An　alternative　scheme　is　proposed　for　preparing　the　superpositions　of　coherent　states　with　controllable　weighting　factors　along　a　straight　line　for　a　cavity　field.　The　scheme　is　based　on　the　interaction　of　a　single-mode　cavity　field　with　a　resonant　two-level　atom　driven　by　a　strong　classical　field.　It　is　in　contrast　to　the　previous　methods　used　in　cavity　QED　of　injecting　a　coherent　state　into　a　cavity　via　a　microwave　source.　In　the　scheme,　the　interaction　between　the　cavity　mode　and　atoms　is　fully　resonant,　thus　the　required　interaction　time　is　greatly　shortened.　Moreover,　the　present　scheme　requires　smaller　numbers　of　operations.　In　view　of　decoherence,　a　reduction　of　interaction　time　and　numbers　of　operations　for　the　state　preparation　is　very　important　for　experimental　implementation　of　quantum　state　engineering.