java timer 定時任務

• 監聽類

package com.xx.model;

import java.util.Calendar;
import java.util.Date;
import java.util.Timer;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.xx.model.XXTask;

public class XXTimerListener  implements ServletContextListener  {
    
    private Timer timer = null;
    private static final Log log = LogFactory.getLog(XXTimerListener.class);
    final Log logrecords = LogFactory.getLog("records");

    public void contextDestroyed(ServletContextEvent arg0) {
        // TODO Auto-generated method stub
        
    }
    
    public void contextInitialized(ServletContextEvent arg0) {
        // TODO Auto-generated method stub
        
        try {
            timer = new Timer(true);
            try {
                Calendar calendar = Calendar.getInstance();
                calendar.set(Calendar.HOUR_OF_DAY, 10); // 上午10點
                calendar.set(Calendar.MINUTE, 0);
                calendar.set(Calendar.SECOND, 0);
                Date date = calendar.getTime(); // 第一次執行定時任務的時間
                                                // 如果第一次執行定時任務的時間 小于當前的時間
                                                // 此時要在 第一次執行定時任務的時間加一天，以便此任務在下個時間點執行。如果不加一天，任務會立即執行。
                if (date.before(new Date())) {
                    date = addDay(date, 1);
                }
                timer.schedule(new XXTask(),date,24*3600*1000);
                log.info("任務創建成功！");
            } catch (Exception e) {
                log.error("任務創建失敗！", e);
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    
    public Date addDay(Date date, int num) {
        Calendar startDT = Calendar.getInstance();
        startDT.setTime(date);
        startDT.add(Calendar.DAY_OF_MONTH, num);
        return startDT.getTime();
    }
}

• 任務類

package com.xx.model;
import java.util.TimerTask;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
 * @author qjl
 * 
 */
public class XXTask extends TimerTask {

    private static final Log log = LogFactory.getLog(XXTask.class);
    MeasureCountsAjax mscAjax = new MeasureCountsAjax();

    @Override
    public void run() {

        log.debug("定時任務" + new Date(System.currentTimeMillis()));
        try {
            //定時任務要執行的方法寫這里
        } catch (Exception e) {
            log.error("定時運行失敗", e);
        } finally {
        }
    }
}

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• 在web.xml中增加

　　<listener>
         <listener-class>
              com.xx.model.XXTimerListener
         </listener-class>
    </listener>

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