001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.scheduling.annotation;
018
019import java.lang.annotation.Documented;
020import java.lang.annotation.ElementType;
021import java.lang.annotation.Repeatable;
022import java.lang.annotation.Retention;
023import java.lang.annotation.RetentionPolicy;
024import java.lang.annotation.Target;
025
026/**
027 * An annotation that marks a method to be scheduled. Exactly one of
028 * the {@link #cron()}, {@link #fixedDelay()}, or {@link #fixedRate()}
029 * attributes must be specified.
030 *
031 * <p>The annotated method must expect no arguments. It will typically have
032 * a {@code void} return type; if not, the returned value will be ignored
033 * when called through the scheduler.
034 *
035 * <p>Processing of {@code @Scheduled} annotations is performed by
036 * registering a {@link ScheduledAnnotationBeanPostProcessor}. This can be
037 * done manually or, more conveniently, through the {@code <task:annotation-driven/>}
038 * element or @{@link EnableScheduling} annotation.
039 *
040 * <p>This annotation may be used as a <em>meta-annotation</em> to create custom
041 * <em>composed annotations</em> with attribute overrides.
042 *
043 * @author Mark Fisher
044 * @author Juergen Hoeller
045 * @author Dave Syer
046 * @author Chris Beams
047 * @since 3.0
048 * @see EnableScheduling
049 * @see ScheduledAnnotationBeanPostProcessor
050 * @see Schedules
051 */
052@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
053@Retention(RetentionPolicy.RUNTIME)
054@Documented
055@Repeatable(Schedules.class)
056public @interface Scheduled {
057
058        /**
059         * A cron-like expression, extending the usual UN*X definition to include triggers
060         * on the second as well as minute, hour, day of month, month and day of week.
061         * <p>E.g. {@code "0 * * * * MON-FRI"} means once per minute on weekdays
062         * (at the top of the minute - the 0th second).
063         * @return an expression that can be parsed to a cron schedule
064         * @see org.springframework.scheduling.support.CronSequenceGenerator
065         */
066        String cron() default "";
067
068        /**
069         * A time zone for which the cron expression will be resolved. By default, this
070         * attribute is the empty String (i.e. the server's local time zone will be used).
071         * @return a zone id accepted by {@link java.util.TimeZone#getTimeZone(String)},
072         * or an empty String to indicate the server's default time zone
073         * @since 4.0
074         * @see org.springframework.scheduling.support.CronTrigger#CronTrigger(String, java.util.TimeZone)
075         * @see java.util.TimeZone
076         */
077        String zone() default "";
078
079        /**
080         * Execute the annotated method with a fixed period in milliseconds between the
081         * end of the last invocation and the start of the next.
082         * @return the delay in milliseconds
083         */
084        long fixedDelay() default -1;
085
086        /**
087         * Execute the annotated method with a fixed period in milliseconds between the
088         * end of the last invocation and the start of the next.
089         * @return the delay in milliseconds as a String value, e.g. a placeholder
090         * @since 3.2.2
091         */
092        String fixedDelayString() default "";
093
094        /**
095         * Execute the annotated method with a fixed period in milliseconds between
096         * invocations.
097         * @return the period in milliseconds
098         */
099        long fixedRate() default -1;
100
101        /**
102         * Execute the annotated method with a fixed period in milliseconds between
103         * invocations.
104         * @return the period in milliseconds as a String value, e.g. a placeholder
105         * @since 3.2.2
106         */
107        String fixedRateString() default "";
108
109        /**
110         * Number of milliseconds to delay before the first execution of a
111         * {@link #fixedRate()} or {@link #fixedDelay()} task.
112         * @return the initial delay in milliseconds
113         * @since 3.2
114         */
115        long initialDelay() default -1;
116
117        /**
118         * Number of milliseconds to delay before the first execution of a
119         * {@link #fixedRate()} or {@link #fixedDelay()} task.
120         * @return the initial delay in milliseconds as a String value, e.g. a placeholder
121         * @since 3.2.2
122         */
123        String initialDelayString() default "";
124
125}