Only fullscreen activities can request orientation 解决方法

google出于安全的考虑，对android8.0以后的版本做的处理，当一个Activity固定方向并且是透明的，在8.0以后的版本中就会抛出异常：

     java.lang.IllegalStateException: Only fullscreen opaque activities can request orientation

异常抛出条件如下：

    ActivityInfo.isFixedOrientation(requestedOrientation) —— 表示判断当前的|Activity是否固定了方向

    fullscreen —— 表示Activity是否是透明的或者是否悬浮在Activity上，是透明的或者悬浮在Activity上fullscreen就等于false

    appInfo.targetSdkVersion >= O —— 表示版本号大于等于26

解决方法

1. 利用反射，修改mActivityInfo中的变量screenOrientation,设置成SCREEN_ORIENTATION_UNSPECIFIED
2. override setRequestedOrientation方法，直接return

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        if (Build.VERSION.SDK_INT == Build.VERSION_CODES.O && isTranslucentOrFloating()) {
            boolean result = fixOrientation();
            XLog.i(XLog.BASE, "onCreate fixOrientation when Oreo, result = " + result);
        }
        super.onCreate(savedInstanceState);
    }
 

    @Override
    public void setRequestedOrientation(int requestedOrientation) {
        if (Build.VERSION.SDK_INT == Build.VERSION_CODES.O && isTranslucentOrFloating()) {
            XLog.i(XLog.BASE, "avoid calling setRequestedOrientation when Oreo.");
            return;
        }
        super.setRequestedOrientation(requestedOrientation);
    }


    private boolean isTranslucentOrFloating(){
        boolean isTranslucentOrFloating = false;
        try {
            int [] styleableRes = (int[]) Class.forName("com.android.internal.R$styleable").getField("Window").get(null);
            final TypedArray ta = 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;
    }

    private boolean fixOrientation(){
        try {
            Field field = Activity.class.getDeclaredField("mActivityInfo");
            field.setAccessible(true);
            ActivityInfo o = (ActivityInfo)field.get(this);
            o.screenOrientation = -1;
            field.setAccessible(false);
            return true;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }