Android 4.x上适配设置DialogFragment背景透明--可拓展实现悬浮关闭按钮

方法一：设置style -- 无效

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        LayoutInflater inflater = getActivity().getLayoutInflater();
        View view = inflater.inflate(R.layout.dialog_confirm_layout, null);

        TextView descTextView = (TextView) view.findViewById(R.id.dialog_content_tv);
        descTextView.setText("Android 4.2 DialogFragment");

        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(), R.style.CustomDialog);
        builder.setView(view);
        return builder.create();
    }

方法二：在onStart中设置 -- 无效

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        LayoutInflater inflater = getActivity().getLayoutInflater();
        View view = inflater.inflate(R.layout.dialog_confirm_layout, null);

        TextView descTextView = (TextView) view.findViewById(R.id.dialog_content_tv);
        descTextView.setText("Android 4.2 DialogFragment");

        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
        builder.setView(view);
        return builder.create();
    }

    @Override
    public void onStart() {
        super.onStart();

        Window window = getDialog().getWindow();
        WindowManager.LayoutParams windowParams = window.getAttributes();
        windowParams.dimAmount = 0.0f;
        window.setAttributes(windowParams);
    }

终极办法：使用V7兼容包 -- 生效