ColorJob.java

/* 
 * Copyright 2005 - 2009 Terracotta, Inc. 
 * 
 * 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.quartz.examples.example4;

import java.util.Date;

import org.quartz.DisallowConcurrentExecution;
import org.quartz.Job;
import org.quartz.JobDataMap;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import org.quartz.JobKey;
import org.quartz.PersistJobDataAfterExecution;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * <p>
 * This is just a simple job that receives parameters and
 * maintains state
 * </p>
 * 
 * @author Bill Kratzer
 */
@PersistJobDataAfterExecution
@DisallowConcurrentExecution
public class ColorJob implements Job {

    private static Logger _log = LoggerFactory.getLogger(ColorJob.class);
    
    // parameter names specific to this job
    public static final String FAVORITE_COLOR = "favorite color";
    public static final String EXECUTION_COUNT = "count";
    
    // Since Quartz will re-instantiate a class every time it
    // gets executed, members non-static member variables can
    // not be used to maintain state!
    private int _counter = 1;

    /**
     * <p>
     * Empty constructor for job initialization
     * </p>
     * <p>
     * Quartz requires a public empty constructor so that the
     * scheduler can instantiate the class whenever it needs.
     * </p>
     */
    public ColorJob() {
    }

    /**
     * <p>
     * Called by the <code>{@link org.quartz.Scheduler}</code> when a
     * <code>{@link org.quartz.Trigger}</code> fires that is associated with
     * the <code>Job</code>.
     * </p>
     * 
     * @throws JobExecutionException
     *             if there is an exception while executing the job.
     */
    public void execute(JobExecutionContext context)
        throws JobExecutionException {

        // This job simply prints out its job name and the
        // date and time that it is running
        JobKey jobKey = context.getJobDetail().getKey();
        
        // Grab and print passed parameters
        JobDataMap data = context.getJobDetail().getJobDataMap();
        String favoriteColor = data.getString(FAVORITE_COLOR);
        int count = data.getInt(EXECUTION_COUNT);
        _log.info("ColorJob: " + jobKey + " executing at " + new Date() + "\n" +
            "  favorite color is " + favoriteColor + "\n" + 
            "  execution count (from job map) is " + count + "\n" + 
            "  execution count (from job member variable) is " + _counter);
        
        // increment the count and store it back into the 
        // job map so that job state can be properly maintained
        count++;
        data.put(EXECUTION_COUNT, count);
        
        // Increment the local member variable 
        // This serves no real purpose since job state can not 
        // be maintained via member variables!
        _counter++;
    }

}