Quartz 框架快速入门（三）

   在前面两篇文章中简单介绍了在java应用程序中如何使用Quartz框架，这一篇中我们将看到如何在web环境下通过配置文件来完成Quartz的后台作业调度，而不必手工去创建Trigger和Scheduler，其步骤如下：

首先创建一个Web项目，将quartz-1.6.0.jar,以及lib目录下面core下所有jar，optional目录下的所有commons-beanutils.jar和commons-digester-1.7.jar，build目录下的jta.jar都放入Web项目的WEB-INF"lib目录下。

创建一个简单的job类HelloWorld，它的功能很简单，就是输出当前的时间，代码如下：

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> package com.vista.quartz;

import java.util.Date;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;

public class Helloworld implements Job
{
private static Log logger = LogFactory.getLog(Helloworld. class ); // 日志记录器
public Helloworld()
{
}
public void execute(JobExecutionContext context) throws JobExecutionException
{
logger.info( " Hello World! - " + new Date());
}
}

然后按照上一篇文章《Quartz 框架快速入门（二）》中所讲述的内容编写quartz.properties文件。如果启动项目的时候，Quartz没有在工程中找到该文件，就会从自己的jar包下面读取其默认的properties文件，其内容如下

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> #============================================================================
# Configure Main Scheduler Properties
#============================================================================
org.quartz.scheduler.instanceName = QuartzScheduler
org.quartz.scheduler.instanceId = AUTO
#============================================================================
# Configure ThreadPool
#============================================================================
org.quartz.threadPool.class = org.quartz.simpl.SimpleThreadPool
org.quartz.threadPool.threadCount = 5
org.quartz.threadPool.threadPriority = 5
#============================================================================
# Configure JobStore
#============================================================================
org.quartz.jobStore.misfireThreshold = 60000
org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore
#============================================================================
# Configure Plugins
#============================================================================
org.quartz.plugin.triggHistory.class = org.quartz.plugins.history.LoggingJobHistoryPlugin
org.quartz.plugin.jobInitializer.class = org.quartz.plugins.xml.JobInitializationPlugin
org.quartz.plugin.jobInitializer.fileNames = jobs.xml
org.quartz.plugin.jobInitializer.overWriteExistingJobs = true
org.quartz.plugin.jobInitializer.failOnFileNotFound = true
org.quartz.plugin.jobInitializer.scanInterval = 10
org.quartz.plugin.jobInitializer.wrapInUserTransaction = false

然后编写任务配置文件jobs.xml，内容如下:

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> <? xml version='1.0' encoding='utf-8' ?>
< quartz xmlns ="http://www.opensymphony.com/quartz/JobSchedulingData"
xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation ="http://www.opensymphony.com/quartz/JobSchedulingData
http://www.opensymphony.com/quartz/xml/job_scheduling_data_1_5.xsd"
version ="1.5" >
< job >
< job-detail >
< name > HelloWorld </ name >
< group > DEFAULT </ group >
< description >
A job that just for test
</ description >
< job-class >
com.vista.quartz.Helloworld
</ job-class >
< volatility > false </ volatility >
< durability > false </ durability >
< recover > false </ recover >
</ job-detail >
< trigger >
< simple >
< name > HelloTrigger1 </ name >
< group > DEFAULT </ group >
< job-name > HelloWorld </ job-name >
< job-group > DEFAULT </ job-group >
< start-time > 2008-09-03T15:56:30 </ start-time >
<!-- repeat indefinitely every 10 seconds -->
< repeat-count > -1 </ repeat-count >
< repeat-interval > 10000 </ repeat-interval >
</ simple >
</ trigger >
</ job >
</ quartz >

可以看到，在配置文件中把jobdetail和trigger都作了完整的定义，并组合成一个job。下面，我们把上面两个文件都放入/WEB-INF/classes目录下，然后按照api中的说明修改一下web.xml，内容如下

<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> <? xml version="1.0" encoding="UTF-8" ?>
< web-app version ="2.4"
xmlns ="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation ="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" >
< servlet >
< servlet-name > QuartzInitializer </ servlet-name >
< display-name > Quartz Initializer Servlet </ display-name >
< servlet-class >
org.quartz.ee.servlet.QuartzInitializerServlet
</ servlet-class >
< load-on-startup > 1 </ load-on-startup >
< init-param >
< param-name > config-file </ param-name >
< param-value > /quartz.properties </ param-value >
</ init-param >
< init-param >
< param-name > shutdown-on-unload </ param-name >
< param-value > true </ param-value >
</ init-param >
</ servlet >
< welcome-file-list >
< welcome-file > index.jsp </ welcome-file >
</ welcome-file-list >
</ web-app >

这样，在启动Tomcat的时候，QuartzInitializerServlet这个Servlet就会自动读取quartz.properties这个配置文件，并初始化调度信息，启动Scheduler。

启动tomcat后，就可以看到输出的结果: