在Android源代碼中，KeyEvent調度程序發送到onKeyDown的位置？

Question

在Android源代碼中，Android在從硬件接收到按鍵被按下的通知時調用onKeyDown()？

Answer 1

在KeyEvent.java

/** 
    * Deliver this key event to a {@link Callback} interface. If this is 
    * an ACTION_MULTIPLE event and it is not handled, then an attempt will 
    * be made to deliver a single normal event. 
    * 
    * @param receiver The Callback that will be given the event. 
    * @param state State information retained across events. 
    * @param target The target of the dispatch, for use in tracking. 
    * 
    * @return The return value from the Callback method that was called. 
    */ 
    public final boolean dispatch(Callback receiver, DispatcherState state, 
      Object target) { 
     switch (mAction) { 
      case ACTION_DOWN: { 
       mFlags &= ~FLAG_START_TRACKING; 
       if (DEBUG) Log.v(TAG, "Key down to " + target + " in " + state 
         + ": " + this); 
       boolean res = receiver.onKeyDown(mKeyCode, this); 
       if (state != null) { 
        if (res && mRepeatCount == 0 && (mFlags&FLAG_START_TRACKING) != 0) { 
         if (DEBUG) Log.v(TAG, " Start tracking!"); 
         state.startTracking(this, target); 
        } else if (isLongPress() && state.isTracking(this)) { 
         try { 
          if (receiver.onKeyLongPress(mKeyCode, this)) { 
           if (DEBUG) Log.v(TAG, " Clear from long press!"); 
           state.performedLongPress(this); 
           res = true; 
          } 
         } catch (AbstractMethodError e) { 
         } 
        } 
       } 
       return res; 
      }