Could not obtain transaction-synchronized Session for current thread 错误的解决方法！

         BsTable bsTable = new BsTable();
 
 //        String time = request.getParameter("date");
         String time = Constant.getStringDate(0);
 
         Map<String, String> map = new HashMap<String, String>();
         map.put("attendanceDate", time);
 
         params.clear();
         params.putAll(map);
 
         StringBuilder strSQL = new StringBuilder("SELECT apply_user_name 'name', ");
         strSQL.append(" count(CASE WHEN type='1' THEN type END) 'field1', ");                //迟到
         strSQL.append(" count(CASE WHEN type='3' THEN type END) 'field3', ");                //未签到
         strSQL.append(" count(CASE WHEN type='4' THEN type END) 'field4', ");                //请假
         strSQL.append(" count(CASE WHEN type='5' THEN type END) 'field5', ");                //外出
         strSQL.append(" count(CASE WHEN leave_type='病假' THEN leave_type END) 'field10',");    //病假
         strSQL.append(" count(CASE WHEN leave_type='事假' THEN type END) 'field11' ");        //事假
         strSQL.append(" FROM t_sign_record_late ");
         strSQL.append(" WHERE attendance_date=:attendanceDate");
         strSQL.append(" GROUP BY apply_user_name ");
 
         List report_list = signRecordReportDao.findBySql(strSQL.toString(), params);
 
         String strSQL_count = "SELECT COUNT(*) FROM (" + strSQL.toString() + ") t";
         bsTable.setTotal(signRecordReportDao.countBySql(strSQL_count).longValue());
         bsTable.setRows(report_list);
 
         return bsTable;

SpringMVC + Hibernate，使用事务管理 Service 层。但是这段代码放在 controller 里面就会遇到错误！

解决方法就是把数据库的相关操作放在 Service 层，用事务来管理就不会出错了