JPA Entities and the Serializable Interface

persistence-modules/hibernate-jpa/src/main/java/com/baeldung/hibernate/serializable/Account.java

@@ -0,0 +1,41 @@
+package com.baeldung.hibernate.serializable;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+
+@Entity
+public class Account {
+
+    @Id
+    private long id;
+    private String type;
+    @ManyToOne
+    @JoinColumn(referencedColumnName = "email")
+    private User user;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public User getUser() {
+        return user;
+    }
+
+    public void setUser(User user) {
+        this.user = user;
+    }
+}

persistence-modules/hibernate-jpa/src/main/java/com/baeldung/hibernate/serializable/Email.java

@@ -0,0 +1,38 @@
+package com.baeldung.hibernate.serializable;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import java.io.Serializable;
+
+@Entity
+public class Email implements Serializable {
+
+    @Id
+    private long id;
+    private String name;
+    private String domain;
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getDomain() {
+        return domain;
+    }
+
+    public void setDomain(String domain) {
+        this.domain = domain;
+    }
+}

persistence-modules/hibernate-jpa/src/main/java/com/baeldung/hibernate/serializable/User.java

@@ -0,0 +1,36 @@
+package com.baeldung.hibernate.serializable;
+
+import javax.persistence.EmbeddedId;
+import javax.persistence.Entity;
+
+@Entity
+public class User {
+
+    @EmbeddedId private UserId userId;
+    private Email email;
+
+
+    public User() {
+    }
+
+    public User(UserId userId, Email email) {
+        this.userId = userId;
+        this.email = email;
+    }
+
+    public UserId getUserId() {
+        return userId;
+    }
+
+    public void setUserId(UserId userId) {
+        this.userId = userId;
+    }
+
+    public Email getEmail() {
+        return email;
+    }
+
+    public void setEmail(Email email) {
+        this.email = email;
+    }
+}

persistence-modules/hibernate-jpa/src/main/java/com/baeldung/hibernate/serializable/UserId.java

@@ -0,0 +1,27 @@
+package com.baeldung.hibernate.serializable;
+
+import javax.persistence.Embeddable;
+import java.io.Serializable;
+
+@Embeddable
+public class UserId implements Serializable {
+
+    private String name;
+    private String lastName;
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+}

persistence-modules/hibernate-jpa/src/main/resources/META-INF/persistence.xml

@@ -100,4 +100,23 @@
 
         </properties>
     </persistence-unit>
+
+    <persistence-unit name="com.baeldung.hibernate.serializable.h2_persistence_unit">
+        <description>EntityManager serializable persistence unit</description>
+        <class>com.baeldung.hibernate.serializable.Email</class>
+        <class>com.baeldung.hibernate.serializable.Account</class>
+        <class>com.baeldung.hibernate.serializable.User</class>
+        <class>com.baeldung.hibernate.serializable.UserId</class>
+        <exclude-unlisted-classes>true</exclude-unlisted-classes>
+        <properties>
+            <property name="hibernate.hbm2ddl.auto" value="update"/>
+            <property name="hibernate.show_sql" value="true"/>
+            <property name="hibernate.generate_statistics" value="false"/>
+            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
+            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
+            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:db1;DB_CLOSE_DELAY=-1"/>
+            <property name="javax.persistence.jdbc.user" value="sa"/>
+            <property name="javax.persistence.jdbc.password" value=""/>
+        </properties>
+    </persistence-unit>
 </persistence> 

persistence-modules/hibernate-jpa/src/test/java/com/baeldung/hibernate/serializable/JPASerializableIntegrationTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.hibernate.serializable;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.Persistence;
+import java.io.IOException;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class JPASerializableIntegrationTest {
+
+    private static EntityManager entityManager;
+
+    @Before
+    public void setUp() throws IOException {
+        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("com.baeldung.hibernate.serializable.h2_persistence_unit");
+        entityManager = entityManagerFactory.createEntityManager();
+        entityManager.getTransaction().begin();
+    }
+
+    @Test
+    public void givenUser_whenPersisted_thenUserWillBeFoundById() {
+        UserId userId = new UserId();
+        userId.setName("John");
+        userId.setLastName("Doe");
+        Email email = new Email();
+        email.setId(1);
+        email.setName("johndoe");
+        email.setDomain("gmail.com");
+        User user = new User(userId, email);
+
+        entityManager.persist(user);
+
+        User userDb = entityManager.find(User.class, userId);
+        assertEquals(userDb.getEmail().getName(), "johndoe");
+    }
+
+@Test
+public void givenAssociation_whenPersisted_thenMultipleAccountsWillBeFoundByEmail() {
+    UserId userId = new UserId();
+    userId.setName("John");
+    userId.setLastName("Doe");
+    Email email = new Email();
+    email.setId(1);
+    email.setName("johndoe");
+    email.setDomain("gmail.com");
+    User user = new User(userId, email);
+    Account account = new Account();
+    account.setType("test");
+    account.setId(10);
+    account.setUser(user);
+    Account account2 = new Account();
+    account2.setType("main");
+    account2.setId(11);
+    account2.setUser(user);
+
+    entityManager.persist(user);
+    entityManager.persist(account);
+    entityManager.persist(account2);
+
+    List userAccounts = entityManager.createQuery("select a from Account a join fetch a.user where a.user.email = :email")
+            .setParameter("email", email).getResultList();
+    assertEquals(userAccounts.size(), 2);
+}
+
+    @After
+    public void tearDown() {
+        entityManager.close();
+    }
+
+}