我在使用JPA和Hibernate时遇到问题,但无法解决。
因此,这是我的applicationContext.xml:
<context:component-scan base-package="com.abt.fiifootballmanager">
<context:exclude-filter type="annotation"
expression="org.springframework.stereotype.Controller" />
</context:component-scan>
<jdbc:embedded-database type="HSQL" id="dataSource" />
<bean
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
id="emf">
<property name="packagesToScan" value="com.abt.fiifootballmanager.entity" />
<property name="dataSource" ref="dataSource" />
<property name="jpaProperties">
<props>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbm2ddl.auto">create</prop>
</props>
</property>
<property name="persistenceProvider">
<bean class="org.hibernate.jpa.HibernatePersistenceProvider" />
</property>
</bean>
<tx:annotation-driven transaction-manager="transactionManager"/>
<bean class="org.springframework.orm.jpa.JpaTransactionManager" id="transactionManager">
<property name="dataSource" value="dataSource"/>
</bean>
这是我的表演实体:
package com.abt.fiifootballmanager.entity;
import java.io.Serializable;
import javax.persistence.*;
import java.math.BigDecimal;
import java.util.List;
@Entity
@Table(name="PERFORMANCES")
@NamedQuery(name="Performance.findAll", query="SELECT p FROM Performance p")
public class Performance implements Serializable {
private static final long serialVersionUID = 1L;
@EmbeddedId
private PerformancePK id;
@Column(name="RED_CARD")
private BigDecimal redCard;
@Column(name="YELLOW_CARD")
private BigDecimal yellowCard;
@OneToOne(mappedBy="performance")
private GoalkeepingPerformance goalkeepingPerformance;
@OneToMany(mappedBy="performance")
private List<OutfieldPerformance> outfieldPerformances;
@ManyToOne
@JoinColumn(name="MATCH_ID")
private Match match;
@ManyToOne
@JoinColumn(name="PLAYER_ID")
private Player player;
...getters & setters }
这是我的嵌入式id类:
@Embeddable
public class PerformancePK implements Serializable {
//default serial version id, required for serializable classes.
private static final long serialVersionUID = 1L;
@Column(name="MATCH_ID", insertable=false, updatable=false)
private long matchId;
@Column(name="PLAYER_ID", insertable=false, updatable=false)
private long playerId;
... //getters and setters
所以,这些是我的类(class)。但是,当我想运行我的应用程序时,会遇到下一个异常:
1.Error creating bean with name 'emf' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory
2. Repeated column in mapping for entity: com.abt.fiifootballmanager.entity.Performance column: MATCH_ID (should be mapped with insert="false" update="false")
我认为第一个异常(exception)是由第二个异常(exception)引起的。那么,为什么我会得到“实体映射中的重复列?”。使用嵌入式id类是个好主意吗?
最佳答案
您的match
类中的两个变量player
和Performance
与嵌入式ID中的matchId
和playerId
映射到相同的列。如错误所述,它们“应与insert =“false” update =“false”“映射。
@ManyToOne
@JoinColumn(name="MATCH_ID", insertable = false, updatable = false)
private Match match;
@ManyToOne
@JoinColumn(name="PLAYER_ID", insertable = false, updatable = false)
private Player player;
这实质上使这些字段为只读,因此,如果更改了嵌入式ID中的值,则Hibernate仅知道更改
MATCH_ID
和PLAYER_ID
列,而如果match
或player
的值更改,则不会更改。