001    // Copyright 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.ioc.services.cron;
016    
017    import org.apache.tapestry5.ioc.internal.services.cron.CronExpression;
018    
019    import java.text.ParseException;
020    import java.util.Date;
021    
022    public class CronSchedule implements Schedule
023    {
024        private CronExpression cron;
025    
026        public CronSchedule(String cronExpression)
027        {
028            try
029            {
030                this.cron = new CronExpression(cronExpression);
031            } catch (ParseException e)
032            {
033                throw new RuntimeException(e);
034            }
035        }
036    
037        public long firstExecution()
038        {
039            return getNextValidTimeAfterNow();
040        }
041    
042        public long nextExecution(long previousExecution)
043        {
044            return getNextValidTimeAfterNow();
045        }
046    
047        private long getNextValidTimeAfterNow()
048        {
049            final Date time = cron.getNextValidTimeAfter(new Date());
050    
051            return time == null ? 0 : time.getTime();
052        }
053    }