在Android中常见的几种刷新方式

在Android中常见的几种刷新方式有 Timer，Alarm和handler。
第一种：Timer
Timer这种方式最为常见，起个定时刷新的任务，不用的时候cancel掉，置为空即可。
示例代码：

Timer timer = new Timer( );
TimerTask task = new TimerTask( ) {
       public void run ( ) {
       Message message = new Message( );
       message.what = 1;
       handler.sendMessage(message);
   }
};
final Handler handler = new Handler( ) {
   public void handleMessage(Message msg) {
      switch (msg.what) {
          case 1:
               log.e("Timer","Timer");
               update( );
               break;
}

第二种：Alarm
示例代码：
开始计时
Intent intent = new Intent(widgetUpdate);
refreshIntent = PendingIntent.getBroadcast(pContext, 0, intent, 0);
alarm = (AlarmManager)pContext.getSystemService(Context.ALARM_SERVICE);
alarm.setRepeating(AlarmManager.RTC, 0, 1000, refreshIntent);//每秒刷新1次
停止计时
if (alarm!=null) {
     alarm.cancel(refreshIntent);
     refreshIntent.cancel();
     refreshIntent = null;
  alarm = null;
}

第三种：handler
private Handler handler = new Handler();
    private Runnable runnable = new Runnable() {
         public void run () {
             update();
         handler.postDelayed(this,1000);
      }
    };

开始计时
handler.removeCallbacks(runnable);
handler.postDelayed(runnable,1000);
停止计时
handler.removeCallbacks(runnable);