Ale*_*ich 5 java hibernate hibernate-mapping
亲爱的开发者.
我会问你一个我认为很难为我解决的问题,因为我不知道答案的基本原因,我的意思是什么？让我们来看看.JBoss文档中的关联没有得到全面的答案:为什么我应该使用JoinTable而不是Foreign Key,我不完全理解映射是如何工作的,我的意思是什么？我知道什么是关联是ManyToMany或ManyToOne等,以及它们的目标是什么,但它们如何工作和彼此协作不需要关于双向或单向或joinTable或关联的答案,我希望有链接,我可以找到有关我的两个问题的完整信息:
1)为什么我应该使用JoinTable而不是外键？
2)实体如何工作并相互协作(没有解释什么是多个等等关联和双向或单向关联)？
所以,我有一段代码,因为我误解了,我只是想插入数据我是MYSQL数据库:Name_INSTITUTION和TYPE_NAME(机构类型):*
我的实体类:
@Entity
@Table(name="INSTITUTION")
public class Institution implements Serializable{
private static final long serialVersionUID = -7636394097858726922L;
private int Id;
@Id
@GeneratedValue(strategy=IDENTITY)
@Column(name="ID")
public int getId() {
return Id;
}
public void setId(int id) {
Id = id;
}
private int Version;
@javax.persistence.Version
@Column(name="VERSION")
public int getVersion() {
return Version;
}
public void setVersion(int version) {
Version = version;
}
private String Name_Institution;
@Column(name="NAME_INSTITUTION")
public String getName_Institution() {
return Name_Institution;
}
public void setName_Institution(String name_Institution) {
Name_Institution = name_Institution;
}
private Type type_inInstitution;
@ManyToOne
@Cascade(org.hibernate.annotations.CascadeType.ALL)
@JoinTable(name="TYPE_INSTITUTION",
joinColumns=@JoinColumn(name="INSTITUTION_ID"),
inverseJoinColumns=@JoinColumn(name="TYPE_ID"))
public Type getType_inInstitution() {
return type_inInstitution;
}
public void setType_inInstitution(Type type_inInstitution) {
this.type_inInstitution = type_inInstitution;
}
}
我的第二个实体类:
@Entity
@Table(name="TYPE")
public class Type implements Serializable {
private static final long serialVersionUID = -4246217431412815552L;
private String type;
public Type(){}
public Type(String type) {
this.type = type;
}
private int Type_Id;
@Id
@GeneratedValue(strategy=IDENTITY)
@Column(name="ID")
public int getType_Id() {
return Type_Id;
}
public void setType_Id(int type_Id) {
Type_Id = type_Id;
}
private String Type_Name;
@Column(name="TYPE_NAME")
public String getType_Name() {
return Type_Name;
}
public void setType_Name(String type_Name) {
Type_Name = type_Name;
}
private int Version;
@Version
@Column(name="VERSION")
public int getVersion() {
return Version;
}
public void setVersion(int version) {
Version = version;
}
private Set<Institution> set_Institution_inType = new HashSet<Institution>();
@OneToMany
@JoinTable(name="TYPE_INSTITUTION", joinColumns=@JoinColumn(name="TYPE_ID"), inverseJoinColumns=@JoinColumn(name="INSTITUTION_ID"))
public Set<Institution> getSet_Institution_inType() {
return set_Institution_inType;
}
public void setSet_Institution_inType(Set<Institution> set_Institution_inType) {
this.set_Institution_inType = set_Institution_inType;
}
public void addType(Institution institution) {
institution.setType_inInstitution(this);
getSet_Institution_inType().add(institution);
}
}
DAO课程:
@Repository("daoInsertDataInterface")
@Transactional
public class InsertDataService implements DaoInsertDataInterface{
private org.apache.commons.logging.Log log= LogFactory.getLog(InsertDataService.class);
private SessionFactory sessionFactory;
public SessionFactory getSessionFactory() {
return sessionFactory;
}
@Resource(name="sessionFactory")
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
@Override
public Institution insertData(Institution institution) {
sessionFactory.getCurrentSession().saveOrUpdate(institution);
log.info(institution.getId());
return institution;
}
}
我的metada配置:
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName"><value>${jdbc.driverClassName}</value></property>
<property name="url"><value>${jdbc.connectionValues}</value></property>
<property name="username"><value>${jdbc.userName}</value></property>
<property name="password"><value>${jdbc.password}</value></property>
</bean>
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref ="sessionFactory"/>
</bean>
<context:property-placeholder location="connection.properties"/>
<tx:annotation-driven transaction-manager="transactionManager"/>
<context:component-scan base-package="edu.demidov.dom, edu.demidov.dao" />
<context:annotation-config />
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="dataSource" ref ="dataSource"/>
<property name="packagesToScan" value="edu.demidov.dom"/>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
<prop key="hibernate.max_fetch_depth">3</prop>
<prop key="hibernate.jdbc.fetch_size">50</prop>
<prop key="hibernate.jdbc.batch_size">10</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
而错误:
INFO: - org.springframework.beans.factory.xml.XmlBeanDefinitionReader从类路径资源[APP-context.xml中] INFO加载XML bean定义:org.springframework.context.annotation.ClassPathBeanDefinitionScanner - JSR-330"javax.inject.Named "注释发现和支持组件扫描INFO:org.springframework.context.support.GenericXmlApplicationContext - 清爽org.springframework.context.support.GenericXmlApplicationContext@c93274:启动日期[星期四05月09日11点38分23秒EDT 2013]; 上下文层次INFO的根:org.springframework.beans.factory.config.PropertyPlaceholderConfigurer - 装载属性从类路径资源文件[connection.properties] INFO:org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor - JSR-330"的javax. inject.Inject"注释发现支持自动装配信息:org.springframework.beans.factory.support.DefaultListableBeanFactory - 在org.springframework.beans.factory.support.DefaultListableBeanFactory@1b9c2f0预实例单身:定义豆[数据源,transactionManager的, org.springframework.beans.factory.config.PropertyPlaceholderConfigurer#0,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,组织. springframework.transaction.config.internalTransactionAdvisor,daoInsertDataInterface,org.springframework.context.annotation.internalConf igurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,SessionFactory对象,org.springframework.context. annotation.ConfigurationClassPostProcessor.importAwareProcessor];
工厂层次结构的根Hibernate:插入TYPE(TYPE_NAME,VERSION)值(？,？)WARN:org.hibernate.util.JDBCExceptionReporter - SQL错误:1048,SQLState:23000 ERROR:org.hibernate.util.JDBCExceptionReporter - Column' TYPE_NAME'不能 为null线程"main"中的异常org.hibernate.exception.ConstraintViolationException:无法在org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:96)处插入:[edu.demidov.dom.Type] Org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)org.hibernate.idsert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:64)org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.的java:2327)在org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2834)在org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)在org.hibernate.engine.ActionQueue.execute (ActionQueue.java:273)在org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:320)在org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)在org.hibernate.event.def.AbstractSaveEventListener .saveWithGeneratedId(AbstractSaveEventListener.java:129)在org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)在org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)在有机hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)在org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)在org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java: 685)在org.hibernate.engine.CascadingAct的org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:677)离子$ 5.cascade(CascadingAction.java:252)位于org.hibernate的org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392)org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335). engine.Cascade.cascadeProperty(Cascade.java:204)在org.hibernate.engine.Cascade.cascade(Cascade.java:161)在org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:450)在组织位于org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener)的org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)中的.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:282) .java:129)org.hibernate.eve上的org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)nt.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)在org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)在org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:685)在org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:677)在org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:673)在edu.demidov.dao.InsertDataService.insertData(InsertDataService.java:32 )在sun.reflect.NativeMethodAccessorImpl.invoke0(本机方法)在sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)在sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)在java.lang.reflect中. Method.invoke(Method.java:601)在org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)在org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183 )在org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)在org.springframework.transaction.interceptor.TransactionInterceptor $ 1.proceedWithInvocation(TransactionInterceptor.java:96)在org.springframework.transaction.interceptor.TransactionAspectSupport .invokeWithinTransaction(TransactionAspectSupport.java:260)在org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)在org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)在有机springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)在$ Proxy22.insertData(来源不明)在edu.demidov.dao.AppTEst.main(AppTEst.java:22) 引起的:com.mysql.jdbc .exceptions.jdbc4.MySQLIntegrityConstraintViolationException:在sun.reflect.NativeConstructorAccessor的sun.reflect.NativeConstructorAccessorImpl.newInstance0 (Native Method)中,列'TYPE_NAME'不能为null Impl.newInstance(NativeConstructorAccessorImpl.java:57)在sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)在java.lang.reflect.Constructor.newInstance(Constructor.java:525)在com.mysql.jdbc.Util .handleNewInstance(Util.java:411)at com.mysql.jdbc.Util.getInstance(Util.java:386)at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1041)com.mysql.jdbc. MysqlIO.checkErrorPacket(MysqlIO.java:4120)在com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052)在com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)在com.mysql.jdbc .MysqlIO.sqlQueryDirect(MysqlIO.java:2664)在com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2815)在com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)在com.mysql. jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2458)在com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2375)在com.mysql.jdbc.PreparedStatement.executeUpdate(准备 aredStatement.java:2359)在org.hibernate.id.IdentityGenerator $ GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:94)在org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:57)... 44多个SS
感谢你们.
为什么我应该使用JoinTable而不是外键？
你不应该。你有选择的权利。如果您更喜欢使用连接表，请使用连接表。如果您更喜欢使用连接列（子表中的外键），请使用连接列。如果您已有无法更改的架构，请选择与现有架构对应的选项。
实体如何工作以及如何相互协作
我不确定你的意思是什么。如果实体 School 与实体 Teacher 具有 OneToMany 关联，当您从会话中获取学校并询问其教师时，Hibernate 将从数据库中为您加载它们。如果您将一名教师添加到学校的教师集合中，Hibernate 将为您填充连接列或连接表。目标只是像操作存储在内存中的简单对象一样操作对象，并让 Hibernate 加载它们并将它们保存到数据库中。
现在关于异常和问题的标题，异常消息清楚地说明了这一点：
插入到 TYPE (TYPE_NAME, VERSION) 值 (?, ?) 警告：org.hibernate.util.JDBCExceptionReporter - SQL 错误：1048，SQLState：23000 错误：org.hibernate.util.JDBCExceptionReporter - 列“TYPE_NAME”不能为空
You're trying to insert an antity of type Type (what a badly chosen name!) with a null name. And the database column doesn't acept null. So you get this exception. Either change the table definition if null is a valid Type name, or fix your code to make sure you don't try to insert a null name.
Also, respect the Java naming conventions. Your code is really hard to read.
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