Android : 输入设备键值从底层到应用层的映射流程
Android : 输入设备键值从底层到应用层的映射流程
一、Android输入子系统简介：
Android输入事件的源头是位于/dev/input/下的设备节点，而输入系统的终点是由WMS管理的某个窗口。最初的输入事件为内核生成的原始事件，而最终交付给窗口的则是KeyEvent或MotionEvent对象。因此Android输入系统的主要工作是读取设备节点中的原始事件，将其加工封装，然后派发给一个特定的窗口以及窗口中的控件。这个过程由InputManagerService（以下简称IMS）系统服务为核心的多个参与者共同完成。
图1：输入系统的总体流程与参与者
二、键值映射关系：
①IR硬件扫描码在驱动里面被映射为 include/uapi/linux/input.h 里面定义的某个键值，但这个键值只在linux系统(内核)中使用。
②Android通过源码目录下的 device/xxx/xxx.kl(keylayout) 文件完成linux键值到Android系统要使用的键值映射。
以HID设备为例，首先内核中的键值转换在drivers/hid/hid-input.c 中进行映射，键值通道也有多种类型，例如：keyboard、consumer 等等；
//keyboard通道键值则是在如下数组添加修改：
static const unsigned char hid_keyboard[256] = {
0, 0, 0, 0, 30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38,
50, 49, 24, 25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44, 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 28, 1, 14, 15, 57, 12, 13, 26,
27, 43, 43, 39, 40, 41, 51, 52, 53, 58, 59, 60, 61, 62, 63, 64,
65, 66, 67, 68, 87, 88, 99, 70,119,110,102,104,111,107,109,106,
105,108,103, 69, 98, 55, 74, 78, 96, 79, 80, 81, 75, 76, 77, 71,
72, 73, 82, 83, 86,127,116,117,183,184,185,186,187,188,189,190,
191,192,193,194,134,138,130,132,128,129,131,137,133,135,136,113,
115,114,unk,unk,unk,121,unk, 89, 93,124, 92, 94, 95,unk,unk,unk,
122,123, 90, 91, 85,unk,unk,unk,unk,unk,unk,unk,111,unk,unk,unk,
unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,
unk,unk,unk,unk,unk,unk,179,180,unk,unk,unk,unk,unk,unk,unk,unk,
unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,unk,
unk,unk,unk,unk,unk,unk,unk,unk,111,unk,unk,unk,unk,unk,unk,unk,
29, 42, 56,125, 97, 54,100,126,164,166,165,163,161,115,114,113,
150,158,159,128,136,177,178,176,142,152,173,140,unk,unk,unk,unk
};
......
//然后在以下代码部分使用：
case HID_UP_KEYBOARD:
set_bit(EV_REP, input->evbit);
if ((usage->hid & HID_USAGE) < 256) {
if (!hid_keyboard[usage->hid & HID_USAGE]) goto ignore;
map_key_clear(hid_keyboard[usage->hid & HID_USAGE]);
} else
map_key(KEY_UNKNOWN);
break;
//consumer通道键值则是在如下添加修改：
case HID_UP_CONSUMER: /* USB HUT v1.12, pages 75-84 */
switch (usage->hid & HID_USAGE) {
case 0x000: goto ignore;
case 0x030: map_key_clear(KEY_POWER); break;
case 0x031: map_key_clear(KEY_RESTART); break;
case 0x032: map_key_clear(KEY_SLEEP); break;
case 0x034: map_key_clear(KEY_SLEEP); break;
case 0x035: map_key_clear(KEY_KBDILLUMTOGGLE); break;
case 0x036: map_key_clear(BTN_MISC); break;
case 0x040: map_key_clear(KEY_MENU); break; /* Menu */
case 0x041: map_key_clear(KEY_SELECT); break; /* Menu Pick */
case 0x042: map_key_clear(KEY_UP); break; /* Menu Up */
case 0x043: map_key_clear(KEY_DOWN); break; /* Menu Down */
case 0x044: map_key_clear(KEY_LEFT); break; /* Menu Left */
case 0x045: map_key_clear(KEY_RIGHT); break; /* Menu Right */
case 0x046: map_key_clear(KEY_ESC); break; /* Menu Escape */
case 0x047: map_key_clear(KEY_KPPLUS); break; /* Menu Value Increase */
case 0x048: map_key_clear(KEY_KPMINUS); break; /* Menu Value Decrease */
case 0x060: map_key_clear(KEY_INFO); break; /* Data On Screen */
case 0x061: map_key_clear(KEY_SUBTITLE); break; /* Closed Caption */
case 0x063: map_key_clear(KEY_VCR); break; /* VCR/TV */
case 0x065: map_key_clear(KEY_CAMERA); break; /* Snapshot */
case 0x069: map_key_clear(KEY_RED); break;
case 0x06a: map_key_clear(KEY_GREEN); break;
case 0x06b: map_key_clear(KEY_BLUE); break;
case 0x06c: map_key_clear(KEY_YELLOW); break;
case 0x06d: map_key_clear(KEY_ZOOM); break;
case 0x082: map_key_clear(KEY_VIDEO_NEXT); break;
case 0x083: map_key_clear(KEY_LAST); break;
case 0x084: map_key_clear(KEY_ENTER); break;
case 0x088: map_key_clear(KEY_PC); break;
case 0x089: map_key_clear(KEY_TV); break;
case 0x08a: map_key_clear(KEY_WWW); break;
case 0x08b: map_key_clear(KEY_DVD); break;
case 0x08c: map_key_clear(KEY_PHONE); break;
case 0x08d: map_key_clear(KEY_PROGRAM); break;
case 0x08e: map_key_clear(KEY_VIDEOPHONE); break;
case 0x08f: map_key_clear(KEY_GAMES); break;
case 0x090: map_key_clear(KEY_MEMO); break;
case 0x091: map_key_clear(KEY_CD); break;
case 0x092: map_key_clear(KEY_VCR); break;
case 0x093: map_key_clear(KEY_TUNER); break;
case 0x094: map_key_clear(KEY_EXIT); break;
case 0x095: map_key_clear(KEY_HELP); break;
case 0x096: map_key_clear(KEY_TAPE); break;
case 0x097: map_key_clear(KEY_TV2); break;
case 0x098: map_key_clear(KEY_SAT); break;
case 0x09a: map_key_clear(KEY_PVR); break;
case 0x09c: map_key_clear(KEY_CHANNELUP); break;
case 0x09d: map_key_clear(KEY_CHANNELDOWN); break;
case 0x0a0: map_key_clear(KEY_VCR2); break;
case 0x0b0: map_key_clear(KEY_PLAY); break;
case 0x0b1: map_key_clear(KEY_PAUSE); break;
case 0x0b2: map_key_clear(KEY_RECORD); break;
case 0x0b3: map_key_clear(KEY_FASTFORWARD); break;
case 0x0b4: map_key_clear(KEY_REWIND); break;
case 0x0b5: map_key_clear(KEY_NEXTSONG); break;
case 0x0b6: map_key_clear(KEY_PREVIOUSSONG); break;
case 0x0b7: map_key_clear(KEY_STOPCD); break;
case 0x0b8: map_key_clear(KEY_EJECTCD); break;
case 0x0bc: map_key_clear(KEY_MEDIA_REPEAT); break;
case 0x0b9: map_key_clear(KEY_SHUFFLE); break;
case 0x0bf: map_key_clear(KEY_SLOW); break;
case 0x0cd: map_key_clear(KEY_PLAYPAUSE); break;
case 0x0e0: map_abs_clear(ABS_VOLUME); break;
case 0x0e2: map_key_clear(KEY_MUTE); break;
case 0x0e5: map_key_clear(KEY_BASSBOOST); break;
case 0x0e9: map_key_clear(KEY_VOLUMEUP); break;
case 0x0ea: map_key_clear(KEY_VOLUMEDOWN); break;
case 0x0f5: map_key_clear(KEY_SLOW); break;
case 0x182: map_key_clear(KEY_BOOKMARKS); break;
case 0x183: map_key_clear(KEY_CONFIG); break;
case 0x184: map_key_clear(KEY_WORDPROCESSOR); break;
case 0x185: map_key_clear(KEY_EDITOR); break;
case 0x186: map_key_clear(KEY_SPREADSHEET); break;
case 0x187: map_key_clear(KEY_GRAPHICSEDITOR); break;
case 0x188: map_key_clear(KEY_PRESENTATION); break;
case 0x189: map_key_clear(KEY_DATABASE); break;
case 0x18a: map_key_clear(KEY_MAIL); break;
case 0x18b: map_key_clear(KEY_NEWS); break;
case 0x18c: map_key_clear(KEY_VOICEMAIL); break;
case 0x18d: map_key_clear(KEY_ADDRESSBOOK); break;
case 0x18e: map_key_clear(KEY_CALENDAR); break;
case 0x191: map_key_clear(KEY_FINANCE); break;
case 0x192: map_key_clear(KEY_CALC); break;
case 0x193: map_key_clear(KEY_PLAYER); break;
case 0x194: map_key_clear(KEY_FILE); break;
case 0x196: map_key_clear(KEY_WWW); break;
case 0x199: map_key_clear(KEY_CHAT); break;
case 0x19c: map_key_clear(KEY_LOGOFF); break;
case 0x19e: map_key_clear(KEY_COFFEE); break;
case 0x1a6: map_key_clear(KEY_HELP); break;
case 0x1a7: map_key_clear(KEY_DOCUMENTS); break;
case 0x1ab: map_key_clear(KEY_SPELLCHECK); break;
case 0x1ae: map_key_clear(KEY_KEYBOARD); break;
case 0x1b6: map_key_clear(KEY_IMAGES); break;
case 0x1b7: map_key_clear(KEY_AUDIO); break;
case 0x1b8: map_key_clear(KEY_VIDEO); break;
case 0x1bc: map_key_clear(KEY_MESSENGER); break;
case 0x1bd: map_key_clear(KEY_INFO); break;
case 0x201: map_key_clear(KEY_NEW); break;
case 0x202: map_key_clear(KEY_OPEN); break;
case 0x203: map_key_clear(KEY_CLOSE); break;
case 0x204: map_key_clear(KEY_EXIT); break;
case 0x207: map_key_clear(KEY_SAVE); break;
case 0x208: map_key_clear(KEY_PRINT); break;
case 0x209: map_key_clear(KEY_PROPS); break;
case 0x21a: map_key_clear(KEY_UNDO); break;
case 0x21b: map_key_clear(KEY_COPY); break;
case 0x21c: map_key_clear(KEY_CUT); break;
case 0x21d: map_key_clear(KEY_PASTE); break;
case 0x21f: map_key_clear(KEY_FIND); break;
case 0x221: map_key_clear(KEY_SEARCH); break;
case 0x222: map_key_clear(KEY_GOTO); break;
case 0x223: map_key_clear(KEY_HOMEPAGE); break;
case 0x224: map_key_clear(KEY_BACK); break;
case 0x225: map_key_clear(KEY_FORWARD); break;
case 0x226: map_key_clear(KEY_STOP); break;
case 0x227: map_key_clear(KEY_REFRESH); break;
case 0x22a: map_key_clear(KEY_BOOKMARKS); break;
case 0x22d: map_key_clear(KEY_ZOOMIN); break;
case 0x22e: map_key_clear(KEY_ZOOMOUT); break;
case 0x22f: map_key_clear(KEY_ZOOMRESET); break;
case 0x233: map_key_clear(KEY_SCROLLUP); break;
case 0x234: map_key_clear(KEY_SCROLLDOWN); break;
case 0x238: map_rel(REL_HWHEEL); break;
case 0x23d: map_key_clear(KEY_EDIT); break;
case 0x25f: map_key_clear(KEY_CANCEL); break;
case 0x269: map_key_clear(KEY_INSERT); break;
case 0x26a: map_key_clear(KEY_DELETE); break;
case 0x279: map_key_clear(KEY_REDO); break;
case 0x289: map_key_clear(KEY_REPLY); break;
case 0x28b: map_key_clear(KEY_FORWARDMAIL); break;
case 0x28c: map_key_clear(KEY_SEND); break;
default: goto ignore;
}
break;
通过 map_key_clear 宏将原始键值（usage->hid & HID_USAGE）转换成内核的定义，映射函数的具体实现可看内核源码，
以上键值的定义在 include/uapi/linux/input-event-codes.h （内核代码,较新版本定义整合进了input.h），对应到Android系统层的头文件则是 bionic/libc/kernel/uapi/linux/input-event-codes.h：
#define KEY_RESERVED 0
#define KEY_ESC 1
#define KEY_1 2
#define KEY_2 3
#define KEY_3 4
#define KEY_4 5
#define KEY_5 6
#define KEY_6 7
#define KEY_7 8
#define KEY_8 9
#define KEY_9 10
#define KEY_0 11
#define KEY_MINUS 12
#define KEY_EQUAL 13
#define KEY_BACKSPACE 14
#define KEY_TAB 15
#define KEY_Q 16
#define KEY_W 17
#define KEY_E 18
#define KEY_R 19
#define KEY_T 20
#define KEY_Y 21
#define KEY_U 22
#define KEY_I 23
#define KEY_O 24
#define KEY_P 25
#define KEY_LEFTBRACE 26
#define KEY_RIGHTBRACE 27
#define KEY_ENTER 28
#define KEY_LEFTCTRL 29
#define KEY_A 30
#define KEY_S 31
#define KEY_D 32
#define KEY_F 33
#define KEY_G 34
#define KEY_H 35
#define KEY_J 36
#define KEY_K 37
#define KEY_L 38
#define KEY_SEMICOLON 39
#define KEY_APOSTROPHE 40
#define KEY_GRAVE 41
#define KEY_LEFTSHIFT 42
#define KEY_BACKSLASH 43
#define KEY_Z 44
#define KEY_X 45
#define KEY_C 46
#define KEY_V 47
#define KEY_B 48
#define KEY_N 49
#define KEY_M 50
#define KEY_COMMA 51
#define KEY_DOT 52
#define KEY_SLASH 53
#define KEY_RIGHTSHIFT 54
#define KEY_KPASTERISK 55
#define KEY_LEFTALT 56
#define KEY_SPACE 57
#define KEY_CAPSLOCK 58
#define KEY_F1 59
#define KEY_F2 60
#define KEY_F3 61
#define KEY_F4 62
#define KEY_F5 63
#define KEY_F6 64
#define KEY_F7 65
#define KEY_F8 66
#define KEY_F9 67
#define KEY_F10 68
#define KEY_NUMLOCK 69
#define KEY_SCROLLLOCK 70
#define KEY_KP7 71
#define KEY_KP8 72
#define KEY_KP9 73
#define KEY_KPMINUS 74
#define KEY_KP4 75
#define KEY_KP5 76
#define KEY_KP6 77
#define KEY_KPPLUS 78
#define KEY_KP1 79
#define KEY_KP2 80
#define KEY_KP3 81
#define KEY_KP0 82
#define KEY_KPDOT 83
#define KEY_ZENKAKUHANKAKU 85
#define KEY_102ND 86
#define KEY_F11 87
#define KEY_F12 88
#define KEY_RO 89
#define KEY_KATAKANA 90
#define KEY_HIRAGANA 91
#define KEY_HENKAN 92
#define KEY_KATAKANAHIRAGANA 93
#define KEY_MUHENKAN 94
#define KEY_KPJPCOMMA 95
#define KEY_KPENTER 96
#define KEY_RIGHTCTRL 97
#define KEY_KPSLASH 98
#define KEY_SYSRQ 99
#define KEY_RIGHTALT 100
#define KEY_LINEFEED 101
#define KEY_HOME 102
#define KEY_UP 103
#define KEY_PAGEUP 104
#define KEY_LEFT 105
#define KEY_RIGHT 106
#define KEY_END 107
#define KEY_DOWN 108
#define KEY_PAGEDOWN 109
#define KEY_INSERT 110
#define KEY_DELETE 111
#define KEY_MACRO 112
#define KEY_MUTE 113
#define KEY_VOLUMEDOWN 114
#define KEY_VOLUMEUP 115
#define KEY_POWER 116 /* SC System Power Down */
#define KEY_KPEQUAL 117
#define KEY_KPPLUSMINUS 118
#define KEY_PAUSE 119
#define KEY_SCALE 120 /* AL Compiz Scale (Expose) */
#define KEY_KPCOMMA 121
#define KEY_HANGEUL 122
#define KEY_HANGUEL KEY_HANGEUL
#define KEY_HANJA 123
#define KEY_YEN 124
#define KEY_LEFTMETA 125
#define KEY_RIGHTMETA 126
#define KEY_COMPOSE 127
#define KEY_STOP 128 /* AC Stop */
#define KEY_AGAIN 129
#define KEY_PROPS 130 /* AC Properties */
#define KEY_UNDO 131 /* AC Undo */
#define KEY_FRONT 132
#define KEY_COPY 133 /* AC Copy */
#define KEY_OPEN 134 /* AC Open */
#define KEY_PASTE 135 /* AC Paste */
#define KEY_FIND 136 /* AC Search */
#define KEY_CUT 137 /* AC Cut */
#define KEY_HELP 138 /* AL Integrated Help Center */
#define KEY_MENU 139 /* Menu (show menu) */
#define KEY_CALC 140 /* AL Calculator */
#define KEY_SETUP 141
#define KEY_SLEEP 142 /* SC System Sleep */
#define KEY_WAKEUP 143 /* System Wake Up */
#define KEY_FILE 144 /* AL Local Machine Browser */
#define KEY_SENDFILE 145
#define KEY_DELETEFILE 146
#define KEY_XFER 147
#define KEY_PROG1 148
#define KEY_PROG2 149
#define KEY_WWW 150 /* AL Internet Browser */
#define KEY_MSDOS 151
#define KEY_COFFEE 152 /* AL Terminal Lock/Screensaver */
#define KEY_SCREENLOCK KEY_COFFEE
#define KEY_DIRECTION 153
#define KEY_CYCLEWINDOWS 154
#define KEY_MAIL 155
#define KEY_BOOKMARKS 156 /* AC Bookmarks */
#define KEY_COMPUTER 157
#define KEY_BACK 158 /* AC Back */
#define KEY_FORWARD 159 /* AC Forward */
#define KEY_CLOSECD 160
#define KEY_EJECTCD 161
#define KEY_EJECTCLOSECD 162
#define KEY_NEXTSONG 163
#define KEY_PLAYPAUSE 164
#define KEY_PREVIOUSSONG 165
#define KEY_STOPCD 166
#define KEY_RECORD 167
#define KEY_REWIND 168
#define KEY_PHONE 169 /* Media Select Telephone */
#define KEY_ISO 170
#define KEY_CONFIG 171 /* AL Consumer Control Configuration */
#define KEY_HOMEPAGE 172 /* AC Home */
#define KEY_REFRESH 173 /* AC Refresh */
#define KEY_EXIT 174 /* AC Exit */
#define KEY_MOVE 175
#define KEY_EDIT 176
#define KEY_SCROLLUP 177
#define KEY_SCROLLDOWN 178
#define KEY_KPLEFTPAREN 179
#define KEY_KPRIGHTPAREN 180
#define KEY_NEW 181 /* AC New */
#define KEY_REDO 182 /* AC Redo/Repeat */
#define KEY_F13 183
#define KEY_F14 184
#define KEY_F15 185
#define KEY_F16 186
#define KEY_F17 187
#define KEY_F18 188
#define KEY_F19 189
#define KEY_F20 190
#define KEY_F21 191
#define KEY_F22 192
#define KEY_F23 193
#define KEY_F24 194
#define KEY_PLAYCD 200
#define KEY_PAUSECD 201
#define KEY_PROG3 202
#define KEY_PROG4 203
#define KEY_DASHBOARD 204 /* AL Dashboard */
#define KEY_SUSPEND 205
#define KEY_CLOSE 206 /* AC Close */
#define KEY_PLAY 207
#define KEY_FASTFORWARD 208
#define KEY_BASSBOOST 209
#define KEY_PRINT 210 /* AC Print */
#define KEY_HP 211
#define KEY_CAMERA 212
#define KEY_SOUND 213
#define KEY_QUESTION 214
#define KEY_EMAIL 215
#define KEY_CHAT 216
#define KEY_SEARCH 217
#define KEY_CONNECT 218
#define KEY_FINANCE 219 /* AL Checkbook/Finance */
#define KEY_SPORT 220
#define KEY_SHOP 221
#define KEY_ALTERASE 222
#define KEY_CANCEL 223 /* AC Cancel */
#define KEY_BRIGHTNESSDOWN 224
#define KEY_BRIGHTNESSUP 225
#define KEY_MEDIA 226
#define KEY_SWITCHVIDEOMODE 227 /* Cycle between available video
outputs (Monitor/LCD/TV-out/etc) */
#define KEY_KBDILLUMTOGGLE 228
#define KEY_KBDILLUMDOWN 229
#define KEY_KBDILLUMUP 230
#define KEY_SEND 231 /* AC Send */
#define KEY_REPLY 232 /* AC Reply */
#define KEY_FORWARDMAIL 233 /* AC Forward Msg */
#define KEY_SAVE 234 /* AC Save */
#define KEY_DOCUMENTS 235
#define KEY_BATTERY 236
#define KEY_BLUETOOTH 237
#define KEY_WLAN 238
#define KEY_UWB 239
#define KEY_UNKNOWN 240
#define KEY_VIDEO_NEXT 241 /* drive next video source */
#define KEY_VIDEO_PREV 242 /* drive previous video source */
#define KEY_BRIGHTNESS_CYCLE 243 /* brightness up, after max is min */
#define KEY_BRIGHTNESS_AUTO 244 /* Set Auto Brightness: manual
brightness control is off,
rely on ambient */
#define KEY_BRIGHTNESS_ZERO KEY_BRIGHTNESS_AUTO
#define KEY_DISPLAY_OFF 245 /* display device to off state */
#define KEY_WWAN 246 /* Wireless WAN (LTE, UMTS, GSM, etc.) */
#define KEY_WIMAX KEY_WWAN
#define KEY_RFKILL 247 /* Key that controls all radios */
#define KEY_MICMUTE 248 /* Mute / unmute the microphone */
/* Code 255 is reserved for special needs of AT keyboard driver */
可通过 getevent 指令查看上报的键值，键值为十六进制显示：
首先要确定按键输入设备是对应/dev/input目录下哪个event，根据VID PID匹配对应的kl文件，可通过如下命令 cat /proc/bus/input/devices 查看设备信息：
shell@flo:/ $ cat /proc/bus/input/devices I: Bus=0000 Vendor=0000 Product=0000 Version=0000 N: Name="elan-touchscreen" P: Phys= S: Sysfs=/devices/virtual/input/input0 U: Uniq= H: Handlers=event0 cpufreq B: PROP=2 B: EV=b B: KEY=0 B: ABS=6618000 0 I: Bus=0000 Vendor=0000 Product=0000 Version=0000 N: Name="lid_input" P: Phys=/dev/input/lid_indev S: Sysfs=/devices/virtual/input/input1 U: Uniq= H: Handlers=event1 cpufreq B: PROP=0 B: EV=21 B: SW=1 I: Bus=0000 Vendor=0000 Product=0000 Version=0000 N: Name="apq8064-tabla-snd-card Button Jack" P: Phys=ALSA S: Sysfs=/devices/platform/soc-audio.0/sound/card0/input2 U: Uniq= H: Handlers=event2 cpufreq B: PROP=0 B: EV=3 B: KEY=ff 0 0 0 0 0 0 0 0 I: Bus=0000 Vendor=0000 Product=0000 Version=0000 N: Name="apq8064-tabla-snd-card Headset Jack" P: Phys=ALSA S: Sysfs=/devices/platform/soc-audio.0/sound/card0/input3 U: Uniq= H: Handlers=event3 cpufreq B: PROP=0 B: EV=21 B: SW=1c054 I: Bus=0000 Vendor=0000 Product=0000 Version=0000 N: Name="h2w button" P: Phys= S: Sysfs=/devices/virtual/input/input4 U: Uniq= H: Handlers=kbd event4 cpufreq B: PROP=0 B: EV=3 B: KEY=4 0 0 0 0 0 0 0 I: Bus=0019 Vendor=0001 Product=0001 Version=0100 N: Name="gpio-keys" P: Phys=gpio-keys/input0 S: Sysfs=/devices/platform/gpio-keys.0/input/input5 U: Uniq= H: Handlers=kbd event5 keychord cpufreq B: PROP=0 B: EV=3 B: KEY=1c0000 0 0 0 I: Bus=0005 Vendor=0030 Product=001D Version=0101 N: Name="Smart Remote" P: Phys= S: Sysfs=/devices/virtual/misc/uhid/input7 U: Uniq= H: Handlers=sysrq kbd event6 keychord cpufreq B: PROP=0 B: EV=10001f B: KEY=4837fff 72ff32d bf544446 0 0 1 30f90 8b17c007 ffff7bfa d9415fff febeffdf ffefffff ffffffff fffffffe B: REL=40 B: ABS=1 0 B: MSC=10
如上我的设备名是："Smart Remote" ， VID PID信息是：Vendor=0030 Product=001D ,则对应 /system/usr/keylayout/Vendor_0030_Product_001D.kl,如果该目录下没有对应VID PID的.kl则默认使用 Generic.kl，根据系统差异可能另外有 /data/system/devices/keylayout/Vendor_XXXX_Product_XXXX_Version_XXXX.kl ，此外还有键值对应字符的转换表：/system/usr/keychars/Generic.kcm 。
所以上面通过getevent获得的原始键值是0x44(十进制：68)，然后由 hid-input.c 可知 hid_keyboard[68]=87 而 input.h 中定义是 #define KEY_F11 87，所以Android系统层获取到内核转换后的键值为<87>，然后通过加载Generic.kl解析<87>的含义是"F11"（一般都是和内核头文件定义相匹配，也可以自己修改使其映射成其他含义）:
# # Generic key layout file for full alphabetic US English PC style external keyboards. # # This file is intentionally very generic and is intended to support a broad rang of keyboards. # Do not edit the generic key layout to support a specific keyboard; instead, create # a new key layout file with the required keyboard configuration. # key 1 ESCAPE key 2 1 key 3 2 key 4 3 key 5 4 key 6 5 key 7 6 key 8 7 key 9 8 key 10 9 key 11 0 key 12 MINUS key 13 EQUALS key 14 DEL key 15 TAB key 16 Q key 17 W key 18 E key 19 R key 20 T key 21 Y key 22 U key 23 I key 24 O key 25 P key 26 LEFT_BRACKET key 27 RIGHT_BRACKET key 28 ENTER key 29 CTRL_LEFT key 30 A key 31 S key 32 D key 33 F key 34 G key 35 H key 36 J key 37 K key 38 L key 39 SEMICOLON key 40 APOSTROPHE key 41 GRAVE key 42 SHIFT_LEFT key 43 BACKSLASH key 44 Z key 45 X key 46 C key 47 V key 48 B key 49 N key 50 M key 51 COMMA key 52 PERIOD key 53 SLASH key 54 SHIFT_RIGHT key 55 NUMPAD_MULTIPLY key 56 ALT_LEFT key 57 SPACE key 58 CAPS_LOCK key 59 F1 key 60 F2 key 61 F3 key 62 F4 key 63 F5 key 64 F6 key 65 F7 key 66 F8 key 67 F9 key 68 F10 key 69 NUM_LOCK key 70 SCROLL_LOCK key 71 NUMPAD_7 key 72 NUMPAD_8 key 73 NUMPAD_9 key 74 NUMPAD_SUBTRACT key 75 NUMPAD_4 key 76 NUMPAD_5 key 77 NUMPAD_6 key 78 NUMPAD_ADD key 79 NUMPAD_1 key 80 NUMPAD_2 key 81 NUMPAD_3 key 82 NUMPAD_0 key 83 NUMPAD_DOT # key 84 (undefined) key 85 ZENKAKU_HANKAKU key 86 BACKSLASH key 87 F11 key 88 F12 key 89 RO # key 90 "KEY_KATAKANA" # key 91 "KEY_HIRAGANA" key 92 HENKAN key 93 KATAKANA_HIRAGANA key 94 MUHENKAN key 95 NUMPAD_COMMA key 96 NUMPAD_ENTER key 97 CTRL_RIGHT key 98 NUMPAD_DIVIDE key 99 SYSRQ key 100 ALT_RIGHT # key 101 "KEY_LINEFEED" key 102 MOVE_HOME key 103 DPAD_UP key 104 PAGE_UP key 105 DPAD_LEFT key 106 DPAD_RIGHT key 107 MOVE_END key 108 DPAD_DOWN key 109 PAGE_DOWN key 110 INSERT key 111 FORWARD_DEL # key 112 "KEY_MACRO" key 113 VOLUME_MUTE key 114 VOLUME_DOWN key 115 VOLUME_UP key 116 POWER WAKE key 117 NUMPAD_EQUALS # key 118 "KEY_KPPLUSMINUS" key 119 BREAK # key 120 (undefined) key 121 NUMPAD_COMMA key 122 KANA key 123 EISU key 124 YEN key 125 META_LEFT key 126 META_RIGHT key 127 MENU WAKE_DROPPED key 128 MEDIA_STOP # key 129 "KEY_AGAIN" # key 130 "KEY_PROPS" # key 131 "KEY_UNDO" # key 132 "KEY_FRONT" # key 133 "KEY_COPY" # key 134 "KEY_OPEN" # key 135 "KEY_PASTE" # key 136 "KEY_FIND" # key 137 "KEY_CUT" # key 138 "KEY_HELP" key 139 MENU WAKE_DROPPED key 140 CALCULATOR # key 141 "KEY_SETUP" key 142 POWER WAKE key 143 POWER WAKE # key 144 "KEY_FILE" # key 145 "KEY_SENDFILE" # key 146 "KEY_DELETEFILE" # key 147 "KEY_XFER" # key 148 "KEY_PROG1" # key 149 "KEY_PROG2" key 150 EXPLORER # key 151 "KEY_MSDOS" key 152 POWER WAKE # key 153 "KEY_DIRECTION" # key 154 "KEY_CYCLEWINDOWS" key 155 ENVELOPE key 156 BOOKMARK # key 157 "KEY_COMPUTER" key 158 BACK WAKE_DROPPED key 159 FORWARD key 160 MEDIA_CLOSE key 161 MEDIA_EJECT key 162 MEDIA_EJECT key 163 MEDIA_NEXT key 164 MEDIA_PLAY_PAUSE key 165 MEDIA_PREVIOUS key 166 MEDIA_STOP key 167 MEDIA_RECORD key 168 MEDIA_REWIND key 169 CALL # key 170 "KEY_ISO" key 171 MUSIC key 172 HOME # key 173 "KEY_REFRESH" # key 174 "KEY_EXIT" # key 175 "KEY_MOVE" # key 176 "KEY_EDIT" key 177 PAGE_UP key 178 PAGE_DOWN key 179 NUMPAD_LEFT_PAREN key 180 NUMPAD_RIGHT_PAREN # key 181 "KEY_NEW" # key 182 "KEY_REDO" # key 183 F13 # key 184 F14 # key 185 F15 # key 186 F16 # key 187 F17 # key 188 F18 # key 189 F19 # key 190 F20 # key 191 F21 # key 192 F22 # key 193 F23 # key 194 F24 # key 195 (undefined) # key 196 (undefined) # key 197 (undefined) # key 198 (undefined) # key 199 (undefined) key 200 MEDIA_PLAY key 201 MEDIA_PAUSE # key 202 "KEY_PROG3" # key 203 "KEY_PROG4" # key 204 (undefined) # key 205 "KEY_SUSPEND" # key 206 "KEY_CLOSE" key 207 MEDIA_PLAY key 208 MEDIA_FAST_FORWARD # key 209 "KEY_BASSBOOST" # key 210 "KEY_PRINT" # key 211 "KEY_HP" key 212 CAMERA key 213 MUSIC # key 214 "KEY_QUESTION" key 215 ENVELOPE # key 216 "KEY_CHAT" key 217 SEARCH # key 218 "KEY_CONNECT" # key 219 "KEY_FINANCE" # key 220 "KEY_SPORT" # key 221 "KEY_SHOP" # key 222 "KEY_ALTERASE" # key 223 "KEY_CANCEL" key 224 BRIGHTNESS_DOWN key 225 BRIGHTNESS_UP key 226 HEADSETHOOK key 256 BUTTON_1 key 257 BUTTON_2 key 258 BUTTON_3 key 259 BUTTON_4 key 260 BUTTON_5 key 261 BUTTON_6 key 262 BUTTON_7 key 263 BUTTON_8 key 264 BUTTON_9 key 265 BUTTON_10 key 266 BUTTON_11 key 267 BUTTON_12 key 268 BUTTON_13 key 269 BUTTON_14 key 270 BUTTON_15 key 271 BUTTON_16 key 288 BUTTON_1 key 289 BUTTON_2 key 290 BUTTON_3 key 291 BUTTON_4 key 292 BUTTON_5 key 293 BUTTON_6 key 294 BUTTON_7 key 295 BUTTON_8 key 296 BUTTON_9 key 297 BUTTON_10 key 298 BUTTON_11 key 299 BUTTON_12 key 300 BUTTON_13 key 301 BUTTON_14 key 302 BUTTON_15 key 303 BUTTON_16 key 304 BUTTON_A key 305 BUTTON_B key 306 BUTTON_C key 307 BUTTON_X key 308 BUTTON_Y key 309 BUTTON_Z key 310 BUTTON_L1 key 311 BUTTON_R1 key 312 BUTTON_L2 key 313 BUTTON_R2 key 314 BUTTON_SELECT key 315 BUTTON_START key 316 BUTTON_MODE key 317 BUTTON_THUMBL key 318 BUTTON_THUMBR # key 352 "KEY_OK" key 353 DPAD_CENTER # key 354 "KEY_GOTO" # key 355 "KEY_CLEAR" # key 356 "KEY_POWER2" # key 357 "KEY_OPTION" # key 358 "KEY_INFO" # key 359 "KEY_TIME" # key 360 "KEY_VENDOR" # key 361 "KEY_ARCHIVE" key 362 GUIDE # key 363 "KEY_CHANNEL" # key 364 "KEY_FAVORITES" # key 365 "KEY_EPG" key 366 DVR # key 367 "KEY_MHP" # key 368 "KEY_LANGUAGE" # key 369 "KEY_TITLE" # key 370 "KEY_SUBTITLE" # key 371 "KEY_ANGLE" # key 372 "KEY_ZOOM" # key 373 "KEY_MODE" # key 374 "KEY_KEYBOARD" # key 375 "KEY_SCREEN" # key 376 "KEY_PC" key 377 TV # key 378 "KEY_TV2" # key 379 "KEY_VCR" # key 380 "KEY_VCR2" # key 381 "KEY_SAT" # key 382 "KEY_SAT2" # key 383 "KEY_CD" # key 384 "KEY_TAPE" # key 385 "KEY_RADIO" # key 386 "KEY_TUNER" # key 387 "KEY_PLAYER" # key 388 "KEY_TEXT" # key 389 "KEY_DVD" # key 390 "KEY_AUX" # key 391 "KEY_MP3" # key 392 "KEY_AUDIO" # key 393 "KEY_VIDEO" # key 394 "KEY_DIRECTORY" # key 395 "KEY_LIST" # key 396 "KEY_MEMO" key 397 CALENDAR # key 398 "KEY_RED" # key 399 "KEY_GREEN" # key 400 "KEY_YELLOW" # key 401 "KEY_BLUE" key 402 CHANNEL_UP key 403 CHANNEL_DOWN # key 404 "KEY_FIRST" # key 405 "KEY_LAST" # key 406 "KEY_AB" # key 407 "KEY_NEXT" # key 408 "KEY_RESTART" # key 409 "KEY_SLOW" # key 410 "KEY_SHUFFLE" # key 411 "KEY_BREAK" # key 412 "KEY_PREVIOUS" # key 413 "KEY_DIGITS" # key 414 "KEY_TEEN" # key 415 "KEY_TWEN" key 429 CONTACTS # key 448 "KEY_DEL_EOL" # key 449 "KEY_DEL_EOS" # key 450 "KEY_INS_LINE" # key 451 "KEY_DEL_LINE" key 464 FUNCTION key 465 ESCAPE FUNCTION key 466 F1 FUNCTION key 467 F2 FUNCTION key 468 F3 FUNCTION key 469 F4 FUNCTION key 470 F5 FUNCTION key 471 F6 FUNCTION key 472 F7 FUNCTION key 473 F8 FUNCTION key 474 F9 FUNCTION key 475 F10 FUNCTION key 476 F11 FUNCTION key 477 F12 FUNCTION key 478 1 FUNCTION key 479 2 FUNCTION key 480 D FUNCTION key 481 E FUNCTION key 482 F FUNCTION key 483 S FUNCTION key 484 B FUNCTION # key 497 KEY_BRL_DOT1 # key 498 KEY_BRL_DOT2 # key 499 KEY_BRL_DOT3 # key 500 KEY_BRL_DOT4 # key 501 KEY_BRL_DOT5 # key 502 KEY_BRL_DOT6 # key 503 KEY_BRL_DOT7 # key 504 KEY_BRL_DOT8 # Keys defined by HID usages key usage 0x0c006F BRIGHTNESS_UP key usage 0x0c0070 BRIGHTNESS_DOWN # Joystick and game controller axes. # Axes that are not mapped will be assigned generic axis numbers by the input subsystem. axis 0x00 X axis 0x01 Y axis 0x02 Z axis 0x03 RX axis 0x04 RY axis 0x05 RZ axis 0x06 THROTTLE axis 0x07 RUDDER axis 0x08 WHEEL axis 0x09 GAS axis 0x0a BRAKE axis 0x10 HAT_X axis 0x11 HAT_Y
键值从底层上报到上层的流程简图如下：
图2：键值上报流程
从上图可以看到，framework层通过.kl文件将获取的键值转换成实际按键含义后，又会通过KeycodeLabel转换成相应的keycode,具体文件在：frameworks\native\include\input\KeycodeLabels.h(android 4.4.4源码)：
/* * Copyright (C) 2008 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef _LIBINPUT_KEYCODE_LABELS_H #define _LIBINPUT_KEYCODE_LABELS_H #includestruct KeycodeLabel { const char *literal; int value; }; static const KeycodeLabel KEYCODES[] = { { "SOFT_LEFT", 1 }, { "SOFT_RIGHT", 2 }, { "HOME", 3 }, { "BACK", 4 }, { "CALL", 5 }, { "ENDCALL", 6 }, { "0", 7 }, { "1", 8 }, { "2", 9 }, { "3", 10 }, { "4", 11 }, { "5", 12 }, { "6", 13 }, { "7", 14 }, { "8", 15 }, { "9", 16 }, { "STAR", 17 }, { "POUND", 18 }, { "DPAD_UP", 19 }, { "DPAD_DOWN", 20 }, { "DPAD_LEFT", 21 }, { "DPAD_RIGHT", 22 }, { "DPAD_CENTER", 23 }, { "VOLUME_UP", 24 }, { "VOLUME_DOWN", 25 }, { "POWER", 26 }, { "CAMERA", 27 }, { "CLEAR", 28 }, { "A", 29 }, { "B", 30 }, { "C", 31 }, { "D", 32 }, { "E", 33 }, { "F", 34 }, { "G", 35 }, { "H", 36 }, { "I", 37 }, { "J", 38 }, { "K", 39 }, { "L", 40 }, { "M", 41 }, { "N", 42 }, { "O", 43 }, { "P", 44 }, { "Q", 45 }, { "R", 46 }, { "S", 47 }, { "T", 48 }, { "U", 49 }, { "V", 50 }, { "W", 51 }, { "X", 52 }, { "Y", 53 }, { "Z", 54 }, { "COMMA", 55 }, { "PERIOD", 56 }, { "ALT_LEFT", 57 }, { "ALT_RIGHT", 58 }, { "SHIFT_LEFT", 59 }, { "SHIFT_RIGHT", 60 }, { "TAB", 61 }, { "SPACE", 62 }, { "SYM", 63 }, { "EXPLORER", 64 }, { "ENVELOPE", 65 }, { "ENTER", 66 }, { "DEL", 67 }, { "GRAVE", 68 }, { "MINUS", 69 }, { "EQUALS", 70 }, { "LEFT_BRACKET", 71 }, { "RIGHT_BRACKET", 72 }, { "BACKSLASH", 73 }, { "SEMICOLON", 74 }, { "APOSTROPHE", 75 }, { "SLASH", 76 }, { "AT", 77 }, { "NUM", 78 }, { "HEADSETHOOK", 79 }, { "FOCUS", 80 }, { "PLUS", 81 }, { "MENU", 82 }, { "NOTIFICATION", 83 }, { "SEARCH", 84 }, { "MEDIA_PLAY_PAUSE", 85 }, { "MEDIA_STOP", 86 }, { "MEDIA_NEXT", 87 }, { "MEDIA_PREVIOUS", 88 }, { "MEDIA_REWIND", 89 }, { "MEDIA_FAST_FORWARD", 90 }, { "MUTE", 91 }, { "PAGE_UP", 92 }, { "PAGE_DOWN", 93 }, { "PICTSYMBOLS", 94 }, { "SWITCH_CHARSET", 95 }, { "BUTTON_A", 96 }, { "BUTTON_B", 97 }, { "BUTTON_C", 98 }, { "BUTTON_X", 99 }, { "BUTTON_Y", 100 }, { "BUTTON_Z", 101 }, { "BUTTON_L1", 102 }, { "BUTTON_R1", 103 }, { "BUTTON_L2", 104 }, { "BUTTON_R2", 105 }, { "BUTTON_THUMBL", 106 }, { "BUTTON_THUMBR", 107 }, { "BUTTON_START", 108 }, { "BUTTON_SELECT", 109 }, { "BUTTON_MODE", 110 }, { "ESCAPE", 111 }, { "FORWARD_DEL", 112 }, { "CTRL_LEFT", 113 }, { "CTRL_RIGHT", 114 }, { "CAPS_LOCK", 115 }, { "SCROLL_LOCK", 116 }, { "META_LEFT", 117 }, { "META_RIGHT", 118 }, { "FUNCTION", 119 }, { "SYSRQ", 120 }, { "BREAK", 121 }, { "MOVE_HOME", 122 }, { "MOVE_END", 123 }, { "INSERT", 124 }, { "FORWARD", 125 }, { "MEDIA_PLAY", 126 }, { "MEDIA_PAUSE", 127 }, { "MEDIA_CLOSE", 128 }, { "MEDIA_EJECT", 129 }, { "MEDIA_RECORD", 130 }, { "F1", 131 }, { "F2", 132 }, { "F3", 133 }, { "F4", 134 }, { "F5", 135 }, { "F6", 136 }, { "F7", 137 }, { "F8", 138 }, { "F9", 139 }, { "F10", 140 }, //{ "F11", 141 }, { "F11", 546 }, { "F12", 142 }, { "NUM_LOCK", 143 }, { "NUMPAD_0", 144 }, { "NUMPAD_1", 145 }, { "NUMPAD_2", 146 }, { "NUMPAD_3", 147 }, { "NUMPAD_4", 148 }, { "NUMPAD_5", 149 }, { "NUMPAD_6", 150 }, { "NUMPAD_7", 151 }, { "NUMPAD_8", 152 }, { "NUMPAD_9", 153 }, { "NUMPAD_DIVIDE", 154 }, { "NUMPAD_MULTIPLY", 155 }, { "NUMPAD_SUBTRACT", 156 }, { "NUMPAD_ADD", 157 }, { "NUMPAD_DOT", 158 }, { "NUMPAD_COMMA", 159 }, { "NUMPAD_ENTER", 160 }, { "NUMPAD_EQUALS", 161 }, { "NUMPAD_LEFT_PAREN", 162 }, { "NUMPAD_RIGHT_PAREN", 163 }, { "VOLUME_MUTE", 164 }, { "INFO", 165 }, { "CHANNEL_UP", 166 }, { "CHANNEL_DOWN", 167 }, { "ZOOM_IN", 168 }, { "ZOOM_OUT", 169 }, { "TV", 170 }, { "WINDOW", 171 }, { "GUIDE", 172 }, { "DVR", 173 }, { "BOOKMARK", 174 }, { "CAPTIONS", 175 }, { "SETTINGS", 176 }, { "TV_POWER", 177 }, { "TV_INPUT", 178 }, { "STB_POWER", 179 }, { "STB_INPUT", 180 }, { "AVR_POWER", 181 }, { "AVR_INPUT", 182 }, { "PROG_RED", 183 }, { "PROG_GREEN", 184 }, { "PROG_YELLOW", 185 }, { "PROG_BLUE", 186 }, { "APP_SWITCH", 187 }, { "BUTTON_1", 188 }, { "BUTTON_2", 189 }, { "BUTTON_3", 190 }, { "BUTTON_4", 191 }, { "BUTTON_5", 192 }, { "BUTTON_6", 193 }, { "BUTTON_7", 194 }, { "BUTTON_8", 195 }, { "BUTTON_9", 196 }, { "BUTTON_10", 197 }, { "BUTTON_11", 198 }, { "BUTTON_12", 199 }, { "BUTTON_13", 200 }, { "BUTTON_14", 201 }, { "BUTTON_15", 202 }, { "BUTTON_16", 203 }, { "LANGUAGE_SWITCH", 204 }, { "MANNER_MODE", 205 }, { "3D_MODE", 206 }, { "CONTACTS", 207 }, { "CALENDAR", 208 }, { "MUSIC", 209 }, { "CALCULATOR", 210 }, { "ZENKAKU_HANKAKU", 211 }, { "EISU", 212 }, { "MUHENKAN", 213 }, { "HENKAN", 214 }, { "KATAKANA_HIRAGANA", 215 }, { "YEN", 216 }, { "RO", 217 }, { "KANA", 218 }, { "ASSIST", 219 }, { "BRIGHTNESS_DOWN", 220 }, { "BRIGHTNESS_UP", 221 }, { "MEDIA_AUDIO_TRACK", 222 }, // NOTE: If you add a new keycode here you must also add it to several other files. // Refer to frameworks/base/core/java/android/view/KeyEvent.java for the full list. { NULL, 0 } }; // NOTE: If you edit these flags, also edit policy flags in Input.h. static const KeycodeLabel FLAGS[] = { { "WAKE", 0x00000001 }, { "WAKE_DROPPED", 0x00000002 }, { "SHIFT", 0x00000004 }, { "CAPS_LOCK", 0x00000008 }, { "ALT", 0x00000010 }, { "ALT_GR", 0x00000020 }, { "MENU", 0x00000040 }, { "LAUNCHER", 0x00000080 }, { "VIRTUAL", 0x00000100 }, { "FUNCTION", 0x00000200 }, { NULL, 0 } }; static const KeycodeLabel AXES[] = { { "X", 0 }, { "Y", 1 }, { "PRESSURE", 2 }, { "SIZE", 3 }, { "TOUCH_MAJOR", 4 }, { "TOUCH_MINOR", 5 }, { "TOOL_MAJOR", 6 }, { "TOOL_MINOR", 7 }, { "ORIENTATION", 8 }, { "VSCROLL", 9 }, { "HSCROLL", 10 }, { "Z", 11 }, { "RX", 12 }, { "RY", 13 }, { "RZ", 14 }, { "HAT_X", 15 }, { "HAT_Y", 16 }, { "LTRIGGER", 17 }, { "RTRIGGER", 18 }, { "THROTTLE", 19 }, { "RUDDER", 20 }, { "WHEEL", 21 }, { "GAS", 22 }, { "BRAKE", 23 }, { "DISTANCE", 24 }, { "TILT", 25 }, { "GENERIC_1", 32 }, { "GENERIC_2", 33 }, { "GENERIC_3", 34 }, { "GENERIC_4", 35 }, { "GENERIC_5", 36 }, { "GENERIC_6", 37 }, { "GENERIC_7", 38 }, { "GENERIC_8", 39 }, { "GENERIC_9", 40 }, { "GENERIC_10", 41 }, { "GENERIC_11", 42 }, { "GENERIC_12", 43 }, { "GENERIC_13", 44 }, { "GENERIC_14", 45 }, { "GENERIC_15", 46 }, { "GENERIC_16", 47 }, // NOTE: If you add a new axis here you must also add it to several other files. // Refer to frameworks/base/core/java/android/view/MotionEvent.java for the full list. { NULL, -1 } }; #endif // _LIBINPUT_KEYCODE_LABELS_H
然后app可以通过如下方法获得对应键按下时的keyCode值，即“F11”对应获得的keyCode即为上面自定义的<546>：
public boolean onKeyDown(int keyCode, KeyEvent event) { //重写的键盘按下监听
alert("获取系统keyCode : "+ keyCode);
return super.onKeyDown(keyCode, event);
}
三、添加自定义的键值：
（1）Kernel层：
① include/uapi/linux/input.h 中添加: #define KEY_LXL 123
② drivers/hid/hid-input.c 中添加: case 0x188: map_key_clear(KEY_LXL); break; //其中0x188是HID设备上报的原始键值
（2）Android系统层：
① bionic/libc/kernel/uapi/linux/input-event-codes.h 中添加 ： #define KEY_LXL 123 //与kernel中头文件定义一致
② Generic.kl或Vendor_xxxx_Product_xxxx.kl文件中添加 ： key 123 LXL;
③ /frameworks/native/include/android/keycodes.h 中添加 ： AKEYCODE_LXL = 666，
④ /frameworks/native/include/input/KeycodeLabels.h 的KEYCODES[]数组中添加： { "LXL", 666 },
⑤ 在frameworks/base/core/res/res/values/attrs.xml 中添加 ：
⑥ 在frameworks/base/core/java/android/view/KeyEvent.java添加： public static final int KEYCODE_LXL= 666;
经过如上的步骤就将Linux驱动向上层抛出的"123"键值和Android系统中的KEYCODE_LXL <666>对应起来了，然后可以在Android的framework层的键值处理函数中，捕获按键事件，并进行相应自定义处理，具体在frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java 的interceptKeyBeforeQueueing()函数中实现。