jpa
구체적인 클래스 상속 전략 당 테이블
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비고
- Vehicle, TransportationVehicle 및 PassengerVehicle은 추상 클래스이며 데이터베이스에는 별도의 테이블이 없습니다.
- 트럭, 자동차 및 자전거는 구체적인 클래스이므로 해당 테이블에 매핑됩니다. 이 테이블에는 @MappedSuperClass로 주석 된 클래스의 모든 필드가 포함되어야합니다. 데이터베이스에 해당 테이블이 없기 때문입니다.
- 따라서 Truck 테이블에는 TransportationVehicle 및 Vehicle에서 상속 된 필드를 저장할 열이 있습니다.
- 마찬가지로 자동차와 자전거에는 PassengerVehicle 및 Vehicle에서 상속 된 필드를 저장할 열이 있습니다.
구체적인 클래스 상속 전략 당 테이블
우리는 아래에 묘사 된 차량 계층 구조 예제를 취할 것입니다.
Vehicle.java
package com.thejavageek.jpa.entities;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.TableGenerator;
@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class Vehicle {
@TableGenerator(name = "VEHICLE_GEN", table = "ID_GEN", pkColumnName = "GEN_NAME", valueColumnName = "GEN_VAL", allocationSize = 1)
@Id
@GeneratedValue(strategy = GenerationType.TABLE, generator = "VEHICLE_GEN")
private int idVehicle;
private String manufacturer;
public int getIdVehicle() {
return idVehicle;
}
public void setIdVehicle(int idVehicle) {
this.idVehicle = idVehicle;
}
public String getManufacturer() {
return manufacturer;
}
public void setManufacturer(String manufacturer) {
this.manufacturer = manufacturer;
}
}
TransportationVehilcle.java
package com.thejavageek.jpa.entities;
import javax.persistence.MappedSuperclass;
@MappedSuperclass
public abstract class TransportationVehicle extends Vehicle {
private int loadCapacity;
public int getLoadCapacity() {
return loadCapacity;
}
public void setLoadCapacity(int loadCapacity) {
this.loadCapacity = loadCapacity;
}
}
Truck.java
package com.thejavageek.jpa.entities;
import javax.persistence.Entity;
@Entity
public class Truck extends TransportationVehicle {
private int noOfContainers;
public int getNoOfContainers() {
return noOfContainers;
}
public void setNoOfContainers(int noOfContainers) {
this.noOfContainers = noOfContainers;
}
}
PassengerVehicle.java
package com.thejavageek.jpa.entities;
import javax.persistence.MappedSuperclass;
@MappedSuperclass
public abstract class PassengerVehicle extends Vehicle {
private int noOfpassengers;
public int getNoOfpassengers() {
return noOfpassengers;
}
public void setNoOfpassengers(int noOfpassengers) {
this.noOfpassengers = noOfpassengers;
}
}
Car.java
package com.thejavageek.jpa.entities;
import javax.persistence.Entity;
@Entity
public class Car extends PassengerVehicle {
private int noOfDoors;
public int getNoOfDoors() {
return noOfDoors;
}
public void setNoOfDoors(int noOfDoors) {
this.noOfDoors = noOfDoors;
}
}
Bike.java
package com.thejavageek.jpa.entities;
import javax.persistence.Entity;
@Entity
public class Bike extends PassengerVehicle {
private int saddleHeight;
public int getSaddleHeight() {
return saddleHeight;
}
public void setSaddleHeight(int saddleHeight) {
this.saddleHeight = saddleHeight;
}
}
Modified text is an extract of the original Stack Overflow Documentation
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