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首先看touchscreen的kl文件

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key 158     BACK              VIRTUAL WAKE

key 102     HOME              VIRTUAL WAKE

key 580     APP_SWITCH        VIRTUAL WAKE

key 116     GESTURE_DOUBLE_CLICK             VIRTUAL  WAKE

key 46      GESTURE_C                 VIRTUAL WAKE

key 18      GESTURE_E                 VIRTUAL WAKE

key 31      GESTURE_S                 VIRTUAL WAKE

key 47      GESTURE_V                 VIRTUAL WAKE

key 17      GESTURE_W                 VIRTUAL WAKE

key 44      GESTURE_Z                 VIRTUAL WAKE

那么这个kl有啥用呢，众所周知，android kernel和framework是不同的两层，也就是说，kernel里认识的

key值是158之类的这种数字，这个158是scankode，它往framework上报的时候也只会报这样的数字，但是framework不认识这个数字是什么，所以framework需要先解析kl文件，map起来，这样kernel传值上来的时候才会知道到底是什么key，也就是说转换scancode 158变成KeyCodeLabel也就是BACK，然后back再转换成4这个keycode

首先

key 580     APP_SWITCH        VIRTUAL WAKE

这里的580是scancode，转换撑了APP_SWITCH这个keycodelabel

InputEventLabels.h里的

 DEFINE_KEYCODE(APP_SWITCH),

#define DEFINE_KEYCODE(key) { #key, AKEYCODE_##key }

这里拼接了AKEYCODE_APP_SWITCH

 

Keycodes.h (native\include\android):    AKEYCODE_APP_SWITCH      = 187,

KeyEvent.java (base\core\java\android\view):    public static final int KEYCODE_APP_SWITCH      = 187;

然后就变成了keycode 187