Android 计时器及TimerTask is scheduled already的Bug处理

public class HXTimer  {

    private int recLen=15; //倒计时时长
    private TimerTask timerTask=null;//定时任务
    private  Handler mHandler=null;
    private Timer timer=null;//计时器
    
   public   HXTimer(int recLen, long delay, long period, Handler mHandler){
       this.recLen=recLen;
       this.mHandler=mHandler;;
       timer=new Timer();
       getTimerTastInstance();
       timer.schedule(timerTask,delay,period);
   }
    //获取一个定时任务实例
    private void   getTimerTastInstance(){
        timerTask=new TimerTask() {
            @Override
            public void run() {
                recLen--;
                if(recLen <= 1){
                    timer.cancel();
                }
                if(mHandler!=null) {
                    Message message = new Message();
                    Bundle bundle = new Bundle();
                    bundle.putInt("recLen", recLen);
                    message.setData(bundle);
                    message.what = 2000;
                    mHandler.sendMessage(message);
                }
            }
        };
    }
    public void cancel(){
        if(timerTask!=null) {
            timerTask.cancel();
            timerTask = null;
        }
        if(timer!=null) {
            timer=null;
        }

    }
}