AbstractService.java

package com.gffny.ldrbrd.common.service.impl;

import java.util.List;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.gffny.ldrbrd.common.dao.GenericDao;
import com.gffny.ldrbrd.common.exception.DataAccessException;
import com.gffny.ldrbrd.common.exception.ServiceException;

public class AbstractService {

	/** The Constant log. */
	static final Logger LOG = LoggerFactory.getLogger(AbstractService.class);

	/**
	 * Utility method to get the non-collection result of a named query (if
	 * there is intended to be only one result)
	 * 
	 * @param genericDao
	 * @param namedQuery
	 * @param params
	 * @return
	 */
	protected <T> T namedQuerySingleResultOrNull(GenericDao<T> genericDao,
			String namedQuery, Map<String, Object> params)
			throws ServiceException {

		// get the result list
		try {
			List<T> resultList = genericDao
					.findByNamedQuery(namedQuery, params);
			// check the result list validity
			if (resultList != null && resultList.size() == 1) {
				// if there's only one, return it
				return resultList.get(0);
			}
			// else kick up a fuss and return null
		} catch (DataAccessException e) {
			LOG.error(e.getMessage());
			throw new ServiceException(e);
		}
		return null;
	}

}