如何在Android的画布线条下绘制自定义阴影

public class CustomView extends View {
    private Paint paint;

    public CustomView(Context context) {
        super(context);
        init();
    }

    public CustomView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setStrokeWidth(5);
        paint.setColor(Color.BLACK);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        // 绘制线条
        canvas.drawLine(100, 100, 500, 100, paint);

        // 设置阴影效果
        paint.setShadowLayer(10, 0, 0, Color.GRAY);

        // 绘制带阴影的线条
        canvas.drawLine(100, 200, 500, 200, paint);
    }
}