We　propose　a　quantum　nondemolition　measurement　of　the　photon-number　distribution　for　a　weak　cavity　field　with　no　more　than　two　photons.　The　scheme　is　based　on　the　resonant　interaction　of　atoms　with　the　cavity　field,　and　thus　the　required　interaction　time　is　much　shorter　than　that　using　dispersive　interaction.　This　is　important　in　view　of　decoherence.　Our　scheme　can　also　be　used　to　generate　even　and　odd　coherent　states　for　a　weak　cavity　field　with　resonant　atoms.　©　2003　Chin.　Phys.　Soc.　and　IOP　Publishing　Ltd.