常识查找

1、放到assets文件夹里的图片路径是什么？
file:///android_asset/

2、Timer 和 CountDownTimer 如果在activity里直接new的话，在时间没走完的情况下退出activity，会导致内存泄露。但是如果把countdowntimer写到一个单例类里面，暴露出start和stop方法的话，就不会报内存泄露。

 private static final String TAG = "cj";

 static ScreenOffCountDown instance;

 public static ScreenOffCountDown getInstance() {
     if (instance == null) {
         synchronized (ScreenOffCountDown.class) {
             if (instance == null) {
                 instance = new ScreenOffCountDown();
             }
         }
     }
     return instance;
 }

 private CountDownTimer timer = new CountDownTimer(20 * 1000, 1000) {
     @Override
     public void onTick(long millisUntilFinished) {
//            Log.e(TAG, "onTick: " + millisUntilFinished);

         Log.e(TAG, "onTick: " + millisUntilFinished + "  线程名称是：" + Thread.currentThread().getName());

     }

     @Override
     public void onFinish() {
         Log.e(TAG, "onFinish: 灭屏");
         Intent intent = new Intent("haha");
         MyApplication.getInstance().sendBroadcast(intent);

     }
 };

//    public void start(){
//        timer.start();
//    }

 public void stop() {
     timer.cancel();
 }

 public void reStart() {
     timer.cancel();
     timer.start();
 }


}