  We theoretically study the DC Josephson effect of a semiconductor nanowire
(NW) with strong spin-orbit interaction when a magnetic field is applied
parallel to the NW. We adopt a model of single scatterer in a
quasi-one-dimensional system for the case of short junctions where the size of
normal region is much smaller than the coherent length. In the case of single
conduction channel in the model, we obtain analytical expressions for the
energy levels of Andreev bound states, $E_n$, and supercurrent $I$, as a
function of phase difference $\varphi$ between two superconductors. We show the
0-$\pi$ transition by tuning the magnetic field. In the case of more than one
conduction channel, we find that $E_n (-\varphi) \ne E_n (\varphi)$ by the
interplay between the spin-orbit interaction and Zeeman effect, which results
in finite supercurrent at $\varphi =0$ (anomalous Josephson current) and
direction-dependent critical current.
