使用Criteria創建分組統計查詢

//分組統計
ProjectionList projectionList = Projections.projectionList();
//group by  的屬性值
projectionList.add(Projections.groupProperty("os"));
//統計行數
projectionList.add(Projections.rowCount());

Criteria c = factory.openSession().createCriteria(AdClick.class);
//設置查詢條件		
c.setProjection(projectionList);