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package com.stackoverflow.jaizen;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
@Entity
public class A {
@Id
private int id;
private String name;
@ManyToOne
@Column(name = "manager_id")
private B manager;
@ManyToOne
@Column(name = "supervisor_id")
private B supervisor;
@ManyToOne
@Column(name = "worker_id")
private B worker;
public A(int id, String name) {
this.id = id;
this.name = name;
}
protected A() {}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public B getManager() {
return manager;
}
public void setManager(B manager) {
this.manager = manager;
}
public B getSupervisor() {
return supervisor;
}
public void setSupervisor(B supervisor) {
this.supervisor = supervisor;
}
public B getWorker() {
return worker;
}
public void setWorker(B worker) {
this.worker = worker;
}
public int getId() {
return id;
}
@Override
public int hashCode() {
return id;
}
@Override
public boolean equals(Object that) {
return (this == that) || ((that instanceof A) && (this.id == ((A) that).id));
}
@Override
public String toString() {
return "A [id=" + id + ", name=" + name + ", manager=" + manager + ", supervisor=" + supervisor + ", worker=" + worker + "]";
}
}
package com.stackoverflow.jaizen;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class B {
@Id
private int id;
private String name;
public B(int id, String name) {
this.id = id;
this.name = name;
}
protected B() {}
public int getId() {
return id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public int hashCode() {
return id;
}
@Override
public boolean equals(Object that) {
return (this == that) || ((that instanceof B) && (this.id == ((B) that).id));
}
@Override
public String toString() {
return "B [id=" + id + ", name=" + name + "]";
}
}
package com.stackoverflow.jaizen;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class JaizenQuestion {
private static final int CARMEN_ID = 300;
private static final int BOB_ID = 200;
private static final int ALICE_ID = 100;
private static final int JOB_ID = 9000;
public static void main(String[] args) {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("sandbox");
setup(emf);
change(emf);
System.out.println("------------------------------------------------------------------------------------------");
query(emf);
emf.close();
}
private static void setup(EntityManagerFactory emf) {
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
B alice = em.merge(new B(ALICE_ID, "Alice"));
B bob = em.merge(new B(BOB_ID, "Bob"));
B carmen = em.merge(new B(CARMEN_ID, "Carmen"));
System.out.println(alice);
System.out.println(bob);
System.out.println(carmen);
A job = em.merge(new A(JOB_ID, "The Job"));
job.setManager(alice);
job.setSupervisor(alice);
job.setWorker(alice);
System.out.println(job);
em.getTransaction().commit();
em.close();
}
private static void change(EntityManagerFactory emf) {
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
A job = em.find(A.class, JOB_ID);
B bob = em.find(B.class, BOB_ID);
B carmen = em.find(B.class, CARMEN_ID);
job.setSupervisor(bob);
job.setWorker(carmen);
em.getTransaction().commit();
em.close();
}
private static void query(EntityManagerFactory emf) {
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
B alice = em.find(B.class, ALICE_ID);
B bob = em.find(B.class, BOB_ID);
B carmen = em.find(B.class, CARMEN_ID);
System.out.println(alice);
System.out.println(bob);
System.out.println(carmen);
A job = em.find(A.class, JOB_ID);
System.out.println(job);
em.getTransaction().commit();
em.close();
}
}
B [id=100, name=Alice]
B [id=200, name=Bob]
B [id=300, name=Carmen]
A [id=9000, name=The Job, manager=B [id=100, name=Alice], supervisor=B [id=100, name=Alice], worker=B [id=100, name=Alice]]
------------------------------------------------------------------------------------------
B [id=100, name=Alice]
B [id=200, name=Bob]
B [id=300, name=Carmen]
A [id=9000, name=The Job, manager=B [id=100, name=Alice], supervisor=B [id=200, name=Bob], worker=B [id=300, name=Carmen]]
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