Question

我在休眠期间锻炼，而且我在实施OneToOne关系时已经失败了几个小时。我在stackoverflow上阅读了很多答案并经历了2个教程（mkyong和其他人），但我不知道我做错了什么。

我尝试了很多东西，但我总是遇到同样的异常（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问题所在的暗示，我会很高兴。

我正在使用this database scheme，我尝试在Office和员工之间实现1：1（我知道这并没有多大意义）。

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中：

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>

这是我得到的Stacktrace（前几行）：

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)

Answer 1

您在Employee.class中有错误的mappedBy值，它应该是以下内容：

fopen

Answer 2

1.确保属性如下：

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

确保 getter 如下：

public Office getOffice() { return office; }

mappedBy 注释是指属性名称，而不是列名称。此外，由于属性是私有的，hibernate通过getter / setter访问它们，因此你需要它遵循约定（get，Camel Case等）

Answer 3

mappedBy的值必须与引用类中的属性名称相同，包括其大小写。

例如，

如果属性的名称为employee，则必须准确撰写employee。

如果属性的名称为employeE，则必须准确撰写employeE。

（getter function＆＃39; s name is proper）

Answer 4

检查您的实体是否都在persistence.xml

Hibernate中的OneToOne - 未知＆＃34; mappedBy＆＃34;

4 个答案: