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我对 Hibernate、一对多关联和列表有疑问。在我的模型中，我有国家，对于每个国家，我都有多个描述该国家地址结构的信息。我想访问这些元素的列表。

这是我的班级国家：

public class Country {
  private Long id;
  private String name;
  private List<AddressElement> addressElementList = null;
  ...
}

我的班级地址元素：

public class AddressElement {
  private Long id;
  private int pos;
  private int line;
  private String name;
  private String mask;
  ...
}

我的映射：

<hibernate-mapping  package="org.devtutos.tuto5.domaine">
  <class  name="Country" table="tuto.COUNTRY">
    <id name="id" type="java.lang.Long" column="COUNTRY_ID" unsaved-value="null">
      <generator class="native">
        <param name="sequence">tuto.SEQ_COUNTRY</param>
      </generator>
    </id>
    <natural-id mutable="true">
      <property name="name" column="COUNTRY_NAME" type="java.lang.String"/>
    </natural-id>
    <list name="addressElementList" table="tuto.ADDRESS_ELEMENT" lazy="false">
      <key  foreign-key="country_address_element_fk">
        <column name="COUNTRY_ID" not-null="true"/>
      </key>
      <list-index>
        <column name="ADDRESS_ELEMENT_POS" not-null="true" />
      </list-index>
      <one-to-many class="AddressElement"/>
    </list>
  </class>
</hibernate-mapping>
<hibernate-mapping  package="org.devtutos.tuto5.domaine">
  <class name="AddressElement" table="tuto.ADDRESS_ELEMENT">
    <id name="id" type="java.lang.Long" column="ADDRESS_ELEMENT_ID" unsaved-value="null">
      <generator class="native">
        <param name="sequence">tuto.SEQ_ADDRESS_ELEMENT</param>
      </generator>
    </id>
    <property name="line" column="ADDRESS_ELEMENT_LINE" not-null="true" type="java.lang.Integer" />
    <property name="name" column="ADDRESS_ELEMENT_NAME" not-null="true" type="java.lang.String" />
    <property name="mask" column="ADDRESS_ELEMENT_TYPE_MASK" not-null="true" type="java.lang.String" />
    <property name="pos" column="ADDRESS_ELEMENT_POS" not-null="true" type="java.lang.Integer" />
  </class>
</hibernate-mapping>

这是我的代码：

criteria = getSessionFactory().getCurrentSession().createCriteria(Country.class);
criteria.add(Restrictions.eq("name", countryName));
criteria.setFetchMode("addressElementList",FetchMode.JOIN);
Country country = (Country) criteria.list().get(0);
if (country == null) {
  logger.log(Level.INFO, "ERREUR DE COHERENCE INTERNE : Pays '".concat(countryName).concat("'non trouvé:"));
} else {
  logger.log(Level.INFO, "Pays trouvé.");
  logger.log(Level.INFO, "Nom du Pays :".concat(country.getName()));
  logger.log(Level.INFO, "Code du Pays :".concat(String.valueOf(country.getId())));
  liste = country.getAddressElementList();
  logger.log(Level.INFO, "Taille de la liste des éléments d'adresse :".concat(String.valueOf(liste.size())));
  for (AddressElement elem : liste) {
    if (elem == null) {logger.log(Level.INFO, "L'élément d'adresse est null.");}
    logger.log(Level.INFO, "Element de la liste : ID = ".concat(String.valueOf(elem.getId())));    **** Line of the error
    logger.log(Level.INFO, "Element de la liste : POS = ".concat(String.valueOf(elem.getPos())));
    logger.log(Level.INFO, "Element de la liste : NOM = ".concat(elem.getName()));
  }
}

这是我的日志：

Hibernate: 
select 
this_.COUNTRY_ID as COUNTRY1_2_1_, 
this_.COUNTRY_NAME as COUNTRY2_2_1_, 
addressele2_.COUNTRY_ID as COUNTRY6_2_3_, 
addressele2_.ADDRESS_ELEMENT_ID as ADDRESS1_3_, 
addressele2_.ADDRESS_ELEMENT_POS as ADDRESS5_3_, 
addressele2_.ADDRESS_ELEMENT_ID as ADDRESS1_0_0_, 
addressele2_.ADDRESS_ELEMENT_LINE as ADDRESS2_0_0_, 
addressele2_.ADDRESS_ELEMENT_NAME as ADDRESS3_0_0_, 
addressele2_.ADDRESS_ELEMENT_TYPE_MASK as ADDRESS4_0_0_, 
addressele2_.ADDRESS_ELEMENT_POS as ADDRESS5_0_0_ 
from 
tuto.COUNTRY this_ left outer join tuto.ADDRESS_ELEMENT addressele2_ 
on this_.COUNTRY_ID=addressele2_.COUNTRY_ID 
where 
this_.COUNTRY_NAME=?
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Pays trouvé.
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Nom du Pays :FRANCE
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Code du Pays :1
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Taille de la liste des éléments d'adresse :4
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: L'élément d'adresse est null.
27 déc. 2012 16:19:09 org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() for servlet [tuto5] in context with path [/tuto-5] threw exception [Request processing failed; nested exception is org.springframework.webflow.execution.ActionExecutionException: Exception thrown executing [AnnotatedAction@3f610944 targetAction org.devtutos.tuto5.mvc.webflow.action.receptionAction@4dc6bbd3, attributes = map['method' -> 'enregistrerLUtilisateur']] in state 'enregistrerLUtilisateur' of flow 'reception' -- action execution attributes were 'map[[empty]]'] with root cause
java.lang.NullPointerException
at org.devtutos.tuto5.dao.CountryHibernate.getCountryByName(CountryHibernate.java:103)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
...
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:166)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)

我无法访问某个国家/地区的地址元素信息。我尝试了几件事：我打开了惰性模式并使用 JOIN 指定了一个获取模式，但它不起作用。最令人惊讶的是列表已填充（有 4 个元素）并且以下代码运行良好（因此，信息在数据库中，setter 和 getter 工作）：

logger.log(Level.INFO, "Lecture de tous les éléments d'adresse.");
criteria = getSessionFactory().getCurrentSession().createCriteria(AddressElement.class);
liste = criteria.list();
logger.log(Level.INFO, "Taille de la liste des éléments d'adresse : ".concat(String.valueOf(liste.size())));
for (AddressElement elem : liste){
  if (elem == null) {logger.log(Level.INFO, "L'élément d'adresse est null.");}
  logger.log(Level.INFO, "Element de la liste : ID = ".concat(String.valueOf(elem.getId())));
  logger.log(Level.INFO, "Element de la liste : POS = ".concat(String.valueOf(elem.getPos())));
  logger.log(Level.INFO, "Element de la liste : NOM = ".concat(elem.getName()));
}

这是这段代码的结果：

INFO: Lecture de tous les éléments d'adresse.
Hibernate: select this_.ADDRESS_ELEMENT_ID as ADDRESS1_0_0_, this_.ADDRESS_ELEMENT_LINE as ADDRESS2_0_0_, this_.ADDRESS_ELEMENT_NAME as ADDRESS3_0_0_, this_.ADDRESS_ELEMENT_TYPE_MASK as ADDRESS4_0_0_, this_.ADDRESS_ELEMENT_POS as ADDRESS5_0_0_ from tuto.ADDRESS_ELEMENT this_
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Taille de la liste des éléments d'adresse : 6
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : ID = 1
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : POS = 1
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : NOM = Code Postal
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : ID = 2
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : POS = 2
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : NOM = Ville
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : ID = 3
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : POS = 3
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : NOM = Batiment
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : ID = 4
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : POS = 1
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : NOM = District
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : ID = 5
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : POS = 2
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : NOM = Zone
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : ID = 6
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : POS = 1
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName
INFO: Element de la liste : NOM = City
27 déc. 2012 16:19:09 org.devtutos.tuto5.dao.CountryHibernate getCountryByName

我在第一次执行时注意到我的列表的大小是错误的（4 而不是 3）。在我的示例中， 的值为countryName“FRANCE”。这是我的表格的内容：

国家：

COUNTRY_ID      CONTRY_NAME 
1                    "FRANCE"
2                    "HYPERION"
3                    "ATLANTIS"

地址_元素：

ADDRESS_ELEMENT_ID      COUNTRY_ID       ADDRESS_ELEMENT_POS    ADDRESS_ELEMENT_NAME        ADDRESS_ELEMENT_MASK    ADDRESS_ELEMENT_LINE
1                       1               1                       "Code Postal"               "\d{5}"                 1
2                       1               2                       "Ville"                     "[A-Z\-]{1,50}"         1
3                       1               3                       "Batiment"                  "[A-F]"                 1
4                       2               1                       "District"                  "[A-Z]{1,20}"           1 
5                       2               2                       "Zone"                      "[A-5]{1,5}"            2
6                       3               1                       "City"                      "[A-Z]{1,9}"            1

我究竟做错了什么？我不明白为什么elem在第一次执行时为空。有人可以帮助我吗？

提前致谢。

祝新年快乐。;-)

4

2 回答 2

0

谢谢你的帮助！

这是 Country 实体的完整代码。只有getter和setter。hashCode() 和 equals(Object obj) 方法已由 Eclipse 自动生成。

package org.devtutos.tuto5.domaine;

import java.util.ArrayList;
import java.util.List;

public class Country {

    private Long id;
    private String name;
    private List<AddressElement> addressElementList = null;

    public Country(){}

    public Long getId() {
        return id;
    }  

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

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }   

    public void addAddressElement( int pos, int line, String name, String mask){
        addressElementList.add(new AddressElement(pos,line,name,mask));
    }

    public List<AddressElement> getAddressElementList() {
        return addressElementList;
    }

    public void setAddressElementList(List<AddressElement> addressElementList) {
        this.addressElementList = addressElementList;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((id == null) ? 0 : id.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
             return false;
        if (getClass() != obj.getClass())
            return false;
        Country other = (Country) obj;
        if (id == null) {
            if (other.id != null)
                return false;
        } else if (!id.equals(other.id))
            return false;
        return true;
    }
}

我不知道问题出在哪里。再次感谢...

于 2012-12-29T12:43:07.700 回答
0

您的列表由 column 索引ADDRESS_ELEMENT_POS。因此，如果 Hibernate 加载 country 的所有地址列表1，它将1在索引 1 处设置地址（因为它是ADDRESS_ELEMENT_POS该地址的值），2在索引 2 处设置地址，在索引 3 处设置地址 3。因为有没有地址ADDRESS_ELEMENT_POS = 0，列表的索引 0 将为空。

list-index将数据库中 ADDRESS_ELEMENT_POS 的值减 1，或在配置元素中添加以下属性： base="1". 请参阅http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html_single/#d0e10924。

于 2012-12-29T13:13:45.297 回答