private void setListenerToRootView() {
        final View rootView = getWindow().getDecorView().findViewById(android.R.id.content);
        rootView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                boolean mKeyboardUp = isKeyboardShown(rootView);
                if (mKeyboardUp) {
                    Toast.makeText(EdittextActivity.this, "键盘弹出", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(EdittextActivity.this, "键盘收起", Toast.LENGTH_SHORT).show();
                }
                //如果只想检测一次，需要注销
                //rootView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
            }
        });
    }

    private boolean isKeyboardShown(View rootView) {
        final int softKeyboardHeight = 100;
        Rect r = new Rect();
        rootView.getWindowVisibleDisplayFrame(r);
        DisplayMetrics dm = rootView.getResources().getDisplayMetrics();
        int heightDiff = rootView.getBottom() - r.bottom;
        return heightDiff > softKeyboardHeight * dm.density;
    }