앱위젯은 RemoteViews를 사용하죠. 앱위젯의 클릭이벤트는 remoteView.setOnClickPendingIntent 를 사용합니다.

간단한 소스 몇줄 올려드려요 참고하세요. 저도 이때문에 고생좀 했네요.

public class LottoActivity extends AppWidgetProvider {
 
 public static final String ACTION_LOTTO = "lkm.lotto.LottoActivity.ACTION_LOTTO";

 
 public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
  
  super.onUpdate(context, appWidgetManager, appWidgetIds);
  final int N = appWidgetIds.length;
  for(int i=0; i<N; i++){
         int widgetID = appWidgetIds[i];
         
       
  RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget);
  
  PendingIntent update = PendingIntent.getBroadcast(context, 0, new Intent(ACTION_LOTTO), PendingIntent.FLAG_UPDATE_CURRENT);
  views.setOnClickPendingIntent(R.id.update_btn, update); //버튼 이벤트
  
  appWidgetManager.updateAppWidget(widgetID, views);
  }
 }
 
 

 @Override
 public void onReceive(Context context, Intent intent) {
  Log.e("KENJI", "ggggggggggggggggg");
   String action = intent.getAction();
  
   p(action.toString());
  
         if (AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) {
         }else if (AppWidgetManager.ACTION_APPWIDGET_DELETED.equals(action)) {
         }else if (AppWidgetManager.ACTION_APPWIDGET_ENABLED.equals(action)) {
         }else if (AppWidgetManager.ACTION_APPWIDGET_DISABLED.equals(action)) {
         }
        
         if(intent.getAction().equals(ACTION_LOTTO)){
          //위젯에서 버튼을 누르게되면 여길타요           
          
          Toast.makeText(context, "테스트중입니다.", Toast.LENGTH_SHORT).show();
          
         }
  super.onReceive(context, intent);
 }

 public void p(String msg){
  Log.d("", "lkm ------------>" + msg);
 }
 

 
}