Hibernate查詢某個對象的某些屬性

1.特徵：查詢某個對象的一些屬性
fieldSQL = "distinct e.employeeinfoid,u.userid,u.departmentinfo.deptname"; 即：查詢的內容可以是對象.屬性，也可以是對象
tableSQL = " Userinfo u left join u.employeeinfo e "; 即：可以是一個表的對象
QueryResult<Object[]> q = employeeinfoManager.getScrollDateByHQL(startIndex, maxIndex,
fieldSQL, tableSQL, whereSQL, paramValues.toArray(),
orderby);


2.實現類


/*
 * 實體HQL分頁查詢
 * 
 * @param startIndex 分頁的起始位置
 * 
 * @param maxResult 每頁顯示的記錄數
 * 
 * @param searchField 所查詢的實體屬性
 * 
 * @param fromSQL 查詢的實體名稱
 * 
 * @param whereSQL 查詢條件
 * 
 * @param params 參數值
 * 
 * @param orderby 排序字段
 * 
 * @return QueryResult
 */
@SuppressWarnings("unchecked")
public QueryResult<Object[]> getScrollDateByHQL(int startIndex,
int maxResult, String searchField, String fromSQL, String whereSQL,
Object[] params, LinkedHashMap<String, String> orderby)
throws Exception {


QueryResult<Object[]> qr = new QueryResult<Object[]>();


Query query = null;
String where = (whereSQL != null && !"".equals(whereSQL.trim())) ? " where "
+ whereSQL
: "";
String nativeSQl = "select " + searchField + " from " + fromSQL + where
+ buildSqlOrderBy(orderby);


query = createQuery(nativeSQl, params);
if (startIndex != -1 && maxResult != -1)
query.setFirstResult(startIndex).setMaxResults(maxResult);
qr.setResultlist(query.list());
String countString = "";
if (searchField.indexOf("distinct") != -1) {
countString = "select " + searchField + " from " + fromSQL + where + "  ";
query = createQuery(countString, params);
qr.setTotalrecord(query.list().size());
} else {
countString = "select count(*) from " + fromSQL + where;
query = createQuery(countString, params);
qr.setTotalrecord(new Long(query.uniqueResult().toString()));
}
return qr;
}

/**
 * 生成排序SQL(原生)
 * 
 * @param orderby
 *            排序屬性
 */
private static String buildSqlOrderBy(LinkedHashMap<String, String> orderby) {
StringBuilder sb = new StringBuilder();
if (orderby != null && orderby.size() > 0) {
sb.append(" order by ");
for (String key : orderby.keySet()) {
sb.append(key).append(" ").append(orderby.get(key)).append(",");
}
sb.deleteCharAt(sb.length() - 1);
}
return sb.toString();
}


/**
 * HQL方式查詢
 * 
 * @param hql
 *            符合HQL語法的查詢語句
 * @param values
 *            數量可變的條件值,按順序綁定
 */
public Query createQuery(final String hql, final Object... values) {
Query query = super.getSession(true).createQuery(hql);


int j = values.length;
for (int i = 0; i < j; i++)
query.setParameter(i, values[i]);
return query;
}