Only fullscreen activities can r

这是个只有8.0才会出现的错误(╯‵□′)╯︵┻━┻

Entry ent = AttributeCache.instance().get(packageName,realTheme, com.android.internal.R.styleable.Window, userId);
final boolean translucent = ent != null && (ent.array.getBoolean(com.android.internal.R.styleable.Window_windowIsTranslucent, false)|| (!ent.array.hasValue(
                com.android.internal.R.styleable.Window_windowIsTranslucent) &&  ent.array.getBoolean(com.android.internal.R.styleable.Window_windowSwipeToDismiss,false)));
fullscreen = ent != null && !ent.array.getBoolean(com.android.internal.R.styleable.Window_windowIsFloating, false) && !translucent;
fullscreen = ent != null && !ActivityInfo.isTranslucentOrFloating(ent.array);
noDisplay = ent != null && ent.array.getBoolean(com.android.internal.R.styleable.Window_windowNoDisplay, false);

if (ActivityInfo.isFixedOrientation(requestedOrientation) && !fullscreen && appInfo.targetSdkVersion > O) {
    throw new IllegalStateException("Only fullscreen activities can request orientation");
}

简单说就是背景透明的Activity设置固定方向就崩了。。。
分两种情况
1.Activity的风格为透明，在manifest文件中指定了一个方向，则在onCreate中crash
2.Activity的风格为透明，如果调用setRequestedOrientation方法固定方向，则crash

解决

AndroidManifest.xml的activity去掉:android:screenOrientation=”portrait”
在onCreate中用代码设置

       if (Build.VERSION.SDK_INT == Build.VERSION_CODES.O && ScreenOrientationUtil.getInstance().isTranslucentOrFloating(this)) {
          //安卓8.0，透明，不能设置固定方向
       } else {
           setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
       }

    //判断是透明的方法
    public boolean isTranslucentOrFloating(Activity activity){
        boolean isTranslucentOrFloating = false;
        try {
            int [] styleableRes = (int[]) Class.forName("com.android.internal.R$styleable").getField("Window").get(null);
            final TypedArray ta = activity.obtainStyledAttributes(styleableRes);
            Method m = ActivityInfo.class.getMethod("isTranslucentOrFloating", TypedArray.class);
            m.setAccessible(true);
            isTranslucentOrFloating = (boolean)m.invoke(null, ta);
            m.setAccessible(false);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return isTranslucentOrFloating;
    }

当然，也可以简单粗暴一点，不用判断版本以及是否透明了

        try {
            setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        } catch (Exception ignored) {
        }