Adding Trigger interface and the IntervalTrigger and CronTrigger implementations.

org.springframework.integration/src/main/java/org/springframework/integration/scheduling/CronTrigger.java

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+/*
+ * Copyright 2002-2008 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.integration.scheduling;
+
+import java.text.ParseException;
+import java.util.Date;
+
+import org.quartz.CronExpression;
+
+import org.springframework.integration.ConfigurationException;
+
+/**
+ * A trigger that uses a cron expression.
+ * 
+ * @author Mark Fisher
+ */
+public class CronTrigger implements Trigger {
+
+	private final CronExpression expression;
+
+
+	/**
+	 * Create a trigger for the given cron expression.
+	 */
+	public CronTrigger(String expression) {
+		try {
+			this.expression = new CronExpression(expression);
+		} catch (ParseException e) {
+			throw new ConfigurationException(
+					"failed to parse cron expression: " + expression);
+		}
+	}
+
+
+	/**
+	 * Return the next time a task should run. Determined by this trigger's
+	 * cron expression.
+	 */
+	public Date getNextRunTime(Date lastScheduledRunTime, Date lastCompleteTime) {
+		return this.expression.getNextValidTimeAfter(new Date());
+	}
+
+}

org.springframework.integration/src/main/java/org/springframework/integration/scheduling/IntervalTrigger.java

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+/*
+ * Copyright 2002-2008 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.integration.scheduling;
+
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.util.Assert;
+
+/**
+ * A trigger for periodic execution. The interval may be applied as either
+ * fixed-rate or fixed-delay, and an initial delay value may also be
+ * configured. The default initial delay is 0, and the default behavior is
+ * fixed-delay: each subsequent delay is measured from the last completion
+ * time. To enable execution between the scheduled start time of each
+ * execution, set 'fixedRate' to true.
+ * 
+ * @author Mark Fisher
+ */
+public class IntervalTrigger implements Trigger {
+
+	private final long interval;
+
+	private volatile long initialDelay = 0;
+
+	private volatile boolean fixedRate = false;
+
+
+	/**
+	 * Create a trigger with the given interval in milliseconds.
+	 */
+	public IntervalTrigger(long interval) {
+		Assert.isTrue(interval >= 0, "interval must not be negative");
+		this.interval = interval;
+	}
+
+	/**
+	 * Create a trigger with the given interval and time unit.
+	 */
+	public IntervalTrigger(long interval, TimeUnit unit) {
+		this(unit.toMillis(interval));
+	}
+
+
+	/**
+	 * Specify the delay for the initial execution.
+	 */
+	public void setInitialDelay(long initialDelay) {
+		this.initialDelay = initialDelay;
+	}
+
+	/**
+	 * Specify whether the interval should be measured between the
+	 * scheduled start times rather than between actual completion times
+	 * (the latter, "fixed delay" behavior, is the default).
+	 */
+	public void setFixedRate(boolean fixedRate) {
+		this.fixedRate = fixedRate;
+	}
+
+	/**
+	 * Returns the next time a task should run.
+	 */
+	public Date getNextRunTime(Date lastScheduledRunTime, Date lastCompleteTime) {
+		if (lastScheduledRunTime == null) {
+			return new Date(System.currentTimeMillis() + this.initialDelay);
+		}
+		else if (this.fixedRate) {
+			return new Date(lastScheduledRunTime.getTime() + this.interval);
+		}
+		return new Date(lastCompleteTime.getTime() + this.interval);
+	}
+
+}

org.springframework.integration/src/main/java/org/springframework/integration/scheduling/Trigger.java

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+/*
+ * Copyright 2002-2008 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.integration.scheduling;
+
+import java.util.Date;
+
+/**
+ * A strategy for providing the next time a task should run.
+ *
+ * @author Mark Fisher
+ */
+public interface Trigger {
+
+	/**
+	 * Returns the next time that a task should run or <code>null</code> if the
+	 * task should not run again.
+	 * 
+	 * @param lastScheduledRunTime last time the relevant task was scheduled to
+	 * run, or <code>null</code> if it has never been scheduled
+	 * @param lastCompleteTime last time the relevant task finished or
+	 * <code>null</code> if it did not run to completion
+	 * @return next time that a task should run
+	 */
+	public Date getNextRunTime(Date lastScheduledRunTime, Date lastCompleteTime);
+
+}