Java hibernate中的is-a关系

我正在尝试hibernate中Is-A关系的基本示例，但遇到了错误

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

我已经创建了Employee类的3个子类

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

雇员

被雇佣者

雇员

并使用（联接子类）标记建立关系

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

在此之前，我尝试了使用（子类）标记的相同示例，它工作得非常好，但现在使用（连接子类）错误正在显示。 除了xml标记外，我没有做任何更改。 我不知道我做错了什么

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

mysql.cfg.xml

 <!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    <hibernate-configuration>
    <session-factory>
     <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/hibernatedata</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.password">root</property>
    <property name="hibernate.connection.pool_size">10</property>
    <property name="show_sql">true</property>
    <property name="format_sql">true</property>
    <property name="hbm2ddl.auto">update</property>

    <mapping resource="resources/employee.hbm.xml"/>
    </session-factory>
    </hibernate-configuration>

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

异常日志：

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

        Sep 11, 2019 10:25:58 AM org.hibernate.Version logVersion
        INFO: HHH000412: Hibernate Core {5.4.4.Final}
        Sep 11, 2019 10:25:59 AM 

        org.hibernate.annotations.common.reflection.java.JavaReflectionManage                  
        <clinit>
        INFO: HCANN000001: Hibernate Commons Annotations {5.1.0.Final}
        Sep 11, 2019 10:26:01 AM 
        org.hibernate.engine.jdbc.connections.internal.
        DriverManagerConnectionProviderImpl configure
        WARN: HHH10001002: Using Hibernate built-in connection pool (not for 
        production use!)
        Sep 11, 2019 10:26:01 AM 
        org.hibernate.engine.jdbc.connections.internal.
        DriverManagerConnectionProviderImpl buildCreator
        INFO: HHH10001005: using driver [com.mysql.jdbc.Driver] at URL 
        [jdbc:mysql://localhost:3306/hibernatedata]
        Sep 11, 2019 10:26:01 AM 
        org.hibernate.engine.jdbc.connections.internal.
        DriverManagerConnectionProviderImpl buildCreator
        INFO: HHH10001001: Connection properties: {user=root, password=****}
        Sep 11, 2019 10:26:01 AM 
        org.hibernate.engine.jdbc.connections.internal.
        DriverManagerConnectionProviderImpl buildCreator
        INFO: HHH10001003: Autocommit mode: false
       Sep 11, 2019 10:26:01 AM 
       org.hibernate.engine.jdbc.connections.internal.
       DriverManagerConnectionProviderImpl$PooledConnections <init>
       INFO: HHH000115: Hibernate connection pool size: 10 (min=1)
       Sep 11, 2019 10:26:01 AM org.hibernate.dialect.Dialect <init>
       INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQLDialect
       Sep 11, 2019 10:26:03 AM org.hibernate.AssertionFailure <init>
       ERROR: HHH000099: an assertion failure occurred (this may indicate a 
       bug in Hibernate, but is more likely due to unsafe use of the 
       session): org.hibernate.AssertionFailure: Table hibernatedata.employee 
       not found
       Sep 11, 2019 10:26:03 AM 
       org.hibernate.engine.jdbc.connections.internal.
       DriverManagerConnectionProviderImpl$PoolState stop
      INFO: HHH10001008: Cleaning up connection pool 
      [jdbc:mysql://localhost:3306/hibernatedata]
      Exception in thread "main" org.hibernate.MappingException: Could not  
      instantiate persister 
      org.hibernate.persister.entity.JoinedSubclassEntityPersister
      at 
      org.hibernate.persister.internal.PersisterFactoryImpl.
      createEntityPersister(PersisterFactoryImpl.java:112)
      at 
      org.hibernate.persister.internal.PersisterFactoryImpl.
      createEntityPersister(PersisterFactoryImpl.java:77)
      at 
      org.hibernate.metamodel.internal.MetamodelImpl.
      initialize(MetamodelImpl.java:181)
     at org.hibernate.internal.SessionFactoryImpl.<init> 
     (SessionFactoryImpl.java:300)
     at 
     org.hibernate.boot.internal.
     SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:462)
     at 
    org.hibernate.cfg.Configuration.
    buildSessionFactory(Configuration.java:708)
    at 
    org.hibernate.cfg.Configuration.
    buildSessionFactory(Configuration.java:724)
    at test.Client_Relations.main(Client_Relations.java:17)
    Caused by: org.hibernate.AssertionFailure: Table hibernatedata.employee 
    not found
    at
    org.hibernate.persister.entity.AbstractEntityPersister.
    getTableId(AbstractEntityPersister.java:5541)
    at org.hibernate.persister.entity.JoinedSubclassEntityPersister.<init> 
    (JoinedSubclassEntityPersister.java:450)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at 
    sun.reflect.NativeConstructorAccessorImpl.newInstance
    (NativeConstructorAccessorImpl.java:62)
    at 
    sun.reflect.DelegatingConstructorAccessorImpl.
    newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at org.hibernate.persister.internal.PersisterFactoryImpl.
    createEntityPersister(PersisterFactoryImpl.java:96)
    ... 7 more

2019年9月11日上午10:25:58 org.hibernate.Version日志版本
信息：hh000412:Hibernate核心{5.4.4.Final}
2019年9月11日上午10:25:59
org.hibernate.annotations.common.reflection.java.JavaReflectionManager
信息：HCANN000001:Hibernate Commons注释{5.1.0.Final}
2019年9月11日上午10:26:01
org.hibernate.engine.jdbc.connections.internal。
DriverManager连接ProviderImpl配置
警告：HHH10001002:使用Hibernate内置连接池（不适用于
生产使用！）
2019年9月11日上午10:26:01
org.hibernate.engine.jdbc.connections.internal。
DriverManager连接ProviderImpl buildCreator
信息：HHH10001005:在URL处使用驱动程序[com.mysql.jdbc.driver]
[jdbc:mysql://localhost:3306/hibernatedata]
2019年9月11日上午10:26:01
org.hibernate.engine.jdbc.connections.internal。
DriverManager连接ProviderImpl buildCreator
信息：HHH10001001:连接属性：{user=root，password=***}
2019年9月11日上午10:26:01
org.hibernate.engine.jdbc.connections.internal。
DriverManager连接ProviderImpl buildCreator
信息：HHH10001003:自动提交模式：错误
2019年9月11日上午10:26:01
org.hibernate.engine.jdbc.connections.internal。
DriverManager连接ProviderImpl$PooledConnections
信息：HH000115:休眠连接池大小：10（最小值=1）
2019年9月11日上午10:26:01 org.hibernate.dialogue.dialogue
信息：HH000400:使用方言：org.hibernate.dialogue.mysqldialogue
2019年9月11日上午10:26:03 org.hibernate.AssertionFailure
错误：HH000099:发生断言失败（这可能表示
Hibernate中的错误，但更可能是由于不安全地使用
会话）：org.hibernate.AssertionFailure:表hibernatedata.employee
找不到
2019年9月11日上午10:26:03
org.hibernate.engine.jdbc.connections.internal。
DriverManager连接ProviderImpl$PoolState停止
信息：HHH10001008:清理连接池
[jdbc:mysql://localhost:3306/hibernatedata]
线程“main”org.hibernate.MappingException中的异常：无法
实例化持久器
org.hibernate.persister.entity.JoinedSubclassEntityPersister
在
org.hibernate.persister.internal.PersisterFactoryImpl。
createEntityPersister（PersisterFactoryImpl.java:112）
在
org.hibernate.persister.internal.PersisterFactoryImpl。
createEntityPersister（PersisterFactoryImpl.java:77）
在
org.hibernate.metamodel.internal.MetamodelImpl。
初始化（MetamodelImpl.java:181）
位于org.hibernate.internal.SessionFactoryImpl。
（SessionFactoryImpl.java:300）
在
org.hibernate.boot.internal。
SessionFactoryBuilderImpl.build（SessionFactoryBuilderImpl.java:462）
在
org.hibernate.cfg.Configuration。
buildSessionFactory（Configuration.java:708）
在
org.hibernate.cfg.Configuration。
buildSessionFactory（Configuration.java:724）
test.Client\u Relations.main（Client\u Relations.java:17）
原因：org.hibernate.AssertionFailure:表hibernatedata.employee
找不到
在
org.hibernate.persister.entity.AbstractEntityPersister。
getTableId（AbstractEntityPersister.java:5541）
位于org.hibernate.persister.entity.JoinedSubclassEntityPersister。
（JoinedSubassentitypersister.java:450）
位于sun.reflect.NativeConstructorAccessorImpl.newInstance0（本机方法）
在
sun.reflect.nativeConstructor附件mpl.newInstance
（NativeConstructorAccessorImpl.java:62）
在
sun.reflect.delegatingconstructor或accessorimpl。
newInstance（DelegatingConstructorAccessorImpl.java:45）
位于java.lang.reflect.Constructor.newInstance（Constructor.java:423）
位于org.hibernate.persister.internal.PersisterFactoryImpl。
createEntityPersister（PersisterFactoryImpl.java:96）
... 还有7个

此错误表明数据库中不存在表Employee

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

Caused by: org.hibernate.AssertionFailure: Table hibernatedata.employee 
    not found

您需要更换

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

    <property name="hbm2ddl.auto">update</property>

    <property name="hbm2ddl.auto">create</property>

更新

与

<joined-subclass name="beans.SEmployee" table="semployee" extends="beans.Employee">
<key column="id"></key>
<property name="tool"></property>
</joined-subclass>

<joined-subclass name="beans.HEmployee" table="hemployee" extends="beans.Employee">
<key column="id"></key>
<property name="wh"></property>
</joined-subclass>

<joined-subclass name="beans.AEmployee" table="aemployee" extends="beans.Employee">
<key column="id"></key>
<property name="server"></property>
</joined-subclass>
</class>
</hibernate-mapping>```

    <property name="hbm2ddl.auto">update</property>

    <property name="hbm2ddl.auto">create</property>

创建

该表是否存在？错误日志显示Table

hibernatedata.employee未找到

yes错误日志显示的正是：Table hibernatedata.employee未找到这是自我解释的，不是吗？但我提到了创建它应该在找不到表的情况下创建表。是的，但我尝试了“创建”和“验证”同样的错误也发生了。感谢yash，我尝试了创建和验证选项，正如我前面所说的，但它不起作用。发生了相同的错误。您的代码是否正在数据库中创建表@RehanQuaziok，所以我不知道怎么做，但我已经从employee.hbm.xml文件的class标记中删除了schema=“hibernatedata”属性，代码运行正常。如果你能解释一下为什么这是正确的。谢谢，问题是

jdbc:mysql://localhost:3306/hibernatedata

您已经在连接URL中提到了架构名称。所以hibernate从那里获取了模式。之前，它在hibernatedata模式中查找表hibernatedata.employee。因此，现在您从employee.hbm.xml文件中的class标记中删除了schema=“hibernatedata”属性。它将在hibernatedata模式中查找表employee@雷汉夸齐