如何在Android layout xml中通过数据绑定更改背景？

android {
    ...
    dataBinding {
        enabled = true
    }
}

<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="viewModel"
            type="com.example.ViewModel" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@{viewModel.backgroundColor}">
        ...
    </LinearLayout>
</layout>

public class ViewModel extends BaseObservable {
    private int backgroundColor;

    @Bindable
    public int getBackgroundColor() {
        return backgroundColor;
    }

    public void setBackgroundColor(int color) {
        this.backgroundColor = color;
        notifyPropertyChanged(BR.backgroundColor);
    }
}

public class MainActivity extends AppCompatActivity {
    private ViewModel viewModel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // 初始化ViewModel
        viewModel = new ViewModel();
        viewModel.setBackgroundColor(Color.RED);

        // 设置数据绑定
        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);
        binding.setViewModel(viewModel);
    }
}