  Conductance of metallic heterostructures can be controlled by applying a gate
voltage to a region in the transport channel. For sufficiently long phase
coherent channels, oscillations appear in conductance versus chemical potential
plot, which can be explained by Fabry-P\'erot interference. In this work, we
study DC Josephson effect in a superconductor-normal metal-superconductor
junctions. The chemical potential of the normal metal (NM) region can be tuned
by an applied gate voltage. We numerically obtain the Andreev bound states
formed within the superconducting gap and calculate Josephson current by
summing up the currents carried by the occupied Andreev bound states. We find
that the Josephson current oscillates as a function of the chemical potential
in the NM region, and these oscillations can be explained by Fabry-P\'erot
interference condition. We find that Josephson current carried by one bound
state can be higher than that carried by two or more bound states.
