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## javax.persistence
Annotation Type MappedSuperclass

    @Target(value=TYPE)
    @Retention(value=RUNTIME)
    public @interface MappedSuperclass

Designates a class whose mapping information is applied to the entities that inherit from it. A mapped superclass has no separate table defined for it.

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) { ... }
        }

        Example: Non-entity superclass

        public class Cart {

            // This state is transient
            Integer operationCount;

            public Cart() { operationCount = 0; }
            public Integer getOperationCount() { return operationCount; }
            public void incrementOperationCount() { operationCount++; }
        }

        @Entity
        public class ShoppingCart extends Cart {

            Collection items = new Vector();

            public ShoppingCart() { super(); }

        ...

            @OneToMany
            public Collection getItems() { return items; }
            public void addItem(Item item) {
                items.add(item);
                incrementOperationCount();
            }
        }

Since:
  Java Persistence 1.0

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