JCrontab简单入门实例详解

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。