/*
* 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();
}
}
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