在项目中使用到定时任务,除了使用Spring自带的调度之外,还可以使用Servlet上下文实现
一、创建一个Listener 类,实现ServletContextListener 接口,实现接口中的方法:
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
/**
* 侦听器类 和Timer 结合起来定时执行任务
*/
public class ContextListener implements ServletContextListener {
private java.util.Timer timer = null;
public void contextInitialized(ServletContextEvent arg0) {
timer = new java.util.Timer(true);// 创建一个新计时器,指定其相关的线程作为守护程序运行。
//System.out.println("启动定时器");
//调度器,EarlyWarningTask() 为自定义调度任务
//初始化时就执行一次任务
timer.schedule(new EarlyWarningTask(),10, 60*60*1000);//执行任务前延迟10毫秒,执行任务的间隔60*60*1000毫秒
//System.out.println("调度任务添加完成");
}
public void contextDestroyed(ServletContextEvent arg0) {
timer.cancel();
//System.out.println("定时任务销毁");
}
}
二、获得Spring 的ApplicationContext配置信息,以便在调度任务中读取配置文件中的相关业务方法
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AppContext {
private static AppContext instance;
private AbstractApplicationContext appContext;
public synchronized static AppContext getInstance() {
if (instance == null) {
instance = new AppContext();
}
return instance;
}
private AppContext() {
this.appContext = new ClassPathXmlApplicationContext(
"/applicationContext.xml");
}
public AbstractApplicationContext getAppContext() {
return appContext;
}
}
三、自定义调度任务类,继承TimerTask 类
import java.util.TimerTask;
public class EarlyWarningTask extends TimerTask {
private static final int C_SCHEDULE_HOUR = 23;//执行时间23时
private static boolean isRunning = false;
//通过AppContext 类,获得配置文件中相关业务方法
//inStorageDetailImp
protected IInStorageDetailService getInStorageDetailService(){
return (IInStorageDetailService)AppContext.getInstance().getAppContext()
.getBean("inStorageDetailImp");
}
// goodsWarningImp
protected IGoodsWarningService getGoodsWarningService(){
return (IGoodsWarningService)AppContext.getInstance().getAppContext()
.getBean("goodsWarningImp");
}
// lendOutAccountImp
protected ILendOutAccountService getLendOutAccountService(){
return (ILendOutAccountService) AppContext.getInstance().getAppContext()
.getBean("lendOutAccountImp");
}
//lendOutWarningImp
protected ILendOutWarningService getLendOutWarningService(){
return (ILendOutWarningService)AppContext.getInstance().getAppContext()
.getBean("lendOutWarningImp");
}
//任务在run()方法中实现
@Override
public void run() {
Calendar cal = Calendar.getInstance() ;
if(!isRunning){
if(C_SCHEDULE_HOUR==cal.get(Calendar.HOUR_OF_DAY)){//HOUR_OF_DAY 用于 24 小时制时钟
isRunning = true;
System.out.println("执行定时任务");
//任务代码
//…………………………
isRunning = false;
System.out.println("定时任务结束");
}else {
System.out.println("未到定时任务时间");
}
}else{
System.out.println("上一个定时任务未结束");
}
}
四、web.xml配置监听
<listener>
<listener-class>com.cl.gdb.util.ContextListener</listener-class>
</listener>
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