Java Web项目中编写定时任务的实现

<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:task="http://www.springframework.org/schema/task" 
  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd 
  http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd"> 
 
 <task:scheduler id="scheduler" pool-size="200"/> 
 <task:scheduled-tasks> 
  <!-- 你的task --> 
  <task:scheduled ref="xxxTask" method="execute" cron="0 0 * * * ?"/> 
 </task:scheduled-tasks> 
 <task:annotation-driven scheduler="scheduler"/> 
</beans> 

@Component 
public class XxxListener implements ApplicationContextAware { 
 
 // 防止加载多次 
 private static final AtomicInteger INIT_LOCK = new AtomicInteger(0); 
 
 @Override 
 public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { 
 
  if (INIT_LOCK.incrementAndGet() > 1) { 
   // 类已加载过 
   return; 
  } 
 
  Resource resource = applicationContext.getResource("classpath:<标识文件>"); 
  if (!resource.exists()) { 
   // 文件不存在，不启动 
   return; 
  } 
   
  ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(applicationContext); 
  context.setConfigLocations("classpath:spring/job.xml"); 
  context.refresh(); 
 } 
}