JCrontab简单入门实例

创建一个JavaWeb项目

 

 

1,首先要下载JCrontab的相关jar包，Jcrontab-2.0-RC0.jar。放到lib文件夹下。

 

 

2，在src下新建文件jcrontab.properties如下：

 

#crontab.xml文件的目录，这个是作业调度规则

org.jcrontab.data.file =E:/EclipseWorkspace/ADemo/WebContent/WEB-INF/crontab.xml

#sax解析驱动类型

org.xml.sax.driver=org.apache.xerces.parsers.SAXParser

#datasource文件类型

org.jcrontab.data.datasource=org.jcrontab.data.XMLSource

 

3，在WEB-INF下新建文件crontab.xml

 

<?xml version="1.0" encoding="utf-8"?>

<crontab>

<crontabentry id="2014">

<seconds>0,5,10,15,20,25,30,35,40,45,50,55</seconds>

<minutes>*</minutes>

<hours>*</hours>

<daysofmonth>*</daysofmonth>

<months>*</months>

<daysofweek>*</daysofweek>

<years>*</years>

<bussinesdays>true</bussinesdays>

<startDate></startDate>

<endDate></endDate>

<class>xu.crontab.Crontab1</class>

<method>run</method>

<parameters></parameters>

<description></description>

</crontabentry>

</crontab>

 

以上属性自己百度一下，<seconds>0,5,10,15,20,25,30,35,40,45,50,55</seconds>这个是秒数是5的倍数就调用作业

 

4，web.xml配置如下

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns="http://xmlns.jcp.org/xml/ns/javaee"

xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"

id="WebApp_ID" version="3.1">

<display-name>ADemo</display-name>

 

<servlet>

<servlet-name>LoadOnStartupServlet</servlet-name>

<servlet-class>xu.crontab.LoadCrontabServlet</servlet-class>

<init-param>

<param-name>PROPERTIES_FILE</param-name>

<!--此处路径是绝对路径 -->

<param-value>E:\EclipseWorkspace\ADemo\src\jcrontab.properties</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>LoadOnStartupServlet</servlet-name>

<url-pattern>/Startup</url-pattern>

</servlet-mapping>

</web-app>

 

5，在xu.crontab包下新建两个java文件（文件位置见最上的截图）【其他java文件不用理会】

 

LoadCrontabServlet.java

package xu.crontab;

 

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.util.Enumeration;

import java.util.Properties;

 

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

 

import org.jcrontab.Crontab;

import org.jcrontab.log.Log;

 

public class LoadCrontabServlet extends HttpServlet {

 

/**

 *

 */

private static final long serialVersionUID = 1L;

private Crontab cron = null;

 

public void init(ServletConfig config) throws ServletException {

super.init(config);

 

try {

System.out.print("Working?...");

process();

System.out.println("OK");

} catch (Exception e) {

throw new ServletException(e);

}

}

 

protected InputStream createPropertiesStream(String name) throws IOException {

return new FileInputStream(name);

}

 

public void process() {

 

String propz = "jcrontab.properties";

 

String props = getServletConfig().getInitParameter("PROPERTIES_FILE");

if (props == null) {

props = propz;

}

 

Properties propObj = new Properties();

try {

InputStream input = createPropertiesStream(props);

propObj.load(input);

} catch (IOException ioe) {

ioe.printStackTrace();

}

ServletConfig c = getServletConfig();

Enumeration keys = c.getInitParameterNames();

while (keys.hasMoreElements()) {

String key = (String) keys.nextElement();

propObj.setProperty(key, c.getInitParameter(key));

}

 

cron = Crontab.getInstance();

 

try {

ShutdownHook();

cron.init(propObj);

} catch (Exception e) {

Log.error(e.toString(), e);

}

}

 

 

public void ShutdownHook() throws Exception {

Runtime.getRuntime().addShutdownHook(new Thread() {

public void run() {

doStop();

}

});

}

 

public void destroy() {

doStop();

}

 

public void doStop() {

Log.info("Shutting down...");

cron.uninit(100);

Log.info("Stoped");

}

}

 

Crontab1.java

package xu.crontab;

 

import java.util.Date;

 

public class Crontab1 {

    public static void run(String[] args) {

       System.out.println(new Date()+"-----> hello world!!!");

    }

}

启动tomcat后即可看到作业每隔5秒就调用一下，希望你们顺利。

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