We present a model of cosmic ray (CR) injection into the Galactic space based on recent -ray observations of supernova remnants (SNRs) and pulsar wind nebulae (PWNe) by the Fermi Large Area Telescope (Fermi ) and atmospheric Cherenkov telescopes (ACTs). Steady-state (SS) injection of nuclear particles and electrons ( − ) from the Galactic ensemble of SNRs, and electrons and positrons ( + ) from the Galactic ensemble of PWNe are assumed, with their spectra deduced from -ray observations and recent evolution models. The ensembles of SNRs and PWNe are assumed to share the same spatial distributions and the secondary CR production in dense molecular clouds interacting with SNRs is incorporated in the model. Propagation of CRs to Earth is calculated using GALPROP with 2 source distributions and 2 Galaxy halo sizes. We show that this observation-based model reproduces the positron fraction + /( − + + ) and antiproton-to-proton ratio (¯/ ) reported by PAMELA reasonably well without calling for new sources. Significant discrepancy is found, however, between our model and the − + + spectrum measured by Fermi below ∼ 20 GeV. Important quantities for Galactic CRs, including their energy injection, average lifetime, and mean gas density along their typical propagation path are also presented.