keyCode == 8 或者 keyCode == 46 对应的按键是什么？通过这个表一目了然
backspace 8 tab 9 enter 13 shift 16 ctrl 17 alt 18 pause/break 19 caps lock 20 escape 27 page up 33 Space 32 page down 34 end 35 home 36 arrow left 37 arrow up 38 arrow right 39 arrow down 40 print screen 44 insert 45 delete 46 0 48 1 49 2 50 3 51 4 52 5 53 6 54 7 55 8 56 9 57 a 65 b 66 c 67 d 68 e 69 f 70 g 71 h 72 i 73 j 74 k 75 l 76 m 77 n 78 o 79 p 80 q 81 r 82 s 83 t 84 u 85 v 86 w 87 x 88 y 89 z 90 left window key 91 right window key 92 select key 93 numpad 0 96 numpad 1 97 numpad 2 98 numpad 3 99 numpad 4 100 numpad 5 101 numpad 6 102 numpad 7 103 numpad 8 104 numpad 9 105 multiply 106 add 107 subtract 109 decimal point 110 divide 111 f1 112 f2 113 f3 114 f4 115 f5 116 f6 117 f7 118 f8 119 f9 120 f10 121 f11 122 f12 123 num lock 144 scroll lock 145 My Computer (multimedia keyboard) 182 My Calculator (multimedia keyboard) 183 semi-colon 186 equal sign 187 comma 188 dash 189 period 190 forward slash 191 open bracket 219 back slash 220 close braket 221 single quote 222