Step 5. ViewRoot.deliverKeyEventToViewHierarchy

　　[java] view plaincopyprint?

　　public final class ViewRoot extends Handler implements ViewParent，

　　View.AttachInfo.Callbacks {

　　......

　　private void deliverKeyEventToViewHierarchy(KeyEvent event， boolean sendDone) {

　　try {

　　if (mView != null && mAdded) {

　　final int action = event.getAction();

　　boolean isDown = (action == KeyEvent.ACTION_DOWN);

　　......

　　boolean keyHandled = mView.dispatchKeyEvent(event);

　　if (!keyHandled && isDown) {

　　int direction = 0;

　　switch (event.getKeyCode()) {

　　case KeyEvent.KEYCODE_DPAD_LEFT:

　　direction = View.FOCUS_LEFT;

　　break;

　　case KeyEvent.KEYCODE_DPAD_RIGHT:

　　direction = View.FOCUS_RIGHT;

　　break;

　　case KeyEvent.KEYCODE_DPAD_UP:

　　direction = View.FOCUS_UP;

　　break;

　　case KeyEvent.KEYCODE_DPAD_DOWN:

　　direction = View.FOCUS_DOWN;

　　break;

　　}

　　if (direction != 0) {

　　View focused = mView != null ? mView.findFocus() : null;

　　if (focused != null) {

　　View v = focused.focusSearch(direction);

　　......

　　if (v != null && v != focused) {

　　......

　　focusPassed = v.requestFocus(direction， mTempRect);

　　}

　　......

　　}

　　}

　　}

　　}

　　} finally {

　　if (sendDone) {

　　finishInputEvent();

　　}

　　......

　　}

　　}

　　......

　　}

　　public final class ViewRoot extends Handler implements ViewParent，

　　View.AttachInfo.Callbacks {

　　......

　　private void deliverKeyEventToViewHierarchy(KeyEvent event， boolean sendDone) {

　　try {

　　if (mView != null && mAdded) {

　　final int action = event.getAction();

　　boolean isDown = (action == KeyEvent.ACTION_DOWN);

　　......

　　boolean keyHandled = mView.dispatchKeyEvent(event);

　　if (!keyHandled && isDown) {

　　int direction = 0;

　　switch (event.getKeyCode()) {

　　case KeyEvent.KEYCODE_DPAD_LEFT:

　　direction = View.FOCUS_LEFT;

　　break;

　　case KeyEvent.KEYCODE_DPAD_RIGHT:

　　direction = View.FOCUS_RIGHT;

　　break;

　　case KeyEvent.KEYCODE_DPAD_UP:

　　direction = View.FOCUS_UP;

　　break;

　　case KeyEvent.KEYCODE_DPAD_DOWN:

　　direction = View.FOCUS_DOWN;

　　break;

　　}

　　if (direction != 0) {

　　View focused = mView != null ? mView.findFocus() : null;

　　if (focused != null) {

　　View v = focused.focusSearch(direction);

　　......

　　if (v != null && v != focused) {

　　......

　　focusPassed = v.requestFocus(direction， mTempRect);

　　}

　　......

　　}

　　}

　　}

　　}

　　} finally {

　　if (sendDone) {

　　finishInputEvent();

　　}

　　......

　　}

　　}

　　......

　　}

　　这个函数定义在文件frameworks/base/core/java/android/view/ViewRoot.java中。