DateCache that will use a default format. The default format
* generates the same results as Date.toString().
*/
public DateCache()
{
this("EEE MMM dd HH:mm:ss zzz yyyy");
getFormat().setTimeZone(TimeZone.getDefault());
}
/* ------------------------------------------------------------ */
/** Constructor.
* Make a DateCache that will use the given format
*/
public DateCache(String format)
{
_formatString=format;
setTimeZone(TimeZone.getDefault());
}
/* ------------------------------------------------------------ */
public DateCache(String format,Locale l)
{
_formatString=format;
_locale = l;
setTimeZone(TimeZone.getDefault());
}
/* ------------------------------------------------------------ */
public DateCache(String format,DateFormatSymbols s)
{
_formatString=format;
_dfs = s;
setTimeZone(TimeZone.getDefault());
}
/* ------------------------------------------------------------ */
/** Set the timezone.
* @param tz TimeZone
*/
public void setTimeZone(TimeZone tz)
{
setTzFormatString(tz);
if( _locale != null )
{
_tzFormat=new SimpleDateFormat(_tzFormatString,_locale);
_minFormat=new SimpleDateFormat(_minFormatString,_locale);
}
else if( _dfs != null )
{
_tzFormat=new SimpleDateFormat(_tzFormatString,_dfs);
_minFormat=new SimpleDateFormat(_minFormatString,_dfs);
}
else
{
_tzFormat=new SimpleDateFormat(_tzFormatString);
_minFormat=new SimpleDateFormat(_minFormatString);
}
_tzFormat.setTimeZone(tz);
_minFormat.setTimeZone(tz);
_lastSeconds=-1;
_lastMinutes=-1;
}
/* ------------------------------------------------------------ */
public TimeZone getTimeZone()
{
return _tzFormat.getTimeZone();
}
/* ------------------------------------------------------------ */
/** Set the timezone.
* @param timeZoneId TimeZoneId the ID of the zone as used by
* TimeZone.getTimeZone(id)
*/
public void setTimeZoneID(String timeZoneId)
{
setTimeZone(TimeZone.getTimeZone(timeZoneId));
}
/* ------------------------------------------------------------ */
private void setTzFormatString(final TimeZone tz )
{
int zIndex = _formatString.indexOf( "ZZZ" );
if( zIndex >= 0 )
{
String ss1 = _formatString.substring( 0, zIndex );
String ss2 = _formatString.substring( zIndex+3 );
int tzOffset = tz.getRawOffset();
StringBuffer sb = new StringBuffer(_formatString.length()+10);
sb.append(ss1);
sb.append("'");
if( tzOffset >= 0 )
sb.append( '+' );
else
{
tzOffset = -tzOffset;
sb.append( '-' );
}
int raw = tzOffset / (1000*60); // Convert to seconds
int hr = raw / 60;
int min = raw % 60;
if( hr < 10 )
sb.append( '0' );
sb.append( hr );
if( min < 10 )
sb.append( '0' );
sb.append( min );
sb.append( '\'' );
sb.append(ss2);
_tzFormatString=sb.toString();
}
else
_tzFormatString=_formatString;
setMinFormatString();
}
/* ------------------------------------------------------------ */
private void setMinFormatString()
{
int i = _tzFormatString.indexOf("ss.SSS");
int l = 6;
if (i>=0)
_millis=true;
else
{
i = _tzFormatString.indexOf("ss");
l=2;
}
// Build a formatter that formats a second format string
// Have to replace @ with ' later due to bug in SimpleDateFormat
String ss1=_tzFormatString.substring(0,i);
String ss2=_tzFormatString.substring(i+l);
_minFormatString =ss1+(_millis?"'ss.SSS'":"'ss'")+ss2;
}
/* ------------------------------------------------------------ */
/** Format a date according to our stored formatter.
* @param inDate
* @return Formatted date
*/
public synchronized String format(Date inDate)
{
return format(inDate.getTime());
}
/* ------------------------------------------------------------ */
/** Format a date according to our stored formatter.
* @param inDate
* @return Formatted date
*/
public synchronized String format(long inDate)
{
long seconds = inDate / 1000;
// Is it not suitable to cache?
if (seconds<_lastSeconds ||
_lastSeconds>0 && seconds>_lastSeconds+__hitWindow)
{
// It's a cache miss
_misses++;
if (_misses<__MaxMisses)
{
Date d = new Date(inDate);
return _tzFormat.format(d);
}
}
else if (_misses>0)
_misses--;
// Check if we are in the same second
// and don't care about millis
if (_lastSeconds==seconds && !_millis)
return _lastResult;
Date d = new Date(inDate);
// Check if we need a new format string
long minutes = seconds/60;
if (_lastMinutes != minutes)
{
_lastMinutes = minutes;
_secFormatString=_minFormat.format(d);
int i;
int l;
if (_millis)
{
i=_secFormatString.indexOf("ss.SSS");
l=6;
}
else
{
i=_secFormatString.indexOf("ss");
l=2;
}
_secFormatString0=_secFormatString.substring(0,i);
_secFormatString1=_secFormatString.substring(i+l);
}
// Always format if we get here
_lastSeconds = seconds;
StringBuffer sb=new StringBuffer(_secFormatString.length());
synchronized(sb)
{
sb.append(_secFormatString0);
int s=(int)(seconds%60);
if (s<10)
sb.append('0');
sb.append(s);
if (_millis)
{
long millis = inDate%1000;
if (millis<10)
sb.append(".00");
else if (millis<100)
sb.append(".0");
else
sb.append('.');
sb.append(millis);
}
sb.append(_secFormatString1);
_lastResult=sb.toString();
}
return _lastResult;
}
/* ------------------------------------------------------------ */
/** Format to string buffer.
* @param inDate Date the format
* @param buffer StringBuffer
*/
public void format(long inDate, StringBuffer buffer)
{
buffer.append(format(inDate));
}
/* ------------------------------------------------------------ */
/** Get the format.
*/
public SimpleDateFormat getFormat()
{
return _minFormat;
}
/* ------------------------------------------------------------ */
public String getFormatString()
{
return _formatString;
}
/* ------------------------------------------------------------ */
public String now()
{
return format(System.currentTimeMillis());
}
}
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