1：handler实现定时器的功能

Handler handler=new Handler();

//立即执行Runnable对象
   public final boolean post(Runnable r);
   //在指定时间uptimeMillis 后执行Runnable对象
   public final boolean postAtTime(Runnable r,long uptimeMillis);
    //在指定的时间间隔delayMillis 执行Runnable对象
   public final boolean postDelayed(Runnable r,long delayMillis);

在指定时间
     handler.postAtTime(new Runnable() {
      public void run() {
       // TODO Auto-generated method stub
       ToastUtils.show(mContext, "数据已备份");
      }
      }, android.os.SystemClock.uptimeMillis()+2000);

时间间隔

handler.postDelayed(this, 2000);

public void run() {
    // TODO Auto-generated method stub
   Log.e("+++++++++>",  "数据已备份");
    handler.postDelayed(this,2000); 
   }