在4412中，开发板上只有四个按键，我们可以根据产品的需求自定义按键的功能。
在KeyEvent.java这个文件中，可以通过发出按键的事件，上报给上层。让上层app或者服务去接收处理。比如，我们可以看到这样的代码：
注释写得非常清楚，按下按键后，可以发出键值，按下的时间等等，也可以通过Android广播的形式去发送这些事件。
/**
* Create a new key event.
*
* @param downTime The time (in {@link android.os.SystemClock#uptimeMillis})
* at which this key code originally went down.
* @param eventTime The time (in {@link android.os.SystemClock#uptimeMillis})
* at which this event happened.
* @param action Action code: either {@link #ACTION_DOWN},
* {@link #ACTION_UP}, or {@link #ACTION_MULTIPLE}.
* @param code The key code.
* @param repeat A repeat count for down events (> 0 if this is after the
* initial down) or event count for multiple events.
* @param metaState Flags indicating which meta keys are currently pressed.
* @param deviceId The device ID that generated the key event.
* @param scancode Raw device scan code of the event.
*/
public KeyEvent(long downTime, long eventTime, int action,
int code, int repeat, int metaState,
int deviceId, int scancode) {
mDownTime = downTime;
mEventTime = eventTime;
mAction = action;
mKeyCode = code;
mRepeatCount = repeat;
mMetaState = metaState;
mDeviceId = deviceId;
mScanCode = scancode;
}
那么，如果我们要修改一个按键做别的功能，我们可以修改按键的KeyCode。
接下来，我们看到这个文件开头定义了这么一个类：
public class KeyEvent extends InputEvent implements Parcelable {
/** Key code constant: Unknown key code. */
public static final int KEYCODE_UNKNOWN = 0;
/** Key code constant: Soft Left key.
* Usually situated below the display on phones and used as a multi-function
* feature key for selecting a software defined function shown on the bottom left
* of the display. */
public static final int KEYCODE_SOFT_LEFT = 1;
/** Key code constant: Soft Right key.
* Usually situated below the display on phones and used as a multi-function
* feature key for selecting a software defined function shown on the bottom right
* of the display. */
public static final int KEYCODE_SOFT_RIGHT = 2;
/** Key code constant: Home key.
* This key is handled by the framework and is never delivered to applications. */
public static final int KEYCODE_HOME = 3;
/** Key code constant: Back key. */
public static final int KEYCODE_BACK = 4;
/** Key code constant: Call key. */
public static final int KEYCODE_CALL = 5;
.......
}
几乎所有相关的键值都被定义在这里，可以通过这个来修改键值或者添加键值。
该文件位于: /framework/base/core/java/android/view/KeyEvent.java
当然如果需要添加一个键值，那么还需要在这个文件中声明一个键值的枚举：
该文件位于：
/framwork/native/include/android/keycode.h
例如会看到以下代码：
#include <sys/types.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* Key codes.
*/
enum {
AKEYCODE_UNKNOWN = 0,
AKEYCODE_SOFT_LEFT = 1,
AKEYCODE_SOFT_RIGHT = 2,
AKEYCODE_HOME = 3,
AKEYCODE_BACK = 4,
AKEYCODE_CALL = 5,
AKEYCODE_ENDCALL = 6,
AKEYCODE_0 = 7,
AKEYCODE_1 = 8,
AKEYCODE_2 = 9,
AKEYCODE_3 = 10,
AKEYCODE_4 = 11,
AKEYCODE_5 = 12,
AKEYCODE_6 = 13,
AKEYCODE_7 = 14,
.....
};
需要
添加键值，就往下添加一个就行了，然后需要在一个xml文件里声明一下，这是Android的一个布局文件。
文件位于：/framework/base/core/res/res/values/attrs.xml
在文件大概1512行的地方会看到以下信息：
<!-- ========================== -->
<!-- Key Codes -->
<!-- ========================== -->
<eat-comment />
<!-- This enum provides the same keycode values as can be found in
{@link android.view.KeyEvent}. -->
<attr name="keycode">
<enum name="KEYCODE_UNKNOWN" value="0" />
<enum name="KEYCODE_SOFT_LEFT" value="1" />
<enum name="KEYCODE_SOFT_RIGHT" value="2" />
<enum name="KEYCODE_HOME" value="3" />
<enum name="KEYCODE_BACK" value="4" />
<enum name="KEYCODE_CALL" value="5" />
<enum name="KEYCODE_ENDCALL" value="6" />
<enum name="KEYCODE_0" value="7" />
<enum name="KEYCODE_1" value="8" />
<enum name="KEYCODE_2" value="9" />
<enum name="KEYCODE_3" value="10" />
<enum name="KEYCODE_4" value="11" />
<enum name="KEYCODE_5" value="12" />
<enum name="KEYCODE_6" value="13" />
<enum name="KEYCODE_7" value="14" />
<enum name="KEYCODE_8" value="15" />
<enum name="KEYCODE_9" value="16" />
<enum name="KEYCODE_STAR" value="17" />
<enum name="KEYCODE_POUND" value="18" />
<enum name="KEYCODE_DPAD_UP" value="19" />
<enum name="KEYCODE_DPAD_DOWN" value="20" />
<enum name="KEYCODE_DPAD_LEFT" value="21" />
.......
这些enum name就是刚刚在keycode.h里的枚举变量与value的声明。
那么Android又是怎么知道我按下的这个按键具体是什么按键呢？按键发出的事件为什么是这个值呢？所以，在这里就需要有一个Linux内核与Android的映射文件了。
通常，如果厂商没有定制这个映射文件，就会默认去使用:
/framework/base/data/keyboards/Generic.kl 这个文件。
但，在tiny4412中，友善之臂已经做了键值映射,这个文件就是tiny4412-key.kl
位于: device/friendly-arm/tiny4412/tiny4412-key.kl
我们可以来看看这个文件:
# Copyright (C) 2010 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.
key 158 BACK
key 230 SOFT_RIGHT
key 60 SOFT_RIGHT
key 107 ENDCALL
key 62 ENDCALL
key 229 MENU
key 139 MENU
key 59 MENU
key 127 SEARCH
key 217 SEARCH
key 228 POUND
key 227 STAR
key 231 CALL
key 61 CALL
key 232 DPAD_CENTER
key 108 DPAD_DOWN
key 103 DPAD_UP
key 102 HOME
key 105 DPAD_LEFT
key 106 DPAD_RIGHT
key 115 VOLUME_UP
key 114 VOLUME_DOWN
key 116 POWER
key 212 CAMERA
key 353 DPAD_CENTER
对应的，我们也可以找到kernel/include/linux/input.h中相关的键值定义：
这个文件里的键值就可以找到对应kl文件的键值。
大概在源码的186行可以看到:
/*
* Keys and buttons
*
* Most of the keys/buttons are modeled after USB HUT 1.12
* (see http://www.usb.org/developers/hidpage).
* Abbreviations in the comments:
* AC - Application Control
* AL - Application Launch Button
* SC - System Control
*/
#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_SYM 198
#define KEY_CENTER 199
#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_ZERO 244 /* brightness off, use ambient */
#define KEY_DISPLAY_OFF 245 /* display device to off state */
#define KEY_WIMAX 246
#define KEY_RFKILL 247 /* Key that controls all radios */
#define KEY_POUND 248
#define KEY_STAR 249
#define KEY_NETWORK 250
#define KEY_FOLDER_OPEN 251 /*only use Grande CHN CTC */
#define KEY_FOLDER_CLOSE 252 /*only use Grande CHN CTC */
#define KEY_3G 253 /*only use Grande CHN CTC */
/* Dummy touchkey code */
#define KEY_DUMMY_HOME1 249
#define KEY_DUMMY_HOME2 250
#define KEY_DUMMY_MENU 251
#define KEY_DUMMY_HOME 252
#define KEY_DUMMY_BACK 253
/* kona dummy touchkey */
#define KEY_DUMMY_1 251
#define KEY_DUMMY_2 252
#define KEY_DUMMY_3 253
(完)
