import bpy

obj = bpy.data.objects['BezierCurve']

if obj.type == 'CURVE':
    for subcurve in obj.data.splines:
        curvetype = subcurve.type
        if curvetype == 'BEZIER':
            print("curve is closed:", subcurve.use_cyclic_u)
            for bezpoint in subcurve.bezier_points:
                print('knot', bezpoint.co)
                print('handle_left', bezpoint.handle_left)
                print('handle_right', bezpoint.handle_right)