A high-statistics measurement of the neutrinos from a galactic core-collapse supernova (SN) is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos. Large liquid-scintillator detectors can be implemented to observe Galactic SN neutrinos in various reaction channels, including the inverse beta decay reaction on free protons, the elastic neutrino-proton scattering and neutrino-electron scattering, as well as the charged-current and neutral-current interactions on the carbon nuclei. In this talk, we shall illustrate that a global analysis of all these channels is very important to test the average-energy hierarchy of SN neutrinos and how the total energy is partitioned among neutrino flavors. The precision levels for the total and averaged energies of three different neutrino flavors will be also discussed. In addition, using the event time distribution of the inverse beta decay channel, the upper bound on the absolute neutrino mass is found to be $m^{}_\nu < (0.83 \pm 0.24)~{\rm eV}$ at the 95% confidence level (C.L.) for a typical galactic supernova, assuming a nearly-degenerate neutrino mass spectrum and a normal mass ordering. Finally we stress that the liquid-scintillator, water-cherenkov detector and liquid-argon detectors are complementary in the future SN neutrino observation.