保存新对象时Hibernate未知实体错误 [英] Hibernate unknown entity error when saving new object

问题描述

    Student s = (Student) db.getByID(Student.class,1);
    s.setFirstName("Preston");
    db.saveOrUpdate(s); <--Successful save
    s = new Student(){{setFirstName("asdf");setLastName("asdf1");}};
    s.setSchool((School) db.getByID(School.class, 1));
    db.saveOrUpdate(s); <--Error occurs 

线程main中的异常org.hibernate.MappingException：未知实体： project.databaseio.TestClass $ 1

Exception in thread "main" org.hibernate.MappingException: Unknown entity: project.databaseio.TestClass$1

public void saveOrUpdate(Object object)
{
    Transaction  tx = sessionFactory.getCurrentSession().beginTransaction();
    sessionFactory.getCurrentSession().saveOrUpdate(object);
    tx.commit();
}

堆栈跟踪

Exception in thread "main" org.hibernate.MappingException: Unknown entity: project.databaseio.TestClass$1
at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:548)
at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1338)
at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:180)
at org.hibernate.event.def.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:487)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:84)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:507)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:499)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:495)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:301)
at com.sun.proxy.$Proxy0.saveOrUpdate(Unknown Source)
at project.databaseio.DatabaseConnection.saveOrUpdate(DatabaseConnection.java:117)
at project.databaseio.TestClass.main(TestClass.java:21)

学生的Hibernate配置

Hibernate Config for Student

<hibernate-mapping>
    <class name="project.databaseio.Student" table="Student" catalog="fblaem">
        <id name="id" type="java.lang.Integer">
            <column name="id" />
            <generator class="identity" />
        </id>
        <many-to-one name="school" class="project.databaseio.School" fetch="select">
            <column name="SchoolID" not-null="true" />
        </many-to-one>
        <property name="firstName" type="string">
            <column name="FirstName" not-null="true" />
        </property>
        <property name="lastName" type="string">
            <column name="LastName" not-null="true" />
        </property>
        <property name="middleName" type="string">
            <column name="MiddleName" />
        </property>
        <property name="createDate" type="timestamp">
            <column name="CreateDate" length="0" />
        </property>
        <set name="studentEventTeams" table="StudentEventTeam" inverse="true" lazy="true" fetch="select">
            <key>
                <column name="StudentID" not-null="true" />
            </key>
            <one-to-many class="project.databaseio.StudentEventTeam" />
        </set>
    </class>
</hibernate-mapping>

推荐答案

问题来自以下行：

s = new Student(){{setFirstName("asdf");setLastName("asdf1");}};

简而言之，此行创建一个内部类的新实例，该实例隐式地从学生课程。这个类被Java编译器命名为 TestClass $ 1 ，并且因为没有映射，Hibernate正在抱怨它。你需要做的是：

Briefly this line is creating a new instance of an inner class which implicitly inherits from Student class. This class is named TestClass$1 by Java's compiler and because there is no mapping for that, Hibernate is complaining about it. What you need to do is:

s = new Student();
s.setFirstName("blah");
s.setLastName("blah2");
s.setSchool((School) db.getByID(School.class, 1));

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