private BroadcastReceiver mHomeKeyEventReceiver = new BroadcastReceiver() {
	String SYSTEM_REASON = "reason";
	String SYSTEM_HOME_KEY = "homekey";
	String SYSTEM_HOME_KEY_LONG = "recentapps";

	@Override
	public void onReceive(Context context, Intent intent) {
		String action = intent.getAction();
		if (action.equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) { // 监听home键
			String reason = intent.getStringExtra(SYSTEM_REASON);

			// 表示按了home键,程序到了后台
			Toast.makeText(context, "只能监听"+reason, Toast.LENGTH_SHORT).show();
		}
	}
};	
	
registerReceiver(mHomeKeyEventReceiver, new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS));


-------------

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
	switch (keyCode){
		case KeyEvent.KEYCODE_BACK:
			Toast.makeText(this, "拦截back", Toast.LENGTH_SHORT).show();
			return true;

		case KeyEvent.KEYCODE_HOME:
			Toast.makeText(this, "拦截home成功了吗", Toast.LENGTH_SHORT).show();
			return true;
	}
	return super.onKeyDown(keyCode, event);
}