new ScalarHandler()--＞返回值为long，不能用int接收！！！

public class ProductDaoImpl implements ProductDao {
    QueryRunner qr = new QueryRunner(DruidUtils.getDataSource());
    //根据tid返回每个种类的总数
    @Override
    public int findCountProduct(int tid) throws SQLException {
        String sql = "select count(1) from product where t_id = ?";
        int i = (int)qr.query(sql, new ScalarHandler(), tid);
        return i;
    }
}

public class MyTest {
    public static void main(String[] args) throws Exception {
        ProductDao productDao = new ProductDaoImpl();
        System.out.println(productDao.findCountProduct(1));
    }
}