Quartz Scheduler 任务参数与任务状态

@DisallowConcurrentExecution

此标记用在实现Job的类上面,意思是不允许并发执行,按照我之前的理解是 不允许调度框架在同一时刻调用Job类，后来经过测试发现并不是这样，而是Job(任务)的执行时间[比如需要10秒]大于任务的时间间隔[Interval（5秒)],那么默认情况下,调度框架为了能让 任务按照我们预定的时间间隔执行,会马上启用新的线程执行任务。否则的话会等待任务执行完毕以后 再重新执行！（这样会导致任务的执行不是按照我们预先定义的时间间隔执行）

测试代码，这是官方提供的例子。设定的时间间隔为3秒,但job执行时间是5秒,设置@DisallowConcurrentExecution以后程序会等任务执行完毕以后再去执行,否则会在3秒时再启用新的线程执行

org.quartz.threadPool.threadCount = 5 这里配置框架的线程池中线程的数量,要多配置几个,否则@DisallowConcurrentExecution不起作用

org.quartz.scheduler.instanceName = MyScheduler
org.quartz.threadPool.threadCount = 5
org.quartz.jobStore.class =org.quartz.simpl.RAMJobStore

/* 
 * 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.example5;

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.PersistJobDataAfterExecution;

/**
 * <p>
 * A dumb implementation of Job, for unit testing purposes.
 * </p>
 * 
 * @author James House
 */
@PersistJobDataAfterExecution
@DisallowConcurrentExecution
public class StatefulDumbJob implements Job {

    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Constants.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    public static final String NUM_EXECUTIONS = "NumExecutions";

    public static final String EXECUTION_DELAY = "ExecutionDelay";

    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Constructors.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    public StatefulDumbJob() {
    }

    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Interface.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    /**
     * <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 {
        System.err.println("---" + context.getJobDetail().getKey()
                + " executing.[" + new Date() + "]");

        JobDataMap map = context.getJobDetail().getJobDataMap();

        int executeCount = 0;
        if (map.containsKey(NUM_EXECUTIONS)) {
            executeCount = map.getInt(NUM_EXECUTIONS);
        }

        executeCount++;

        map.put(NUM_EXECUTIONS, executeCount);

        long delay = 5000l;
        if (map.containsKey(EXECUTION_DELAY)) {
            delay = map.getLong(EXECUTION_DELAY);
        }

        try {
            Thread.sleep(delay);
        } catch (Exception ignore) {
        }

        System.err.println("  -" + context.getJobDetail().getKey()
                + " complete (" + executeCount + ").");

    }

}

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