Jetty example source code file (DateCache.java)

This example Jetty source code file (DateCache.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Jetty tags/keywords

date, date, datecache, datecache, default_format, eee, hh:mm:ss, mmm, simpledateformat, simpledateformat, string, string, stringbuffer, text, timezone, util

The Jetty DateCache.java source code

// ========================================================================
// 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.
// ========================================================================

package org.mortbay.util;

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  
{
    public static String DEFAULT_FORMAT="EEE MMM dd HH:mm:ss zzz yyyy";
    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 long _lastMinutes = -1;
    private long _lastSeconds = -1;
    private int _lastMs = -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(DEFAULT_FORMAT);
        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)
            throw new IllegalStateException("ms not supported");
        i = _tzFormatString.indexOf("ss");
        l=2;
        
        // Build a formatter that formats a second format string
        String ss1=_tzFormatString.substring(0,i);
        String ss2=_tzFormatString.substring(i+l);
        _minFormatString =ss1+"'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
            Date d = new Date(inDate);
            return _tzFormat.format(d);
            
        }
                                          
        // Check if we are in the same second
        // and don't care about millis
        if (_lastSeconds==seconds )
            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=_secFormatString.indexOf("ss");
            int 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);
            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()
    {
        long now=System.currentTimeMillis();
        int n=0xfff&(int)now;
        _lastMs=n%1000;
        return format(now);
    }

    /* ------------------------------------------------------------ */
    public int lastMs()
    {
        return _lastMs;
    }
}