org.b3log.latke.cron.Cron.java Source code

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Here is the source code for org.b3log.latke.cron.Cron.java

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/*
 * Copyright (c) 2009, 2010, 2011, 2012, B3log Team
 *
 * 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.b3log.latke.cron;

import java.net.URL;
import java.util.TimerTask;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.commons.lang.StringUtils;
import org.b3log.latke.servlet.HTTPRequestMethod;
import org.b3log.latke.urlfetch.HTTPRequest;
import org.b3log.latke.urlfetch.URLFetchService;
import org.b3log.latke.urlfetch.URLFetchServiceFactory;

/**
 * A cron job is a scheduled task, it will invoke {@link #url a URL} via an HTTP GET request, at a given time of day.
 * 
 * @author <a href="mailto:DL88250@gmail.com">Liang Ding</a>
 * @version 1.0.0.0, Apr 5, 2012
 */
public final class Cron extends TimerTask {

    /**
     * Logger.
     */
    private static final Logger LOGGER = Logger.getLogger(Cron.class.getName());
    /**
     * Time unit constant - 60.
     */
    public static final int SIXTY = 60;
    /**
     * Time unit constant - 1000.
     */
    public static final int THOUSAND = 1000;
    /**
     * The URL this cron job to invoke.
     */
    private String url;
    /**
     * Description of this cron job.
     */
    private String description;
    /**
     * Schedule of this cron job.
     * 
     * <p>
     * Available format: <em>every N (hours|minutes)</em>, for examples:
     * <ul>
     *   <li>every 12 hours</li>
     *   <li>every 10 minutes</li>
     * </ul>
     * </p>
     */
    private String schedule;
    /**
     * Time in milliseconds between successive task executions.
     */
    private long period;

    /**
     * Constructs a cron job with the specified URL, description and schedule.
     * 
     * @param url the specified URL
     * @param description the specified description
     * @param schedule the specified schedule
     */
    public Cron(final String url, final String description, final String schedule) {
        this.url = url;
        this.description = description;
        this.schedule = schedule;

        parse(schedule);
    }

    @Override
    public void run() {
        LOGGER.finer("Executing scheduled task....");

        final URLFetchService urlFetchService = URLFetchServiceFactory.getURLFetchService();

        final HTTPRequest request = new HTTPRequest();

        try {
            request.setURL(new URL(url));
            request.setRequestMethod(HTTPRequestMethod.GET);
            urlFetchService.fetchAsync(request);

            LOGGER.log(Level.FINER, "Executed scheduled task[url={0}]", url);
        } catch (final Exception e) {
            LOGGER.log(Level.SEVERE, "Scheduled task execute failed", e);

        }
    }

    /**
     * Parses the specified schedule into {@link #period execution period}.
     * 
     * @param schedule the specified schedule
     */
    private void parse(final String schedule) {
        final int num = Integer.valueOf(StringUtils.substringBetween(schedule, " ", " "));
        final String timeUnit = StringUtils.substringAfterLast(schedule, " ");

        LOGGER.log(Level.FINEST, "Parsed cron job[schedule={0}]: [num={1}, timeUnit={2}]",
                new Object[] { schedule, num, timeUnit });

        if ("hours".equals(timeUnit)) {
            period = num * SIXTY * SIXTY * THOUSAND;
        } else if ("minutes".equals(timeUnit)) {
            period = num * SIXTY * THOUSAND;
        }
    }

    /**
     * Gets the period.
     * 
     * @return period
     */
    public long getPeriod() {
        return period;
    }

    /**
     * Gets the description.
     * 
     * @return description
     */
    public String getDescription() {
        return description;
    }

    /**
     * Gets the schedule.
     * 
     * @return schedule
     */
    public String getSchedule() {
        return schedule;
    }

    /**
     * Gets the URL.
     * 
     * @return URL
     */
    public String getUrl() {
        return url;
    }

    /**
     * Sets the URL with the specified URL.
     * 
     * @param url the specified URL
     */
    public void setURL(final String url) {
        this.url = url;
    }
}