  The stationnary Josephson effect in a clean
Superconductor-Ferromagnet-Superconductor junction is revisited for arbitrarily
large spin polarizations. The quasiclassical calculation of the supercurrent
assumes that the Andreev reflection is complete for all channels. However, De
Jong and Beenakker have shown that the Andreev reflection at a clean FS
interface is incomplete, due to the exchange interaction in the ferromagnet.
Taking into account this incomplete Andreev reflection, we investigate the
quasiparticle spectrum, the Josephson current and the $0-\pi$ transition in a
ballistic single channel SFS junction. We find that energy gaps open in the
phase dependent spectrum. Although the spectrum is strongly modified when the
exchange energy increases, the Josephson current and the $0-\pi$ transition are
only weakly affected by the incomplete Andreev reflection, except when the
exchange energy is close to the Fermi energy.
