@Documented @Target(value=TYPE) @Retention(value=RUNTIME) public @interface MappedSuperclass
A class designated with the MappedSuperclass
annotation can be mapped in the same way as an entity except that the
mappings will apply only to its subclasses since no table
exists for the mapped superclass itself. When applied to the
subclasses the inherited mappings will apply in the context
of the subclass tables. Mapping information may be overridden
in such subclasses by using the AttributeOverride
and
AssociationOverride
annotations or corresponding XML elements.
Example: Concrete class as a mapped superclass @MappedSuperclass public class Employee { @Id protected Integer empId; @Version protected Integer version; @ManyToOne @JoinColumn(name="ADDR") protected Address address; public Integer getEmpId() { ... } public void setEmpId(Integer id) { ... } public Address getAddress() { ... } public void setAddress(Address addr) { ... } } // Default table is FTEMPLOYEE table @Entity public class FTEmployee extends Employee { // Inherited empId field mapped to FTEMPLOYEE.EMPID // Inherited version field mapped to FTEMPLOYEE.VERSION // Inherited address field mapped to FTEMPLOYEE.ADDR fk // Defaults to FTEMPLOYEE.SALARY protected Integer salary; public FTEmployee() {} public Integer getSalary() { ... } public void setSalary(Integer salary) { ... } } @Entity @Table(name="PT_EMP") @AssociationOverride( name="address", joincolumns=@JoinColumn(name="ADDR_ID")) public class PartTimeEmployee extends Employee { // Inherited empId field mapped to PT_EMP.EMPID // Inherited version field mapped to PT_EMP.VERSION // address field mapping overridden to PT_EMP.ADDR_ID fk @Column(name="WAGE") protected Float hourlyWage; public PartTimeEmployee() {} public Float getHourlyWage() { ... } public void setHourlyWage(Float wage) { ... } }
AttributeOverride
,
AssociationOverride
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