KeyBord事件从Activtiy层往下分发详细过程代码示例

step1：调用Activity成员函数dispatchKeyEvent

public boolean dispatchKeyEvent(KeyEvent event) {

    // Let action bars open menus in response to the menu key prioritized over
    // the window handling it
    if (event.getKeyCode() == KeyEvent.KEYCODE_MENU &&
            mActionBar != null && mActionBar.onMenuKeyEvent(event)) {
        return true;
    }
    Window win = getWindow();
    if (win.superDispatchKeyEvent(event)) {
        return true;
    }
    View decor = mDecor;
    if (decor == null) decor = win.getDecorView();
    return event.dispatch(this, decor != null
            ? decor.getKeyDispatcherState() : null, this);
}

step2：Activity成员函数dispatchKeyEvent中调用phoneWindow的成员函数superDispatchKeyEvent

    Window win = getWindow();
    if (win.superDispatchKeyEvent(event)) {
        return true;
    }

setp3:在PhoneWindow的superDispatchKeyEvent函数中调用DecorView的成员函数uperDispatchKeyEvent

    public boolean superDispatchKeyEvent(KeyEvent event) {
        return mDecor.superDispatchKeyEvent(event);
    }

step4：ViewGroup的成员函数DispatchKeyEvent

private final class DecorView extends FrameLayout implements RootViewSurfaceTaker {

...    
public DecorView(Context context, int featureId) {
        super(context);
        mFeatureId = featureId;
    }
    @Override public boolean superDispatchKeyEvent(KeyEvent event) {

           if (super.dispatchKeyEvent(event)) {
               return true;
           }
...
}

step5：通过mFocused的包含关系实现隧道式分发

public boolean dispatchKeyEvent(KeyEvent event) {
    if (mInputEventConsistencyVerifier != null) {
        mInputEventConsistencyVerifier.onKeyEvent(event, 1);
    }

    if ((mPrivateFlags & (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS))
            == (PFLAG_FOCUSED | PFLAG_HAS_BOUNDS)) {
        if (super.dispatchKeyEvent(event)) {
            return true;
        }
    } else if (mFocused != null && (mFocused.mPrivateFlags & PFLAG_HAS_BOUNDS)
            == PFLAG_HAS_BOUNDS) {
        if (mFocused.dispatchKeyEvent(event)) {
            return true;
        }
    }

    if (mInputEventConsistencyVerifier != null) {
        mInputEventConsistencyVerifier.onUnhandledEvent(event, 1);
    }
    return false;
}