Android: How to create a button that produces the same result as hitting the down key on the D-Pad?

How do you create a button in an Android 开发者_开发知识库app that produces the same result as hitting the down key on the D-Pad?

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Send a key event of type KCODE_DPAD_DOWN. To send an event, you can use

InputMethodService.sendDownUpKeyEvents(keyEventCode);

See creating input method for more ways to send key events.