/**
  * 预定场地
  *
  * @param userId
  * @param field
  * @param trainingTimeSt
  * @param duration
  * @return
  */
 public String fieldBook(
     String userId, String field, java.sql.Timestamp trainingTimeSt, int duration) {
   TrainingFieldDao dao = new TrainingFieldDao();
   TrainingField _field = dao.find(field);
   return resourceHold(
       _field.getId(), "FIELD", _field.getFieldName(), userId, trainingTimeSt, duration);
 }
 /**
  * 场地查询
  *
  * @return
  */
 public String findField() {
   TrainingFieldDao fieldDao = new TrainingFieldDao();
   return Utils.parseJson(fieldDao.findAll());
 }