public class SplashActivity extends Activity {

    private Handler handler = new Handler();

    // 保证主界面只打开一次
    private boolean isStartMain = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_splash);

        // 等待两秒后执行
        // runnable.run() 方法执行在主线程
        handler.postDelayed(new Runnable() {
            public void run() {
                startMainActivity();
            }
        }, 2000);
    }

    // 开启主界面
    private void startMainActivity() {
        if (!isStartMain) {
            isStartMain = true;
            Intent intent = new Intent(SplashActivity.this, MainActivity.class);
            startActivity(intent);

            // 关闭启动页面
            finish();
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // 点击启动页面, 快速进入到主页面
        startMainActivity();
        return super.onTouchEvent(event);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // 取消打开MainActivity的意图
        handler.removeCallbacksAndMessages(null);
    }
}

Enter   : onCreate() -> onStart() -> onResume()
>> Home : onPause() -> onStop()
Home >> : onRestart() -> onStart() onResume()
Back    : onPause() -> onStop() -> onDestroy()

Enter A : A.onCreate() -> A.onStart() -> A.onResume()
A  >> B : A.onPause() -> B.onCreate() -> B.onStart() -> B.onResume() -> A.onStop()
B  >> A : B.onPause() -> A.onRestart() -> A.onStart() -> A.onResume() -> B.onDestroy()

Enter A : A.onCreate() -> A.onStart() -> A.onResume()

// 没有 A.onStop()
A  >> B : A.onPause() -> B.onCreate() -> B.onStart() -> B.onResume()

// 没有 A.onStart() , A.onRestart()	
B  >> A : B.onPause() ->  A.onResume() -> B.onStopp() -> B.onDestroy() 

onPause() -> onStop() -> onDestroy() -> onCreate() -> onStart() -> onResume()

<!--
    播放页面横屏固定

    横竖屏切换不执行生命周期方法
    android:configChanges="keyboardHidden|screenSize|orientation"

    keyboardHidden:
        键盘隐藏

    screenSize:
        屏幕大小改变

    orientation:
        横竖屏切换不执行生命周期方法

-->
<activity
    android:name=".SystemVideoPlayer"
    android:configChanges="keyboardHidden|screenSize|orientation" />

// 1. 声明
// 定义手势识别器
private GestureDetector detector;

// 2. 创建实例并监听关心的事件
// 实例化手势识别器
detector = new GestureDetector(this, new GestureDetector.SimpleOnGestureListener() {

    // 长按
    @Override
    public void onLongPress(MotionEvent e) {
        switchPlayOrPause();
    }


    // 单击
    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        // Toast.makeText(SystemVideoPlayer.this, "点击", Toast.LENGTH_SHORT).show();
        showMediaController(!isShowMediaController);
        return true;
    }
});

// 3. 关联触摸事件
@Override
public boolean onTouchEvent(MotionEvent event) {
    // 把事件传递给手势识别器
    detector.onTouchEvent(event);
    return super.onTouchEvent(event);
}

private void touchScreenChangeVolume(MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: // 按下

            touchStartY = event.getY();
            touchRangeY = Math.min(screenHeight, screenWidth);
            touchCurrVolume = audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);

            // 移除隐藏控制面板消息
            handler.removeMessages(HIDE_CONTROLLER);
            break;

        case MotionEvent.ACTION_MOVE: // 滑动

            float moveEndY = event.getY();
            float changeDistance = (touchStartY - moveEndY);
            float changeVolume = changeDistance / touchRangeY * maxVolume;
            if (0 != changeVolume) {
                float finalVolume = Math.min(Math.max(0, changeVolume + touchCurrVolume), maxVolume);
                updateVolume((int) finalVolume);
            }

            break;

        case MotionEvent.ACTION_UP: // 离开
            // 延迟发送隐藏控制面板消息
            handler.sendEmptyMessageDelayed(HIDE_CONTROLLER, HIDE_CONTROLLER_DELAY_TIME);
            break;
    }
}