异常: 分离的实体被传递给持久化

我已经成功地用 Hibernate 编写了我的第一个主子示例。几天后，我再次使用它，并升级了一些库。不知道我做了什么，但我再也不能让它运行了。有没有人能帮我找出代码中哪里出错了，并返回以下错误消息:

org.hibernate.PersistentObjectException: detached entity passed to persist: example.forms.InvoiceItem
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:127)
at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:799)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:791)
.... (truncated)

Hibernate 映射:

<hibernate-mapping package="example.forms">
<class name="Invoice" table="Invoices">
<id name="id" type="long">
<generator class="native" />
</id>
<property name="invDate" type="timestamp" />
<property name="customerId" type="int" />
<set cascade="all" inverse="true" lazy="true" name="items" order-by="id">
<key column="invoiceId" />
<one-to-many class="InvoiceItem" />
</set>
</class>
<class name="InvoiceItem" table="InvoiceItems">
<id column="id" name="itemId" type="long">
<generator class="native" />
</id>
<property name="productId" type="long" />
<property name="packname" type="string" />
<property name="quantity" type="int" />
<property name="price" type="double" />
<many-to-one class="example.forms.Invoice" column="invoiceId" name="invoice" not-null="true" />
</class>
</hibernate-mapping>

编辑: InvoiceManager.java

class InvoiceManager {


public Long save(Invoice theInvoice) throws RemoteException {
Session session = HbmUtils.getSessionFactory().getCurrentSession();
Transaction tx = null;
Long id = null;
try {
tx = session.beginTransaction();
session.persist(theInvoice);
tx.commit();
id = theInvoice.getId();
} catch (RuntimeException e) {
if (tx != null)
tx.rollback();
e.printStackTrace();
throw new RemoteException("Invoice could not be saved");
} finally {
if (session.isOpen())
session.close();
}
return id;
}


public Invoice getInvoice(Long cid) throws RemoteException {
Session session = HbmUtils.getSessionFactory().getCurrentSession();
Transaction tx = null;
Invoice theInvoice = null;
try {
tx = session.beginTransaction();
Query q = session
.createQuery(
"from Invoice as invoice " +
"left join fetch invoice.items as invoiceItems " +
"where invoice.id = :id ")
.setReadOnly(true);
q.setParameter("id", cid);
theInvoice = (Invoice) q.uniqueResult();
tx.commit();
} catch (RuntimeException e) {
tx.rollback();
} finally {
if (session.isOpen())
session.close();
}
return theInvoice;
}
}

Invoice.java

public class Invoice implements java.io.Serializable {


private Long id;
private Date invDate;
private int customerId;
private Set<InvoiceItem> items;


public Long getId() {
return id;
}


public Date getInvDate() {
return invDate;
}


public int getCustomerId() {
return customerId;
}


public Set<InvoiceItem> getItems() {
return items;
}


void setId(Long id) {
this.id = id;
}


void setInvDate(Date invDate) {
this.invDate = invDate;
}


void setCustomerId(int customerId) {
this.customerId = customerId;
}


void setItems(Set<InvoiceItem> items) {
this.items = items;
}
}

InvoiceItem.java

public class InvoiceItem implements java.io.Serializable {


private Long itemId;
private long productId;
private String packname;
private int quantity;
private double price;
private Invoice invoice;


public Long getItemId() {
return itemId;
}


public long getProductId() {
return productId;
}


public String getPackname() {
return packname;
}


public int getQuantity() {
return quantity;
}


public double getPrice() {
return price;
}


public Invoice getInvoice() {
return invoice;
}


void setItemId(Long itemId) {
this.itemId = itemId;
}


void setProductId(long productId) {
this.productId = productId;
}


void setPackname(String packname) {
this.packname = packname;
}


void setQuantity(int quantity) {
this.quantity = quantity;
}


void setPrice(double price) {
this.price = price;
}


void setInvoice(Invoice invoice) {
this.invoice = invoice;
}
}

编辑: 从客户端发送的 JSON 对象:

{"id":null,"customerId":3,"invDate":"2005-06-07T04:00:00.000Z","items":[
{"itemId":1,"productId":1,"quantity":10,"price":100},
{"itemId":2,"productId":2,"quantity":20,"price":200},
{"itemId":3,"productId":3,"quantity":30,"price":300}]}

编辑: 一些细节:
我试图通过以下两种方法来保存发票:

1. 上面提到的手工制作 Json 对象并将其传递给 Fresh 会话服务器。在这种情况下，绝对 在呼叫之前没有进行任何活动 保存方法，所以不应该有任何打开的会话 除了保存方法

中打开的那个

2. 加载现有数据 GetInvoice 方法，它们传递相同的 数据删除键值。这也是我相信 在保存为 事务正在 getInvoice 方法中提交

在这两种情况下，我都收到了相同的错误消息，迫使我相信休眠配置文件或实体类或保存方法出了问题。

请让我知道，如果我应该提供更多的细节