/**
   * 全屏显示
   */
  private void setFullSreen() {
    WindowManager.LayoutParams params = getWindow().getAttributes();
    params.flags |= WindowManager.LayoutParams.FLAG_FULLSCREEN;
    getWindow().setAttributes(params);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
    //getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_FULLSCREEN); // Activity全屏显示，且状态栏被覆盖掉
  }

 /**
   * 退出全屏
   */
  private void exitFullSreen() {
    WindowManager.LayoutParams params = getWindow().getAttributes();
    params.flags &= (~WindowManager.LayoutParams.FLAG_FULLSCREEN);
    getWindow().setAttributes(params);
    getWindow().clearFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);
    //getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN); // Activity全屏显示，但是状态栏不会被覆盖掉，而是正常显示，只是Activity顶端布局会被覆盖住
  }