public Integer selMaxLayerOfTable(String tbName) throws Exception {
StringBuffer sbSql = new StringBuffer();
sbSql.append("select Max(layer) from $tbName ");

    Sql sql = Sqls.queryEntity(sbSql.toString());
    sql.params().set("tbName", tbName);
    ****sql.setEntity(dao.getEntity(Integer.class));****
    dao.execute(sql);
    return sql.getInt();
}

加粗的部分报错。