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迈出使用 hibernate 和 postgres 的第一步,我为我的实体类创建了旧样式的 xml 配置,并创建了一些 dao 实现,如(Manning Java Persistence with Hib)一书中所述,并创建了一个 HibernateUtil 类来创建 SessionFactory。为了测试这些,我创建了一些实体并试图通过道来拯救。

在此代码中,客户类有一组“订单”。为了配置它,我创建了 hbm.xml 文件,如下所示。

在 demo() 方法中,我创建了实体实例并通过 dao 调用了 saveOrUpdate()。它成功运行并在 db 中创建了两个客户和一个订单。但是,当我尝试将订单添加到客户时,它会导致 RuntimeException 并回滚事务。当我尝试调试应用程序时,我发现

org.hibernate.context.ThreadLocalSessionContext.TransactionProtectionWrapper.invoke() ---> lang.reflect.Method.invoke() ---> java.lang.reflect.InvocationTargetException

我很困惑为什么会发生这种情况。如果我不调用 addOrdersToCustomers(),则不会发生此错误。如果我不调用该方法,这是否意味着客户对象没有订单集?在数据库中,订单表有一个 FK customer_id,它已成功设置为客户的 ID,因为 createOrders() 方法设置了客户客户实例的订单字段。但是,这不会更新客户的设置订单字段。

知道如何纠正这个问题吗?谢谢,

吉姆

public class Main {
    CustomerDao custdao;
    OrderDao orderdao;  
    Customer mark,jon;
    Order order1,order2,order3; 
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");

        public void demo()throws ParseException{
             custdao = Daofactory.getCustomerDao();
         orderdao = Daofactory.getOrderDao();
             createCustomers();
             createOrders();
             //addOrdersToCustomers();//uncommenting this causes RuntimeException
             updateEntities();
        }
        private  void updateEntities() {
            Transaction tx = null;
            Session session = HibernateUtil.getCurrentSession();
            logger.info("got session:"+session);
            try{
                tx = session.beginTransaction();
                logger.info("got transaxion:"+tx);

                custdao.saveOrUpdateCustomer(mark);         
                custdao.saveOrUpdateCustomer(jon);          
                orderdao.saveOrUpdateOrder(order1);     
                        tx.commit();
                 }catch(Exception e){
                    tx.rollback();
                 }
        }

       private void addOrdersToCustomers() {
        mark.getOrders().add(order1);
       }
       private void createCustomers() {
        mark = new Customer();
        mark.setName("mark");
        mark.setEmailAddress("mark@home");
        mark.setAddress("121,3rd avenue");
        mark.setCity("San Diego");
        mark.setState("CA");
        mark.setCountry("U.S.A");

        jon = new Customer();
        jon.setName("jon");
        jon.setEmailAddress("jon@home");
        jon.setAddress("1121 vpura");
        jon.setCity("bangalore");
        jon.setState("karnataka");
        jon.setCountry("india");

    }
    private void createOrders() throws ParseException {
        order1 = new Order();
        order1.setCustomer(mark);
        order1.setOrderNumber(Long.parseLong("111111111"));
        order1.setOrderDate(sdf.parse("2001/01/02"));
                ...  
    }
       ...
       public static void main(String[] args) throws ParseException {
        new Main().demo();

        }
    }

映射如下,

public class Customer {
    private Long customer_id;
    ...        
    private Set<Order> orders;
    public Customer() {
        super();
        orders = new HashSet<Order>();
    }
    ...
}

<hibernate-mapping package="org.me.hibernatestore">
 <class name="Customer" table="CUSTOMER">
  <id column="CUSTOMER_ID" name="customer_id"  type="java.lang.Long">
  <generator class="native"/>
  </id>  
...      
    <set name="orders" table="ORDERS" lazy="false" cascade="delete-orphan">
        <key column="CUSTOMER_ID"/>
        <one-to-many class="Order" />
    </set>    
 </class>
</hibernate-mapping>

订单.java

public class Order {
    private Long order_id;
    ...
    private Customer customer;
    ...
}

订单.hbm.xml

...
<class name="Order" table="ORDERS">
    <id name="order_id" column="ORDER_ID" type="long">
        <generator class="native"/>
    </id>
    ...
    <many-to-one name="customer" class="Customer" column="CUSTOMER_ID" lazy="false" />
...

dao 实现有一个基类

public class BaseDaoImpl<T, ID extends Serializable> implements BaseDao<T,ID>{
    private Class<T> persistentClass;
    private Session session;    
    public BaseDaoImpl() {
        this.persistentClass = (Class<T>)(((ParameterizedType)this.getClass().getGenericSuperclass()).getActualTypeArguments()[0]);
    }   
    public Session getSession() {
        if (session == null){           
            return HibernateUtil.getCurrentSession();
        }       
        return session;
    }
       ...
}

HibernateUtil.java

public class HibernateUtil {    
    private static SessionFactory sessionFactory;
    static {
        try {
            sessionFactory = new Configuration().configure().buildSessionFactory();         
        }catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
    public static Session getCurrentSession(){
        Session session = sessionFactory.getCurrentSession();       l
        return session;
    }
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1 回答 1

1

您的堆栈跟踪清楚地表明了原因 - 您正在尝试使用对瞬态对象的引用来保存对象。您要么需要在调用之前调用save()添加的对象,要么需要在类中的集合上添加(至少)持久级联。在您的 xml 情况下,这将更正OrderCustomerordersCustomer

<set name="orders" table="ORDERS" lazy="false" cascade="delete-orphan">

<set name="orders" table="ORDERS" lazy="false" cascade="delete-orphan,persist">
于 2011-07-27T14:23:41.907 回答