休眠中的映射列表<CustomClass> - ClassCastException

Posted 2023-02-27

【中文标题】休眠中的映射列表<CustomClass> - ClassCastException

【英文标题】：Mapping List<CustomClass> in hibernate - ClassCastException

【发布时间】：2012-07-15 05:50:16

【问题描述】：

我在休眠中映射列表时遇到困难。我想知道你对我的类、映射和数据库方案的看法。如果一切正常，我将不胜感激抛出异常的一些帮助。提前致谢！

我有以下课程：

public class AuditEntry 

    private long id;
    private String typeLigne;
    private String famille;
    private String user;
    private String libelle ;
    private String processName;
    private String caseId;
    private Date dateCreation = null;
    private List<AuditEntryStringMap> libelles;

    /* Getters and setters generated automatically... */


public class AuditEntryStringMap 

    private long id ;
    private String key ;
    private String value ;

    public AuditEntryStringMap(String key, String value) 
        this.key = key ;
        this.value = value ;
    
        /* Getters and setters generated automatically... */

我的 hbm 文件如下：

<class name="AuditEntryStringMap" table="AUDIT_I18N">

        <cache usage="read-write" include="all" />
        <id name="id" type="long">
            <column name="AUDIT_I18N_ID"></column>
            <generator class="sequence" >
            <param name="sequence">AUDIT_I18N_SEQ</param>
            </generator>
        </id>

        <property name="key" column="KEY_" />
        <property name="value" column="VALUE_"/>

</class>
<class name="AuditEntry" table="AUDIT">

        <cache usage="read-write" include="all" />
        <id name="id" type="long">
            <column name="AUDIT_ID"></column>
            <generator class="sequence" >
            <param name="sequence">AUDIT_SEQ</param>
            </generator>
        </id>

        <property name="typeLigne" column="TYPELIGNE" />

        <property name="libelle" column="LIBELLE" />

        <property name="user" column="USERNAME" />

        <property name="processName" column="PROCESSNAME" />

        <property name="caseId" column="CASE_ID" />

        <property name="dateCreation" insert="false" update="false">
            <column name="DCRE" sql-type="date" default="sysdate"></column>
        </property>

        <list name="libelles" table="AUDIT_I18N"> 
            <key> 
                <column name="FK_AUDIT_ID" sql-type="number(19,0)" /> 
            </key> 
            <index type="string" column="KEY_" /> 
            <element type="string" column="VALUE_" /> 
        </list>
    </class>

最后，我的sql脚本如下：

create sequence AUDIT_SEQ;
create sequence AUDIT_I18N_SEQ;

create table AUDIT (
    AUDIT_ID     number(19,0) not null,  
    TYPELIGNE    varchar2(255 char), 
    LIBELLE      varchar2(255 char),
    USERNAME     varchar2(255 char), 
    CASE_ID      varchar2(255 char),
    PROCESSNAME  varchar2(255 char), 
    DCRE          date default sysdate, 
    primary key (AUDIT_ID));

create table AUDIT_I18N (
    AUDIT_I18N_ID     number(19,0) not null, 
    KEY_              varchar2(255 char), 
    VALUE_            varchar2(255 char), 
    FK_AUDIT_ID       number(19, 0), 
    primary key (AUDIT_I18N_ID)) 

ALTER TABLE AUDIT_I18N add constraint FK_AUDIT_I18N foreign key (FK_AUDIT_ID) references AUDIT;

Hibernate 在提交时抛出异常之前会生成以下查询：

Hibernate: select AUDIT_SEQ.nextval from dual
Hibernate: insert into AUDIT (TYPELIGNE, LIBELLE, USERNAME, PROCESSNAME, CASE_ID, AUDIT_ID) values (?, ?, ?, ?, ?, ?)
Hibernate: insert into AUDIT_I18N (FK_AUDIT_ID, KEY_, VALUE_) values (?, ?, ?)

例外：

com.bpm.domain.AuditEntryStringMap cannot be cast to java.lang.String

当调用 GenericDaoHibernate.save(T entity) 时会发生这种情况。

【参考方案1】：

解决了使用集合而不是列表的问题...这在映射中：

<set name="libelles" lazy="extra" cascade="all-delete-orphan">
             <cache usage="read-write" include="all" />
             <key column="FK_AUDIT_ID"/>
             <one-to-many class="AuditEntryStringMap" />
</set>

另外，在 hibernate.cfg.xml 中没有引用我用于 AuditEntryStringMap 的 hbm。但仅此一项并不能解决列表标签的问题。

半个分辨率所以...如果有人知道它为什么不适用于列表，将不胜感激。