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：

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

#============================================================================
# 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:

<?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-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

<?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: