Java JPA FetchType.EAGER不工作
我正在用javaee(Jersey)和JPA制作一个应用程序,其中我遇到了未初始化实体的问题。我有三个实体:汽车、车主、房子,其中汽车可以有多个车主,车主可以有多个房子。当我返回(entityManager.find)汽车时,车主被初始化。当我返回房屋时,所有者已初始化,但汽车未初始化。我希望能够调用House.getOwner().getCar().getId()之类的东西。现在我必须给房子打电话,然后给车主打电话去弄车。我如何解决这个问题Java JPA FetchType.EAGER不工作,java,jpa,jersey,fetch,Java,Jpa,Jersey,Fetch,我正在用javaee(Jersey)和JPA制作一个应用程序,其中我遇到了未初始化实体的问题。我有三个实体:汽车、车主、房子,其中汽车可以有多个车主,车主可以有多个房子。当我返回(entityManager.find)汽车时,车主被初始化。当我返回房屋时,所有者已初始化,但汽车未初始化。我希望能够调用House.getOwner().getCar().getId()之类的东西。现在我必须给房子打电话,然后给车主打电话去弄车。我如何解决这个问题 @Entity @Table(name = "Hou
@Entity
@Table(name = "House")
public class HouseEntity {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "owner_id", nullable = false)
private OwnerEntity owner;
}
@Entity
@Table(name = "Owner")
public class OwnerEntity {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "car_id")
private CarEntity car;
@OneToMany(mappedBy = "owner")
@JoinColumn(name = "house", nullable = false)
private Set<HouseEntity> house;
}
@Entity
@Table(name = "Car")
public class CarEntity {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@OneToMany(mappedBy = "owner")
private Set<OwnerEntity> owner;
}
@实体
@表(name=“House”)
公共类房屋实体{
@身份证
@列(name=“id”)
@GeneratedValue(策略=GenerationType.IDENTITY)
私人长id;
@manytone(fetch=FetchType.EAGER)
@JoinColumn(name=“owner\u id”,nullable=false)
私人所有者;
}
@实体
@表(name=“Owner”)
公共阶级所有权{
@身份证
@列(name=“id”)
@GeneratedValue(策略=GenerationType.IDENTITY)
私人长id;
@manytone(fetch=FetchType.EAGER)
@JoinColumn(name=“car\u id”)
私家车;
@OneToMany(mappedBy=“所有者”)
@JoinColumn(name=“house”,nullable=false)
私人住宅;
}
@实体
@表(name=“Car”)
公共阶级关怀{
@身份证
@列(name=“id”)
@GeneratedValue(策略=GenerationType.IDENTITY)
私人长id;
@OneToMany(mappedBy=“所有者”)
私人设置所有者;
}
Edit1:很抱歉,在映射中出现了错误,类运行良好。但初始化问题仍然存在。尝试以下操作:
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Entity
@Table(name = "House")
public class HouseEntity {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToOne
@JoinColumn(name = "owner_id", nullable = false)
private OwnerEntity owner;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public OwnerEntity getOwner() {
return owner;
}
public void setOwner(OwnerEntity owner) {
this.owner = owner;
}
}
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;
@Entity
@Table(name = "Owner")
public class OwnerEntity {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@ManyToOne
@JoinColumn(name = "car_id")
private CarEntity car;
@OneToMany(mappedBy = "owner", fetch = FetchType.EAGER)
private Set<HouseEntity> houses;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public CarEntity getCar() {
return car;
}
public void setCar(CarEntity car) {
this.car = car;
}
public Set<HouseEntity> getHouses() {
return houses;
}
public void setHouses(Set<HouseEntity> houses) {
this.houses = houses;
}
}
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
@Entity
@Table(name = "Car")
public class CarEntity {
@Id
@Column(name = "id")
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@OneToMany(mappedBy = "car", fetch = FetchType.EAGER)
private Set<OwnerEntity> owner;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public Set<OwnerEntity> getOwner() {
return owner;
}
public void setOwner(Set<OwnerEntity> owner) {
this.owner = owner;
}
public void addOwner(OwnerEntity owner){
this.owner.add(owner);
}
}
import javax.persistence.Column;
导入javax.persistence.Entity;
导入javax.persistence.GeneratedValue;
导入javax.persistence.GenerationType;
导入javax.persistence.Id;
导入javax.persistence.JoinColumn;
导入javax.persistence.manytone;
导入javax.persistence.Table;
@实体
@表(name=“House”)
公共类房屋实体{
@身份证
@列(name=“id”)
@GeneratedValue(策略=GenerationType.AUTO)
私人长id;
@许多酮
@JoinColumn(name=“owner\u id”,nullable=false)
私人所有者;
公共长getId(){
返回id;
}
公共无效集合id(长id){
this.id=id;
}
public OwnerEntity getOwner(){
归还所有人;
}
public void setOwner(OwnerEntity所有者){
this.owner=所有者;
}
}
导入java.util.Set;
导入javax.persistence.Column;
导入javax.persistence.Entity;
导入javax.persistence.FetchType;
导入javax.persistence.GeneratedValue;
导入javax.persistence.GenerationType;
导入javax.persistence.Id;
导入javax.persistence.JoinColumn;
导入javax.persistence.manytone;
导入javax.persistence.OneToMany;
导入javax.persistence.Table;
@实体
@表(name=“Owner”)
公共阶级所有权{
@身份证
@列(name=“id”)
@GeneratedValue(策略=GenerationType.AUTO)
私人长id;
@许多酮
@JoinColumn(name=“car\u id”)
私家车;
@OneToMany(mappedBy=“owner”,fetch=FetchType.EAGER)
私人住宅;
公共长getId(){
返回id;
}
公共无效集合id(长id){
this.id=id;
}
公共事业{
返回车;
}
公共车辆(CarEntity car){
这辆车;
}
公共设施{
归还房屋;
}
公共休息室(休息室){
这个房子=房子;
}
}
导入java.util.Set;
导入javax.persistence.Column;
导入javax.persistence.Entity;
导入javax.persistence.FetchType;
导入javax.persistence.GeneratedValue;
导入javax.persistence.GenerationType;
导入javax.persistence.Id;
导入javax.persistence.OneToMany;
导入javax.persistence.Table;
@实体
@表(name=“Car”)
公共阶级关怀{
@身份证
@列(name=“id”)
@GeneratedValue(策略=GenerationType.AUTO)
私人长id;
@OneToMany(mappedBy=“car”,fetch=FetchType.EAGER)
私人设置所有者;
公共长getId(){
返回id;
}
公共无效集合id(长id){
this.id=id;
}
公共集getOwner(){
归还所有人;
}
公共无效集合所有者(集合所有者){
this.owner=所有者;
}
public void addOwner(OwnerEntity所有者){
this.owner.add(owner);
}
}
当您获取汽车时,将填充整个对象图。尝试使用Hibernate.initialize()此处出现错误:OwnerEntity将自身映射为Set owner?是的,我在那里犯了个错误。我认为这些实体很大,所以我将它们编辑得更短,但出现了错误。注意,所有者mappedBy也错了,应该是mappedBy=“car”,除了打字错误会阻止hibernate映射实体,我认为映射中没有问题。问题在别处,您是否检查了getter和setter方法名称是否与属性名称匹配?区别是什么?请补充一些解释。