休眠一对多映射配置 [英] Hibernate one-to-many mapping configuration

问题描述

我是hibernate的新手，我试图通过级联加载和更新来实现一对多的关系。然而，我的代码总是生成 org.apache.jasper.JasperException：org.hibernate.MappingException：无法获取org.hibernate.persister.entity.SingleTableEntityPersister 异常的构造函数。你能看看我的尝试，并建议我做错了什么？

总体思路是有一个公司类，其中包含一组客户。在创建客户的新实例时，我将他添加到公司并坚持一切。

实体（仅显示相关部分，或者至少我希望如此）

  public class Company实现Serializable {
 
 private static final long serialVersionUID = 146243652; 
 
私人字符串ID; 
私人字符串名称; 
私人字符串网站; 
私人套餐< Customer>顾客; 
 ... getters，setters等
 
 public class Customer实现Serializable {
 private static final long serialVersionUID = 864235654; 
 
私人字符串名称; 
私人字符串姓氏; 
私人字符串地址; 
私人字符串ID; 
私人公司公司; 
  

customer.hbm.xml：

 < hibernate-mapping> 
< class name =wa2.entities.Customertable =CUSTOMER> 
< id column =IDname =idtype =java.lang.String/> 
< property column =NAMEname =nametype =java.lang.String/> 
< property column =SURNAMEname =surnametype =java.lang.String/> 
< property column =ADRESSname =adresstype =java.lang.String/> 
 
<多对一名称=COMPANYclass =wa2.entities.Company> 
< column name =COMPANY_IDnot-null =true>< / column> 
< /多对一> 
< / class> 
< / hibernate-mapping> 
  

company.hbm.xml：

 <？xml version =1.0encoding =UTF-8？> 
<！DOCTYPE hibernate-mapping PUBLIC -  // Hibernate / Hibernate映射DTD 3.0 // EN
http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd\"> ; 
< hibernate-mapping> 
< class name =wa2.entities.Companytable =COMPANY> 
< id column =IDname =idtype =java.lang.String/> 
< property column =NAMEname =nametype =java.lang.String/> 
< property column =WEBSITEname =websitetype =java.lang.String/> 
 
< set name =CUSTOMERStable =CUSTOMERfetch =select> 
< key> 
< column name =CUSTOMER_IDnot-null =true>< / column> 
< / key> 
<一对多课程=wa2.entities.Customer/> 
< / set> 
< / class> 
< / hibernate-mapping> 
  

保存客户（这在执行一对多关系之前就有效，所以我怀疑是否存在这个代码有什么问题）：

  Customer customer = new Customer（）; 
 
 String name = req.getParameter（name）; 
 customer.setName（name）; 
 String surname = req.getParameter（surname）; 
 customer.setSurname（surname）; 
 String adress = req.getParameter（adress）; 
 customer.setAdress（adress）; 
 
字符串companyID = req.getParameter（companyId）; 
 Company company = repository.loadCompany（companyID）; 
 customer.setCompany（company）; 
 
 String id = UUID.randomUUID（）。toString（）; 
 customer.setId（id）; 
 
 repository.saveCustomer（customer）; 
  

我希望我没有忘记任何相关部分。如果是这样，请告诉我，我会发布相关的代码。非常感谢您的帮助！

编辑：
感谢您的回应。我似乎错误地在首都写了这些名字。我改变了这一点，现在我得到未能懒惰地初始化一个角色集合：wa2.entities.Company.customers，无法初始化代理 - 没有会话

解决方案

因为这是一个映射异常，我想它会在会话工厂创建期间出现，而不是在保存时出现？另外，看到整个堆栈跟踪可能会有所帮助。您的异常可能是由于映射文件和Bean之间的属性名称不匹配造成的。请参阅无法获取org.hibernate.persister的构造函数。 entity.SingleTableEntityPersister 。

在您的代码中，您的名称属性值为

 <多对一名称=COMPANYclass =wa2.entities.Company> 
< column name =COMPANY_IDnot-null =true>< / column> 
< /多对一> 
  

和

 < set name =CUSTOMERStable =CUSTOMERfetch =select> 
< key> 
< column name =CUSTOMER_IDnot-null =true>< / column> 
< / key> 
<一对多课程=wa2.entities.Customer/> 
< / set> 
  

大写，而pojos中的属性被命名为company和customer。

I am new to hibernate and I am trying to implement one-to-many relationship with cascade loading and updating. However, my code always generates org.apache.jasper.JasperException: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister exception. Could you take a look on my attempt and suggest what am I doing wrong?

The general idea is that there is a Company class which contains set of customers. When creating new instance of customer, I add him to a company and persist everything.

Entities (only displaying relevant parts, or at least I hope so)

public class Company implements Serializable {

    private static final long serialVersionUID = 146243652;

    private String id;
    private String name;
    private String website;
    private Set<Customer> customers;
    ... getters, setters etc

public class Customer implements Serializable {
    private static final long serialVersionUID = 864235654;

    private String name;
    private String surname;
    private String adress;
    private String id;
    private Company company;

customer.hbm.xml:

<hibernate-mapping>
    <class name="wa2.entities.Customer" table="CUSTOMER">
        <id column="ID" name="id" type="java.lang.String" />
        <property column="NAME" name="name" type="java.lang.String" />
        <property column="SURNAME" name="surname" type="java.lang.String" />
        <property column="ADRESS" name="adress" type="java.lang.String" />

         <many-to-one name="COMPANY" class="wa2.entities.Company">
             <column name="COMPANY_ID" not-null="true"></column> 
         </many-to-one> 
    </class>
</hibernate-mapping>

company.hbm.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="wa2.entities.Company" table="COMPANY">
        <id column="ID" name="id" type="java.lang.String" />
        <property column="NAME" name="name" type="java.lang.String" />
        <property column="WEBSITE" name="website" type="java.lang.String" />

        <set name="CUSTOMERS" table="CUSTOMER" fetch="select">
            <key>
                <column name="CUSTOMER_ID" not-null="true"></column>
            </key>
            <one-to-many class="wa2.entities.Customer"/>
        </set>
    </class>
</hibernate-mapping>

Saving customer (this worked before the implementation of one-to-many relationship so I doubt that there is anything wrong with this code):

        Customer customer = new Customer();

        String name = req.getParameter("name");
        customer.setName(name);
        String surname = req.getParameter("surname");
        customer.setSurname(surname);
        String adress = req.getParameter("adress");
        customer.setAdress(adress);

        String companyID = req.getParameter("companyId");
        Company company = repository.loadCompany(companyID);
        customer.setCompany(company);

        String id = UUID.randomUUID().toString();
        customer.setId(id);

        repository.saveCustomer(customer);

I hope that I did not forget any relevant part. If so, please tell me and I will post the relevant code. Thank you very much for any help!

EDIT: Thanks for the responses. It seems that I wrote the names wrongly in capitals. I changed that and now I am getting failed to lazily initialize a collection of role: wa2.entities.Company.customers, could not initialize proxy - no Session

解决方案

since this is an mapping exception, i guess it comes up during session factory creation, and not when saving? also, seeing the whole stacktrace could help. your exception can be caused by a mismatch of property names between mapping file and beans. see Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister.

in your code you have the name attribute values in

<many-to-one name="COMPANY" class="wa2.entities.Company">
    <column name="COMPANY_ID" not-null="true"></column> 
</many-to-one>

and

<set name="CUSTOMERS" table="CUSTOMER" fetch="select">
     <key>
        <column name="CUSTOMER_ID" not-null="true"></column>
     </key>
     <one-to-many class="wa2.entities.Customer"/>
 </set>

in uppercase, while the properties in your pojos are named company and customer.

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