  The energy equalities of compressible Navier-Stokes equations with general
pressure law and degenerate viscosities are studied. By using a unified
approach, we give sufficient conditions on the regularity of weak solutions for
these equalities to hold. The method of proof is suitable for the case of
periodic as well as homogeneous Dirichlet boundary conditions. In particular,
by a careful analysis using the homogeneous Dirichlet boundary condition, no
boundary layer assumptions are required when dealing with bounded domains with
boundary.
