JCrontab簡單入門實例詳解

本文實例為大家分享了JCrontab簡單入門，供大家參考，具體內容如下

創建一個JavaWeb項目

1、首先要下載JCrontab的相關jar包，Jcrontab-2.0-RC0.jar。放到lib文件夾下。

2、在src下新建文件jcrontab.properties如下：

#crontab.xml

文件的目錄，這個是作業調度規則
org.jcrontab.data.file =E:/EclipseWorkspace/ADemo/WebContent/WEB-INF/crontab.xml
#sax解析驅動類型
org.xml.sax.driver=org.apache.xerces.parsers.SAXParser
#datasource文件類型
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>

以上屬性自己百度一下，<seconds>0,5,10,15,20,25,30,35,40,45,50,55</seconds>這個是秒數是5的倍數就調用作業

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><!--此處路徑是絕對路徑--><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包下新建兩個java文件（文件位置見最上的截圖）【其他java文件不用理會】

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!!!"); }}

啟動tomcat後即可看到作業每隔5秒就調用一下，希望你們順利。

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。