/* * Copyright 2002-2010 the original author or authors. * * 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.springframework.scheduling.support; import java.util.Date; import java.util.TimeZone; import org.springframework.scheduling.Trigger; import org.springframework.scheduling.TriggerContext; /** * {@link Trigger} implementation for cron expressions. * Wraps a {@link CronSequenceGenerator}. * * @author Juergen Hoeller * @since 3.0 * @see CronSequenceGenerator */ public class CronTrigger implements Trigger { private final CronSequenceGenerator sequenceGenerator; /** * Build a {@link CronTrigger} from the pattern provided in the default time zone. * @param cronExpression a space-separated list of time fields, * following cron expression conventions */ public CronTrigger(String cronExpression) { this(cronExpression, TimeZone.getDefault()); } /** * Build a {@link CronTrigger} from the pattern provided. * @param cronExpression a space-separated list of time fields, * following cron expression conventions * @param timeZone a time zone in which the trigger times will be generated */ public CronTrigger(String cronExpression, TimeZone timeZone) { this.sequenceGenerator = new CronSequenceGenerator(cronExpression, timeZone); } public Date nextExecutionTime(TriggerContext triggerContext) { Date date = triggerContext.lastCompletionTime(); if (date != null) { Date scheduled = triggerContext.lastScheduledExecutionTime(); if (scheduled != null && date.before(scheduled)) { // Previous task apparently executed too early... // Let's simply use the last calculated execution time then, // in order to prevent accidental re-fires in the same second. date = scheduled; } } else { date = new Date(); } return this.sequenceGenerator.next(date); } @Override public boolean equals(Object obj) { return (this == obj || (obj instanceof CronTrigger && this.sequenceGenerator.equals(((CronTrigger) obj).sequenceGenerator))); } @Override public int hashCode() { return this.sequenceGenerator.hashCode(); } @Override public String toString() { return sequenceGenerator.toString(); } }