<image>As shown in the figure, in the Cartesian coordinate system, the graph of the inverse function $$y= \dfrac {k}{x}(x > 0)$$ has a point $$A(m,4)$$. Draw $$AB$$ perpendicular to the $$x$$-axis at point $$B$$, then shift point $$B$$ 2 units to the right to get point $$C$$. Draw a line parallel to the $$y$$-axis through point $$C$$, which intersects the graph of the inverse function at point $$D$$.
$$(1)$$ The x-coordinate of point $$D$$ is ______ $$($$expressed as an algebraic expression containing $$m$$$$).
$$(2)$$ When $$CD= \dfrac {4}{3}$$, find the function expression of the inverse function.