北京电商网站建设外包,王烨萍,WordPress邮件代发,知名的网络推广说明地址#xff1a;http://docs.oracle.com/javaee/5/api/javax/persistence/MappedSuperclass.html 用来申明一个超类#xff0c;继承这个类的子类映射时要映射此类中的字段#xff0c;可以当做是对entity抽取封装的类。如果子类想重写此类的映射信息#xff0c;可以使用… 说明地址http://docs.oracle.com/javaee/5/api/javax/persistence/MappedSuperclass.html 用来申明一个超类继承这个类的子类映射时要映射此类中的字段可以当做是对entity抽取封装的类。如果子类想重写此类的映射信息可以使用 AttributeOverride and AssociationOverride annotations Java代码 Example: Concrete class as a mapped superclass MappedSuperclass public class Employee { Id protected Integer empId; Version protected Integer version; ManyToOne JoinColumn(nameADDR) 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(namePT_EMP) AssociationOverride(nameaddress, joincolumnsJoinColumn(nameADDR_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(nameWAGE) 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(); } } 分享到 转载于:https://www.cnblogs.com/toSeeMyDream/p/4606896.html
