Active galactic nuclei (AGNs) activity is expected to be closely related to the gas fuel availability and mechanism of the gas-inflow into the nuclear region. External processes such as galaxy interactions, major/minor mergers, and high-local-density environments affect not only physical quantities of their host galaxy (e.g., gas fuel) but also bar presence itself that is one of the possible gas-inflow mechanisms, and seem even to control the central gas supply to the galactic center. The entanglement between the three primary factors (environment, host properties, and bar presence) may have provoked conflicting observational results on the observed galaxy–AGN coevolution. In this talk, I would like to present the results of our work which relatively quantify the role of galactic environment and bar presence in blackhole feeding of spiral galaxies. The large volume-limited galaxy sample obtained from the Sloan Digital Sky Survey (SDSS) makes it possible to minimize the possible entangled effects and to isolate the effect of each of the three factors. We conclude that from the perspective of AGN–galaxy coevolution, a massive black hole is one of the key drivers of spiral galaxy evolution. If it is not met, a bar instability helps the evolution, and in the absence of bars, galaxy interactions/ mergers become important. In other words, in the presence of a massive central engine, the role of the two gas inflow mechanisms is reduced or almost disappears. We also find that bars in massive galaxies are very decisive in increasing AGN fractions when the host galaxies are inside clusters.