Java 按自定义对象休眠条件检索数据
任务是从数据库中检索特定列列表的数据,并作为已存在的自定义类返回 我尝试使用以下代码解决此任务:Java 按自定义对象休眠条件检索数据,java,hibernate,hibernate-criteria,Java,Hibernate,Hibernate Criteria,任务是从数据库中检索特定列列表的数据,并作为已存在的自定义类返回 我尝试使用以下代码解决此任务: public List<EntityOne> getServiceProviders(EntityTwo EntityTwo) { Criteria criteria = createCriteria(EntityOne.class); criteria.add(Restrictions.eq("EntityTwo", EntityTwo));
public List<EntityOne> getServiceProviders(EntityTwo EntityTwo) {
Criteria criteria = createCriteria(EntityOne.class);
criteria.add(Restrictions.eq("EntityTwo", EntityTwo));
criteria.createAlias("spid", "two");
criteria.addOrder(Order.asc("two.entityName"));
criteria.setProjection(Projections.projectionList()
.add(Projections.property("entityId"), "entityId")
.add(Projections.property("publishStatus"), "publishStatus")
.add(Projections.property("two.entityName"), "two.entityName")
.add(Projections.property("two.entityId"), "two.entityId")
);
return criteria.list();
}
公共列表getServiceProviders(EntityTwo EntityTwo){
Criteria=createCriteria(EntityOne.class);
标准。添加(限制。等式(“EntityTwo”,EntityTwo));
createAlias(“spid”、“两个”);
标准.addOrder(Order.asc(“two.entityName”));
criteria.setProjection(Projections.projectionList()的标准)
.add(Projections.property(“entityId”),“entityId”)
.add(Projections.property(“publishStatus”),“publishStatus”)
.add(Projections.property(“two.entityName”),“two.entityName”)
.add(Projections.property(“two.entityId”),“two.entityId”)
);
返回条件。list();
}
但是我收到了一个数据列表,这些数据没有按照我的要求分组到类中。您应该使用
Projections.groupProperty(propertyName)代码>
你的问题不是很清楚,尤其是当你试图使用Restrictions.eq(“EntityTwo”,EntityTwo)
时,因为这不会给出正确的结果。然而,Hibernate提供了一种从使用HibernateTransformers
类选择的列中返回对象的方法。在本例中,您将需要编写一个自定义类,其中包含要返回的列的getter setter
。请注意,变量的命名必须与别名列完全相同
由于您的示例不清楚,让我用一个简单的示例来说明:假设我需要所有采购OrderAmount
按OrderDate
和OrderNumber
分组
public static List<YourCustomEntity> getAggregateOrders(){
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction tx = null;
List<YourCustomEntity> list = new ArrayList<YourCustomEntity>();
try {
tx = session.beginTransaction();
Criteria cr = session.createCriteria(PurchaseOrders.class);
cr.setProjection(Projections.projectionList()
.add(Projections.sum("orderAmount").as("sumOrderAmount"))
.add(Projections.groupProperty("orderNumber").as("agOrderNumber"))
.add(Projections.groupProperty("orderDate").as("agOrderDate")));
cr.setResultTransformer(Transformers.aliasToBean(YourCustomEntity.class));
list = (List<YourCustomEntity>) cr.list();
}catch (Exception asd) {
System.out.println(asd.getMessage());
if (tx != null) {
tx.rollback();
}
} finally {
session.close();
}
return list;
}
NB:注意变量的命名与列别名相同
public static List<YourCustomEntity> getAggregateOrders(){
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction tx = null;
List<YourCustomEntity> list = new ArrayList<YourCustomEntity>();
try {
tx = session.beginTransaction();
Criteria cr = session.createCriteria(PurchaseOrders.class);
cr.setProjection(Projections.projectionList()
.add(Projections.sum("orderAmount").as("sumOrderAmount"))
.add(Projections.groupProperty("orderNumber").as("agOrderNumber"))
.add(Projections.groupProperty("orderDate").as("agOrderDate")));
cr.setResultTransformer(Transformers.aliasToBean(YourCustomEntity.class));
list = (List<YourCustomEntity>) cr.list();
}catch (Exception asd) {
System.out.println(asd.getMessage());
if (tx != null) {
tx.rollback();
}
} finally {
session.close();
}
return list;
}
public class YourCustomEntity {
private double sumOrderAmount;
private String agOrderNumber;
private Date agOrderDate;
//And then the getters and setters