Hibernate中的OneToOne-未知的“ mappedBy”

Question

我正在休眠狀態下鍛煉，但自實施幾個小時以來一直失敗。 我在stackoverflow上閱讀了很多答案，並經歷了2個教程（mkyong和其他一些家伙），但是我不明白我在做什么。

我嘗試了很多事情，但是我總是org.hibernate.AnnotationException: Unknown mappedBy in: ch.myapp.model.Employee.office, referenced property unknown: ch.myapp.model.Office.EMPLOYEES相同的異常（ org.hibernate.AnnotationException: Unknown mappedBy in: ch.myapp.model.Employee.office, referenced property unknown: ch.myapp.model.Office.EMPLOYEES ）

如果有人能給我提示問題出在哪里，我將非常高興。

我正在使用此數據庫方案，並且嘗試在Office和Employee之間實現1：1（我知道這沒有多大意義）。

員工班

@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...
}

辦公室類

@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>

這是我得到的Stacktrace（前幾行）：

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中的mapBy值錯誤，應為以下內容：

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

Answer 2

1.確保屬性如下：

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

2. 確保吸氣劑如下：

   public Office getOffice() { return office; }

mappingBy批注引用屬性名稱，而不是列名稱。 另外，由於屬性是私有的，所以休眠通過其getter / setter訪問它們，因此您需要遵循約定（get，Camel Case等）。

Answer 3

mappedBy的值必須與引用類（包括大小寫）中的屬性名稱相同。

例如，

如果該屬性的名稱為employee ，則必須准確地編寫employee 。

如果該屬性的名稱為employeE ，則必須准確地編寫employeE 。

（getter函數的名稱正確）

Answer 4

檢查您的兩個實體是否都在persistence.xml