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Hibernate中的OneToOne - 未知的“mappedBy”

javahibernatehibernate-mappingone-to-one
3

我正在使用Hibernate进行练习，但在实现一对一关系方面已经失败了好几个小时了。我在stackoverflow上阅读了很多答案，并完成了2个教程（mkyong和其他一些人），但我不知道哪里出错了。

我尝试了很多方法，但最终都会遇到同样的异常(org.hibernate.AnnotationException: Unknown mappedBy in: ch.myapp.model.Employee.office, referenced property unknown: ch.myapp.model.Office.EMPLOYEES)

如果有人能给我一个提示问题所在，我会非常高兴。

我正在使用这个数据库模式，并尝试在Office和Employee之间实现1:1的关系（我知道这没有太多意义）。

Employee.class

@Entity
@Table(name = "EMPLOYEES")
public class Employee {

    @Id
    @GeneratedValue
    @Column(name = "EMPLOYEENUMBER")
    private Integer employeeNumber;
    @Column(name = "FIRSTNAME")
    private String firstName;
    @Column(name = "LASTNAME")
    private String lastName;

    @Column(name = "EXTENSION")
    private String extension;
    @Column(name = "EMAIL")
    private String email;
    @Column(name = "JOBTITLE")
    private String jobTitle;
    @Column(name = "OFFICECODE")
    private String officeCode;

    // ACHTUNG, Test "EmployeeDataAccesTest -> loadEmployee()" greift auf einen
    // Null-Wert zurück. Null kann keinem primitiven Wert zugeordnet werden.
    @Column(name = "REPORTSTO")
    private Integer reportsto;

    @OneToOne(mappedBy = "EMPLOYEES", fetch = FetchType.EAGER)
    private Office office;

//Getters and setters without annotations...
}

Office.class

@Entity
@Table(name = "OFFICES")
public class Office {

    @Id
    @Column(name = "OFFICECODE")
    private String officeCode;
    @Column(name = "CITY")
    private String city;
    @Column(name = "PHONE")
    private String phone;
    @Column(name = "ADDRESSLINE1")
    private String addressLine1;
    @Column(name = "ADDRESSLINE2")
    private String addressLine2;
    @Column(name = "STATE")
    private String state;
    @Column(name = "COUNTRY")
    private String country;
    @Column(name = "POSTALCODE")
    private String postalCode;
    @Column(name = "TERRITORY")
    private String territory;

    @OneToOne
    @JoinColumn(name = "OFFICECODE")
    private Employee employee;

//Getters and setters without annotations...
}

Hibernate.cfg.xml:

l version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration SYSTEM "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.dialect">org.hibernate.dialect.DerbyDialect</property>
        <property name="hibernate.connection.driver_class">org.apache.derby.jdbc.EmbeddedDriver</property>
        <property name="hibernate.connection.url">jdbc:derby:/home/dev/dev/git/TestBusiness/myDB</property>
        <property name="hibernate.connection.username"></property>
        <property name="hibernate.connection.password"></property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        <property name="show_sql">true</property>
        <property name="hibernate.current_session_context_class">thread</property>

        <mapping class="ch.myapp.model.Office"/>
        <mapping class="ch.myapp.model.Employee"/>
    </session-factory>
</hibernate-configuration>

This is the Stacktrace I get (first couple of lines):

org.hibernate.AnnotationException: Unknown mappedBy in: ch.myapp.model.Employee.office, referenced property unknown: ch.myapp.model.Office.EMPLOYEES
    at org.hibernate.cfg.OneToOneSecondPass.doSecondPass(OneToOneSecondPass.java:154)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1659)
    at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1634)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:278)
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:692)
    at ch.myapp.HibernateManager.getSessionFactory(HibernateManager.java:44)
    at ch.myapp.HibernateManager.openCurrentSessionwithTransaction(HibernateManager.java:24)
    at ch.myapp.dataaccess.EmployeeDataAccess.load(EmployeeDataAccess.java:18)
    at ch.myapp.dataaccess.OfficeDataAccessTest.shouldLoadOffice(OfficeDataAccessTest.java:24)

你检查过包名是否为“ch.myapp.model.Employee”了吗？ - srikanth r
@srikanthr 嗯，包名是“ch.myapp.model”。嗯，我想知道是否这就是问题所在。 - codepleb
4个回答
7

1. 确保属性如下所示：

@OneToOne(mappedBy = "employee", fetch = FetchType.EAGER)
private Office office;

  1. 确保getter如下：

    public Office getOffice() { return office; }

mappedBy注解是指属性名称，而不是列名称。另外，由于属性是私有的，Hibernate 通过它们的 getter/setter 访问它们，因此需要遵循惯例（get，驼峰命名等）。

5
您在Employee.class中的mappedBy值错误，应更改为以下内容：
@OneToOne(mappedBy = "employee", fetch = FetchType.EAGER)
private Office office;
@TrudleR，你可以编辑你的问题并粘贴出现的错误，然后他是正确的，应该可以解决。同时，请粘贴你用于这两个相关属性的getter。可能会有一些问题，就是将“OFFICECODE”映射两次，一次作为Id，另一次不是，但那是另一个故事了。 - Deltharis
4

mappedBy的值必须与引用类中属性名称相同，包括大小写。

例如，如果属性名称是employee，则必须精确地写成employee。

如果属性名称是employeE，则必须精确地写成employeE。

（getter函数名称正确）

1

检查您的实体是否都在 persistence.xml 中

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