Android 監聽鍵盤彈出/隱藏

在部分安卓機型遇到 SoftInputMode 設置 adjustPan / adjustResize 無效的情況。於是對鍵盤做了單獨的監聽，方便統一處理

private int oldDiff = 0;

@Override
protected void onCreate(...) {
    listenKeyboardVisible();
}

private void listenKeyboardVisible() {
    final View activityRoot = getWindow().getDecorView();
    if (activityRoot ==null) {
        return;
    }
    mainContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        private final Rect r =new Rect();
        @Override
        public void onGlobalLayout() {
            activityRoot.getWindowVisibleDisplayFrame(r);
            int diff = activityRoot.getRootView().getHeight() -r.height();
            //鍵盤是否彈出
            boolean isOpen = (diff > 200);
            if(diff!=oldDiff){
                Log.d("keyboard", "keyboard open: "+isOpen);
                oldDiff = diff;

                // do someting...
                
            }
        }
    });
}