calendarbuilder.java

jcrontab是一个定时器开源项目包 目前提供存取文件或数据库, 把执行结果寄发 email, 简单地设置在 Tomcat, Resin, Jetty 及 JBoss 之上, 更是可以取代 cron

/**
 *  This file is part of the jcrontab package
 *  Copyright (C) 2001-2003 Israel Olalla
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *  MA 02111-1307, USA
 *
 *  For questions, suggestions:
 *
 *  [e-mail]
 *
 */
package org.jcrontab.data;

import java.util.Calendar;
import java.util.Date;
import java.util.Vector;
import java.util.Random;
import org.jcrontab.log.Log;

/** This class processes a CrontabEntryBean and returns a Calendar. This class 
 * is a "conversor" to convert from CrontabEntries to Calendars.
 * Thanks to Javier Pardo for the idea and for the Algorithm
 * @author $Author: iolalla $
 * @version $Revision: 1.7 $
 */

public class CalendarBuilder  {
    
    /**This method gets thes next CrontabEntry in the given Array. 
     * Yep i know this 
     * can be plural.... i mean not only one CrontabEntry but in this case 
     * we care only for one cause only need to know the next execution time.
     * @return CrontabEntryBean 
     * @param cebs CrontabEntryBean[]
     */
	
	public CrontabEntryBean getNextCrontabEntry(CrontabEntryBean[] cebs){
        long[] times = new long[cebs.length];
        int value = 0;
        
        int index = 0;
        
		for (int i = 0; i < cebs.length; i++) {
            times[i] = buildCalendar(cebs[i]).getTime();
		}
        
		long number = times[index];
        
		for (int i = 0 ; i < times.length ; i++) {
			if (times[i] < number ) {
                    number = times[i];
                    value = i;
           }
		}
		return cebs[value];
	}
    
	/**This method builds a Date from a CrontabEntryBean. launching the same 
     * method with now as parameter
     * @return Date 
     * @param ceb CrontabEntryBean
     */
	public Date buildCalendar(CrontabEntryBean ceb) {
		Date now = new Date(System.currentTimeMillis()); 
		return buildCalendar(ceb, now);
	}
	
	/**This method builds a Date from a CrontabEntryBean and from a starting 
     * Date
     * @return Date 
     * @param ceb CrontabEntryBean
     * @param afterDate Date
     */
	public Date buildCalendar(CrontabEntryBean ceb, Date afterDate) {
		Calendar after = Calendar.getInstance();
        after.setTime(afterDate);

		int second = getNextIndex(ceb.getBSeconds(), after.get(Calendar.SECOND));
        if (second == -1) {
            second = getNextIndex(ceb.getBSeconds(), 0);
            after.add(Calendar.MINUTE, 1);
        }
		
        int minute = getNextIndex(ceb.getBMinutes(), after.get(Calendar.MINUTE));
        if (minute == -1) {
			second = getNextIndex(ceb.getBSeconds(), 0);
            minute = getNextIndex(ceb.getBMinutes(), 0);
            after.add(Calendar.HOUR_OF_DAY, 1);
        }

        int hour = getNextIndex(ceb.getBHours(), after.get(Calendar.HOUR_OF_DAY));
        if (hour == -1) {
			second = getNextIndex(ceb.getBSeconds(), 0);
            minute = getNextIndex(ceb.getBMinutes(), 0);
            hour = getNextIndex(ceb.getBHours(), 0);
            after.add(Calendar.DAY_OF_MONTH, 1);
        }

        int dayOfMonth = getNextIndex(ceb.getBDaysOfMonth(), after.get(Calendar.DAY_OF_MONTH) - 1);
        
        
        if (dayOfMonth == -1) {
			second = getNextIndex(ceb.getBSeconds(), 0);
            minute = getNextIndex(ceb.getBMinutes(), 0);
            hour = getNextIndex(ceb.getBHours(), 0);
            dayOfMonth = getNextIndex(ceb.getBDaysOfMonth(), 0);
            after.add(Calendar.MONTH, 1);
        }

        boolean dayMatchRealDate = false;
        while (!dayMatchRealDate) {
            if (checkDayValidInMonth(dayOfMonth + 1, after.get(Calendar.MONTH),
                            after.get(Calendar.YEAR))) {
                dayMatchRealDate = true;
            } else {
                after.add(Calendar.MONTH, 1);
            }
        }
        
        int month = getNextIndex(ceb.getBMonths(), after.get(Calendar.MONTH));
        if (month == -1) {
			second = getNextIndex(ceb.getBSeconds(), 0);
            minute = getNextIndex(ceb.getBMinutes(), 0);
            hour = getNextIndex(ceb.getBHours(), 0);
            dayOfMonth = getNextIndex(ceb.getBDaysOfMonth(), 0);
            month = getNextIndex(ceb.getBMonths(), 0);
            after.add(Calendar.YEAR, 1);
        }

        Date byMonthDays = getTime(second, minute, hour, dayOfMonth + 1,
                       month, after.get(Calendar.YEAR));
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(byMonthDays);

		boolean[] bDaysOfWeek = ceb.getBDaysOfWeek();
		
         if (bDaysOfWeek[calendar.get(Calendar.DAY_OF_WEEK) - 1]) {
             return calendar.getTime();
         } else {
             calendar.add(Calendar.DAY_OF_YEAR, 1);
             return buildCalendar(ceb , calendar.getTime());
         }
	}
	/**This method builds a Date from a CrontabEntryBean and from a starting 
     * Date
     * @return Date builded with those parameters
     * @param sedonds int the seconds of this time
     * @param minutes int the minutes of this time 
     * @param hour int the hour of this time 
     * @param dayOfMonth int the dayOfMonth of this time 
     * @param month int the month of this time 
     * @param year int the year of this time 
     * @param afterDate Date
     */
    private Date getTime(int seconds,
                         int minutes,
                         int hour,
                         int dayOfMonth,
                         int month,
                         int year) {
        try {
            Calendar cl = Calendar.getInstance();
            cl.set(year, month, dayOfMonth, hour, minutes, seconds);
            return cl.getTime();
        } catch (Exception e) {
            Log.error("Smth was wrong:", e);
            return null;
        }
    }
    
    /**
     * This method says wich is next index of this array
     * @param array the list of booleans to check
     * @param start int the id where starts the search
     * @return index int
     */
    private int getNextIndex(boolean[] array, int start) {
        for (int i = start; i < array.length; i++) {
            if (array[i]) return i;
        }
        return -1;
    }
    /** 
     * This says if this month has this day or not, basically this problem
     * occurrs with 31 days in months with less days.
     * @thanks to Javier Pardo :-)
     * @param day int the day so see if exists or not
     * @param month int the month to see it has this day or not.
     * @param year to see if valid ... to work with 366 days years and February 
     * :-)
     */
    private boolean checkDayValidInMonth(int day, int month, int year) {
        try {
            Calendar cl = Calendar.getInstance();
            cl.setLenient(false);
            cl.set(Calendar.DAY_OF_MONTH, day);
            cl.set(Calendar.MONTH, month);
            cl.set(Calendar.YEAR, year);
            cl.getTime();
        } catch (IllegalArgumentException e) {
            return false;
        }
        return true;
    }
}