Hibernate criteria interface setprojection method: sets the projection column of the query

setProjection(Projection projection)

Example 1

Criteria criteria = session.createCriteria(UserForm.class);  //示例化Criteria对象
criteria.setProjection(Projections.id());  //设置查询列
list = criteria.list();  //执行查询
Iterator it = list.iterator();  //获取查询结果迭代器
while(it.hasNext()){  //循环遍历查询结果
  System.out.println(it.next());
}

Example 2

Criteria criteria = session.createCriteria(UserForm.class);  //示例化Criteria对象
criteria.setProjection(Projections.projectionList()
                       .add(Projections.id())
                       .add(Projections.property("username"))  //查询数据表全部用户ID和用户名
                      );
List list = criteria.list();  //获取查询结果
Iterator it = list.iterator();  //获取查询结果迭代器
while(it.hasNext()){  //循环遍历迭代器
  Object[] o = (Object[])it.next();
  System.out.println("ID:"+o[0]+"用户名:"+o[1]);
}

Example 3

Criteria criteria = session.createCriteria(OrderForm.class);  //获取Criteria示例
criteria.setProjection(Projections.sum("money"));  //设置查询列
double sumMoney = (Double)criteria.uniqueResult();  //获取订单信息表总金额
System.out.println("合计金额:"+sumMoney);