文章有些内容显示不全，请访问http://blog.csdn.net/simon_21/archive/2007/03/28/1544188.aspx这个地址。
 

定时执行任务的三种方法:

1）java.util.Timer.

2）ServletContextListener.

3）org.springframework.scheduling.timer.ScheduledTimerTask

1）java.util.Timer
这个方法应该是最常用的，不过这个方法需要手工启动你的任务：
        Timer timer=new Timer();
        timer.schedule(new ListByDayTimerTask(),10000,86400000);
这里的ListByDayTimerTask类必须extends TimerTask里面的run()方法。

2）ServletContextListener
这个方法在web容器环境比较方便，这样，在web server启动后就可以自动运行该任务，不需要手工操作。
将ListByDayListener implements ServletContextListener接口，在contextInitialized方法中加入启动Timer的代码，在contextDestroyed方法中加入cancel该Timer的代码；然后在web.xml中，加入listener:
<-listener>
<-listener-class>com.qq.customer.ListByDayListener</listener-class>
<-/listener>

3)org.springframework.scheduling.timer.ScheduledTimerTask如果你用spring，那么你不需要写Timer类了，在schedulingContext-timer.xml中加入下面的内容就可以了：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
<bean id="timer" class="org.springframework.scheduling.timer.TimerFactoryBean">
<property name="scheduledTimerTasks">
<list>
<ref local="MyTimeTask1"/>
</list>
</property>
</bean>

<bean id="MyTimeTask" class="com.qq.timer.ListByDayTimerTask"/>

<bean id="MyTimeTask1" class="org.springframework.scheduling.timer.ScheduledTimerTask">
<property name="timerTask">
<ref bean="MyTimeTask"/>
</property>
<property name="delay">
<value>10000</value>
</property>
<property name="period">
<value>86400000</value>
</property>
</bean>
</beans>

以上内容转载自：http://dev.csdn.net/author/xtpdcsse/ec8e8080a5b04fa79e7d4828bc807d3f.html

下面是我的实现。

1）利用java.util.Timer. 代码如下

<1>StartThread.java

package com.jview.main;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.log4j.Logger;
public class StartThread extends Thread {
    private static Logger logger = Logger.getLogger("StartThread");
    public static final int EXECUTE_CYC = 86400000; //24*60*60*1000毫秒
    int startH = 9;
    int startM = 52;
    private Timer _timer ;
    private Date _statDate;
    private Date _nowDate;
    public StartThread(){
        _nowDate = new Date();
        _timer = new Timer();
        _statDate = new Date(_nowDate.getYear(),_nowDate.getMonth(),_nowDate.getDate(),startH,startM);
    }
    public void StartUp(){
        _timer.schedule(
                new TimerTask() {
                    public void run()
                    {
                        logger.info("开始统计...");
                        try {
                            Class.forName("com.jview.stat.StatPlan").newInstance();
                        } catch (InstantiationException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } catch (IllegalAccessException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        } catch (ClassNotFoundException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                },_statDate,EXECUTE_CYC);
    }
    public static void main(String[] args) {
        StartThread _statUp = new StartThread();
        _statUp.StartUp();
    }  
}
<2>StatPlan.java
package com.jview.stat;
import java.util.Calendar;
import org.apache.log4j.Logger;
public class StatPlan {
 

    private static Logger logger = Logger.getLogger("StatPlan");
    private int i = 0;
    private StatPlanService _sps ;
    public StatPlan(){
        _sps = new StatWeekPlan();
        statPlan();
    }
    
    public void statPlan(){
        Calendar _c = Calendar.getInstance();
        logger.info("stat plan ... 执行"+ i +"次,时间："+_c.getTime());
        _sps.StatPlan();
        i++;
        for(int i = 0; i<9999;i++){
            if(i==0 || i== 9998){
                logger.info(""+i);
            }
        }
    }
}
<3>StatWeekPlan .java
import org.apache.log4j.Logger;

public class StatWeekPlan extends StatPlanService {
    private static Logger logger = Logger.getLogger("StatWeekPlan");
    public void StatPlan(){
        logger.info("this is statWeekPlan");
    }
}
<4>StatPlanService .java
public class StatPlanService {
    public void StatPlan(){   
    }
}

2）ServletContextListener.实现
<1> SysStatListener .java
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import org.apache.log4j.Logger;
public class SysStatListener implements ServletContextListener{
    private static Logger logger = Logger.getLogger("ListByDayListener");
    private StatTask _sTask;
    public void contextDestroyed(ServletContextEvent scevent) {
        String status = "停止系统统计线程";
        scevent.getServletContext().log(status);
        logger.info(status);
        _sTask.shutDown();
    }
    public void contextInitialized(ServletContextEvent scevent) {
        String status = "启动系统统计线程";
        scevent.getServletContext().log(status);
        logger.info(status);
        _sTask = new StatTask();
        _sTask.startUp();
    }
}
<2> StatTask .java
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.log4j.Logger;
public class StatTask extends Thread {
    private static Logger logger = Logger.getLogger("StartThread");
    public static final int EXECUTE_CYC = 86400000;
    int startH = 9;
    int startM = 52;
    private Timer _timer ;
    private Date _statDate;
    private Date _nowDate;
    public StatTask(){
        _nowDate = new Date();
        _timer = new Timer();
        _statDate = new Date(_nowDate.getYear(),_nowDate.getMonth(),_nowDate.getDate(),startH,startM);
    }
    public void startUp(){
        _timer.schedule(
                new TimerTask() {
                    public void run()
                    {
                        logger.info("开始统计...");
                          try {
                              Class.forName("com.jview.stat.StatPlan").newInstance();
                          } catch (InstantiationException e) {
                              // TODO Auto-generated catch block
                              e.printStackTrace();
                          } catch (IllegalAccessException e) {
                             // TODO Auto-generated catch block
                              e.printStackTrace();
                         } catch (ClassNotFoundException e) {
                            // TODO Auto-generated catch block
                             e.printStackTrace();
                         }
                    }
                },_statDate,EXECUTE_CYC);
    }
    public void shutDown(){
        _timer.cancel();
    }
<3>在web.xml中添加下面的内容（注：下面的内容放到<filter-mapping>的后面）
 <listener>
      <listener-class>com.jview.auto.stat.SysStatListener </listener-class>
  </listener>