本文实例为大家分享了JCrontab简单入门，供大家参考，具体内容如下
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。
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。