  In a recent work, we present a new point of view to the relation of gravity
and thermodynamics, in which we derive the \sch~solution through thermodynamic
laws by the aid of the Misner-Sharp mass in an adiabatic system. In this paper
we continue to investigate the relation between gravity and thermodynamics for
obtaining solutions via thermodynamics. We generalize our studies on
gravi-thermodynamics in Einstein gravity to modified gravity theories. By using
the first law with the assumption that the Misner-Sharp mass is the mass for an
adiabatic system, we reproduce the Boulware-Deser-Cai solution in Guass-Bonnet
gravity. Using this gravi-thermodynamics thought, we obtain a NEW class of
solution in $F(R)$ gravity in an $n$-dimensional (n$\geq$3) spacetime which
permits three-type $(n-2)$-dimensional maximally symmetric subspace, as an
extension of our recent three-dimensional black hole solution, and
four-dimensional Clifton-Barrow solution in $F(R)$ gravity.
