使用Runnable和Handler做定时任务

1.定义Handler：

    Handler onlineHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.arg1) {
                case 0: {
                    home_0.setImageResource(R.drawable.home_2_style);
                    break;
                }
                case 1: {
                    home_0.setImageResource(R.drawable.home_2_status_style);
                    break;
                }
            }
            home_0.postInvalidate();
        }

    };

2,定义Runnable：

   Runnable onlineRunnable = new Runnable() {

        @Override
        public void run() {
            Message m = new Message();
            if (readRd() != null && readRd().trim().equals("0")) {
                m.arg1 = 0;
            } else {
                m.arg1 = 1;
            }
            onlineHandler.sendMessage(m);
//每隔5秒执行一次
            onlineHandler.postDelayed(onlineRunnable, 5000);
        }

3.启动线程：

onlineHandler.post(onlineRunnable);