Proxy in Hibernate load() method (#5222)

hibernate5/src/main/java/com/baeldung/hibernate/proxy/BatchEmployee.java

@@ -0,0 +1,56 @@
+package com.baeldung.hibernate.proxy;
+
+import org.hibernate.annotations.BatchSize;
+
+import javax.persistence.*;
+import java.io.Serializable;
+
+@Entity
+@BatchSize(size = 5)
+public class BatchEmployee implements Serializable {
+
+    @Id
+    @GeneratedValue (strategy = GenerationType.SEQUENCE)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    private Boss boss;
+
+    @Column(name = "name")
+    private String name;
+
+    @Column(name = "surname")
+    private String surname;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Boss getBoss() {
+        return boss;
+    }
+
+    public void setBoss(Boss boss) {
+        this.boss = boss;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getSurname() {
+        return surname;
+    }
+
+    public void setSurname(String surname) {
+        this.surname = surname;
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/proxy/Boss.java

@@ -0,0 +1,49 @@
+package com.baeldung.hibernate.proxy;
+
+import javax.persistence.*;
+import java.io.Serializable;
+
+@Entity
+public class Boss implements Serializable {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
+    private Long id;
+
+    @Column(name = "name")
+    private String name;
+
+    @Column(name = "surname")
+    private String surname;
+
+    public Boss() { }
+
+    public Boss(String name, String surname) {
+        this.name = name;
+        this.surname = surname;
+    }
+
+    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 getSurname() {
+        return surname;
+    }
+
+    public void setSurname(String surname) {
+        this.surname = surname;
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/proxy/Employee.java

@@ -0,0 +1,53 @@
+package com.baeldung.hibernate.proxy;
+
+import javax.persistence.*;
+import java.io.Serializable;
+
+@Entity
+public class Employee implements Serializable {
+
+    @Id
+    @GeneratedValue (strategy = GenerationType.SEQUENCE)
+    private Long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    private Boss boss;
+
+    @Column(name = "name")
+    private String name;
+
+    @Column(name = "surname")
+    private String surname;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public Boss getBoss() {
+        return boss;
+    }
+
+    public void setBoss(Boss boss) {
+        this.boss = boss;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getSurname() {
+        return surname;
+    }
+
+    public void setSurname(String surname) {
+        this.surname = surname;
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/proxy/HibernateUtil.java

@@ -0,0 +1,57 @@
+package com.baeldung.hibernate.proxy;
+
+import org.apache.commons.lang3.StringUtils;
+import org.hibernate.SessionFactory;
+import org.hibernate.boot.Metadata;
+import org.hibernate.boot.MetadataSources;
+import org.hibernate.boot.SessionFactoryBuilder;
+import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.service.ServiceRegistry;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.net.URL;
+import java.util.Properties;
+
+public class HibernateUtil {
+
+    private static SessionFactory sessionFactory;
+    private static String PROPERTY_FILE_NAME;
+
+    public static SessionFactory getSessionFactory(String propertyFileName) throws IOException {
+        PROPERTY_FILE_NAME = propertyFileName;
+        if (sessionFactory == null) {
+            ServiceRegistry serviceRegistry = configureServiceRegistry();
+            sessionFactory = getSessionFactoryBuilder(serviceRegistry).build();
+        }
+        return sessionFactory;
+    }
+
+    private static SessionFactoryBuilder getSessionFactoryBuilder(ServiceRegistry serviceRegistry) {
+        MetadataSources metadataSources = new MetadataSources(serviceRegistry);
+        metadataSources.addPackage("com.baeldung.hibernate.proxy");
+        metadataSources.addAnnotatedClass(Boss.class);
+        metadataSources.addAnnotatedClass(Employee.class);
+
+        Metadata metadata = metadataSources.buildMetadata();
+        return metadata.getSessionFactoryBuilder();
+
+    }
+
+    private static ServiceRegistry configureServiceRegistry() throws IOException {
+        Properties properties = getProperties();
+        return new StandardServiceRegistryBuilder().applySettings(properties)
+            .build();
+    }
+
+    private static Properties getProperties() throws IOException {
+        Properties properties = new Properties();
+        URL propertiesURL = Thread.currentThread()
+            .getContextClassLoader()
+            .getResource(StringUtils.defaultString(PROPERTY_FILE_NAME, "hibernate.properties"));
+        try (FileInputStream inputStream = new FileInputStream(propertiesURL.getFile())) {
+            properties.load(inputStream);
+        }
+        return properties;
+    }
+}

hibernate5/src/test/java/com/baeldung/hibernate/proxy/HibernateProxyUnitTest.java

@@ -0,0 +1,75 @@
+package com.baeldung.hibernate.proxy;
+
+import org.hibernate.*;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+import java.util.List;
+
+import static org.junit.Assert.fail;
+
+public class HibernateProxyUnitTest {
+
+    private Session session;
+
+    @Before
+    public void init(){
+        try {
+            session = HibernateUtil.getSessionFactory("hibernate.properties")
+                    .openSession();
+        } catch (HibernateException | IOException e) {
+            fail("Failed to initiate Hibernate Session [Exception:" + e.toString() + "]");
+        }
+
+        Boss boss = new Boss("Eduard", "Freud");
+        session.save(boss);
+    }
+
+    @After
+    public void close(){
+        if(session != null) {
+            session.close();
+        }
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void givenAnInexistentEmployeeId_whenUseGetMethod_thenReturnNull() {
+        Employee employee = session.get(Employee.class, new Long(14));
+        assertNull(employee);
+        employee.getId();
+    }
+
+    @Test
+    public void givenAnInexistentEmployeeId_whenUseLoadMethod_thenReturnAProxy() {
+        Employee employee = session.load(Employee.class, new Long(14));
+        assertNotNull(employee);
+    }
+
+    @Test
+    public void givenABatchEmployeeList_whenSaveOne_thenSaveTheWholeBatch() {
+        Transaction transaction = session.beginTransaction();
+
+        for (long i = 1; i <= 5; i++) {
+            Employee employee = new Employee();
+            employee.setName("Employee " + i);
+            session.save(employee);
+        }
+
+        //After this line is possible to see all the insertions in the logs
+        session.flush();
+        session.clear();
+        transaction.commit();
+
+        transaction = session.beginTransaction();
+
+        List<Employee> employeeList = session.createQuery("from Employee")
+                                        .setCacheMode(CacheMode.IGNORE).getResultList();
+
+        assertEquals(employeeList.size(), 5);
+        transaction.commit();
+    }
+}