Welcome to the Hibernate tutorial for Beginners. Hibernate is one of the most widely used Java ORM tool. Most of the applications use relational databases to store application information and at the low level we use JDBC API for connecting to databases and perform CRUD operations.
Hibernate Tutorial for Beginners
If you look at the JDBC code, there is so much of boiler plate code and there are chances of resource leak and data inconsistency because all the work needs to be done by the developer. This is where an ORM tool comes handy.
Object-relational mapping or ORM is the programming technique to map application domain model objects to the relational database tables. Hibernate is java based ORM tool that provides framework for mapping application domain objects to the relational database tables and vice versa.
Some of the benefits of using Hibernate as ORM tool are:
- Hibernate supports mapping of java classes to database tables and vice versa. It provides features to perform CRUD operations across all the major relational databases.
- Hibernate eliminates all the boiler-plate code that comes with JDBC and takes care of managing resources, so we can focus on business use cases rather than making sure that database operations are not causing resource leaks.
- Hibernate supports transaction management and make sure there is no inconsistent data present in the system.
- Since we use XML, property files or annotations for mapping java classes to database tables, it provides an abstraction layer between application and database.
- Hibernate helps us in mapping joins, collections, inheritance objects and we can easily visualize how our model classes are representing database tables.
- Hibernate provides a powerful query language (HQL) that is similar to SQL. However, HQL is fully object-oriented and understands concepts like inheritance, polymorphism and association.
- Hibernate also offers integration with some external modules. For example Hibernate Validator is the reference implementation of Bean Validation (JSR 303).
- Hibernate is an open source project from Red Hat Community and used worldwide. This makes it a better choice than others because learning curve is small and there are tons of online documentations and help is easily available in forums.
- Hibernate is easy to integrate with other Java EE frameworks, it’s so popular that Spring Framework provides built-in support for integrating hibernate with Spring applications.
I hope all the above benefits will convince you that Hibernate is the best choice for your application object-relational mapping requirements. Let’s look at the Hibernate Framework architecture now and then we will jump into sample project where we will look into different ways to configure Hibernate in standalone java application and use it.
Hibernate Architecture
Below image shows the Hibernate architecture and how it works as an abstraction layer between application classes and JDBC/JTA APIs for database operations. It’s clear that Hibernate is built on top of JDBC and JTA APIs.
Let’s look at the core components of hibernate architecture one by one.
- SessionFactory (org.hibernate.SessionFactory): SessionFactory is an immutable thread-safe cache of compiled mappings for a single database. We can get instance of
org.hibernate.SessionusingSessionFactory. - Session (org.hibernate.Session): Session is a single-threaded, short-lived object representing a conversation between the application and the persistent store. It wraps JDBC
java.sql.Connectionand works as a factory fororg.hibernate.Transaction. - Persistent objects: Persistent objects are short-lived, single threaded objects that contains persistent state and business function. These can be ordinary JavaBeans/POJOs. They are associated with exactly one
org.hibernate.Session. - Transient objects: Transient objects are persistent classes instances that are not currently associated with a
org.hibernate.Session. They may have been instantiated by the application and not yet persisted, or they may have been instantiated by a closedorg.hibernate.Session. - Transaction (org.hibernate.Transaction): Transaction is a single-threaded, short-lived object used by the application to specify atomic units of work. It abstracts the application from the underlying JDBC or JTA transaction. A
org.hibernate.Sessionmight span multipleorg.hibernate.Transactionin some cases. - ConnectionProvider (org.hibernate.connection.ConnectionProvider): ConnectionProvider is a factory for JDBC connections. It provides abstraction between the application and underlying
javax.sql.DataSourceorjava.sql.DriverManager. It is not exposed to application, but it can be extended by the developer. - TransactionFactory (org.hibernate.TransactionFactory): A factory for
org.hibernate.Transactioninstances.
Hibernate and Java Persistence API (JPA)
Hibernate provides implementation of Java Persistence API, so we can use JPA annotations with model beans and hibernate will take care of configuring it to be used in CRUD operations. We will look into this with annotations example.
Hibernate Example
When developing hibernate applications, we need to provide two set of configuration. First set of configuration contains database specific properties that will be used to create Database connection and Session objects. Second set of configurations contains mapping between model classes and database tables.
We can use XML based or properties based configuration for database connection related configurations. We can use XML based or annotation based configurations for providing model classes and database tables mapping. We will use JPA annotations from javax.persistence for annotation based mappings.
Our final project will look like below image.
Create a Maven project in Eclipse or your favorite IDE, you can keep any name of your choice. Before we move on to the different components of the project, we will have to do the database setup.
Database Table Setup
For my example, I am using MySQL database and below script is used to create necessary table.
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CREATE TABLE `Employee` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(20) DEFAULT NULL, `role` varchar(20) DEFAULT NULL, `insert_time` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=19 DEFAULT CHARSET=utf8; |
Notice that Employee table “id” column is automatically generated by MySQL, so we don’t need to insert it.
Hibernate Project Dependencies
Our final pom.xml file looks like below.
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<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.journaldev.hibernate</groupId> <artifactId>HibernateExample</artifactId> <version>0.0.1-SNAPSHOT</version> <name>HibernateExample</name> <dependencies> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>4.3.5.Final</version> </dependency> <!-- Hibernate 4 uses Jboss logging, but older versions slf4j for logging --> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-simple</artifactId> <version>1.7.5</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.0.5</version> </dependency> </dependencies> <build> <finalName>${project.artifactId}</finalName> </build> </project> |
hibernate-core artifact contains all the core hibernate classes, so we will get all the necessary features by including it in the project.
Note that I am using latest Hibernate version (4.3.5.Final) for my sample project and Hibernate is still evolving and I have seen that a lot of core classes change between every major release. So if you are using any other version, there is a small chance that you will have to modify the Hibernate configurations for it to work. However, I am sure that it will work fine for all the 4.x.x releases.
Hibernate 4 uses JBoss logging but older versions uses slf4j for logging purposes, so I have included slf4j-simple artifact in my project, although not needed because I am using Hibernate 4.
mysql-connector-java is the MySQL driver for connecting to MySQL databases, if you are using any other database then add corresponding driver artifact.
Domain Model Classes
As you can see in above image that we have two model classes, Employee and Employee1.
Employee is a simple Java Bean class and we will use XML based configuration for providing it’s mapping details.
Employee1 is a java bean where fields are annotated with JPA annotations, so that we don’t need to provide mapping in separate XML file.
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package com.journaldev.hibernate.model; import java.util.Date; public class Employee { private int id; private String name; private String role; private Date insertTime; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getRole() { return role; } public void setRole(String role) { this.role = role; } public Date getInsertTime() { return insertTime; } public void setInsertTime(Date insertTime) { this.insertTime = insertTime; } } |
Employee class is simple java bean, there is nothing specific to discuss here.
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package com.journaldev.hibernate.model; import java.util.Date; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import javax.persistence.UniqueConstraint; @Entity @Table(name="Employee", uniqueConstraints={@UniqueConstraint(columnNames={"ID"})}) public class Employee1 { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) @Column(name="ID", nullable=false, unique=true, length=11) private int id; @Column(name="NAME", length=20, nullable=true) private String name; @Column(name="ROLE", length=20, nullable=true) private String role; @Column(name="insert_time", nullable=true) private Date insertTime; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getRole() { return role; } public void setRole(String role) { this.role = role; } public Date getInsertTime() { return insertTime; } public void setInsertTime(Date insertTime) { this.insertTime = insertTime; } } |
javax.persistence.Entity annotation is used to mark a class as Entity bean that can be persisted by hibernate, since hibernate provides JPA implementation.
javax.persistence.Table annotation is used to define the table mapping and unique constraints for the columns.
javax.persistence.Id annotation is used to define the primary key for the table. javax.persistence.GeneratedValue is used to define that the field will be auto generated and GenerationType.IDENTITY strategy is used so that the generated “id” value is mapped to the bean and can be retrieved in the java program.
javax.persistence.Column is used to map the field with table column, we can also specify length, nullable and uniqueness for the bean properties.
Hibernate Mapping XML Configuration
As stated above, we will use XML based configuration for Employee class mapping. We can choose any name, but it’s good to choose with table or java bean name for clarity. Our hibernate mapping file for Employee bean looks like below.
employee.hbm.xml
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<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "https://hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="com.journaldev.hibernate.model.Employee" table="EMPLOYEE"> <id name="id" type="int"> <column name="ID" /> <generator class="increment" /> </id> <property name="name" type="java.lang.String"> <column name="NAME" /> </property> <property name="role" type="java.lang.String"> <column name="ROLE" /> </property> <property name="insertTime" type="timestamp"> <column name="insert_time" /> </property> </class> </hibernate-mapping> |
The xml configuration is simple and does the same thing as annotation based configuration.
Hibernate Configuration Files
We will create two hibernate configuration xml files – one for xml based configuration and another for annotation based configuration.
hibernate.cfg.xml
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "https://hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- Database connection properties - Driver, URL, user, password --> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost/TestDB</property> <property name="hibernate.connection.username">pankaj</property> <property name="hibernate.connection.password">pankaj123</property> <!-- Connection Pool Size --> <property name="hibernate.connection.pool_size">1</property> <!-- org.hibernate.HibernateException: No CurrentSessionContext configured! --> <property name="hibernate.current_session_context_class">thread</property> <!-- Outputs the SQL queries, should be disabled in Production --> <property name="hibernate.show_sql">true</property> <!-- Dialect is required to let Hibernate know the Database Type, MySQL, Oracle etc Hibernate 4 automatically figure out Dialect from Database Connection Metadata --> <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> <!-- mapping file, we can use Bean annotations too --> <mapping resource="employee.hbm.xml" /> </session-factory> </hibernate-configuration> |
Most of the properties are related to database configurations, other properties details are given in comment. Note the configuration for hibernate mapping file, we can define multiple hibernate mapping files and configure them here. Also note that mapping is specific to session factory.
hibernate-annotation.cfg.xml
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "https://hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <!-- Database connection properties - Driver, URL, user, password --> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost/TestDB</property> <property name="hibernate.connection.username">pankaj</property> <property name="hibernate.connection.password">pankaj123</property> <!-- org.hibernate.HibernateException: No CurrentSessionContext configured! --> <property name="hibernate.current_session_context_class">thread</property> <!-- Mapping with model class containing annotations --> <mapping class="com.journaldev.hibernate.model.Employee1"/> </session-factory> </hibernate-configuration> |
Most of the configuration is same as XML based configuration, the only difference is the mapping configuration. We can provide mapping configuration for classes as well as packages.
Hibernate SessionFactory
I have created a utility class where I am creating SessionFactory from XML based configuration as well as property based configuration. For property based configuration, we could have a property file and read it in the class, but for simplicity I am creating Properties instance in the class itself.
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package com.journaldev.hibernate.util; import java.util.Properties; import org.hibernate.SessionFactory; import org.hibernate.boot.registry.StandardServiceRegistryBuilder; import org.hibernate.cfg.Configuration; import org.hibernate.service.ServiceRegistry; import com.journaldev.hibernate.model.Employee1; public class HibernateUtil { //XML based configuration private static SessionFactory sessionFactory; //Annotation based configuration private static SessionFactory sessionAnnotationFactory; //Property based configuration private static SessionFactory sessionJavaConfigFactory; private static SessionFactory buildSessionFactory() { try { // Create the SessionFactory from hibernate.cfg.xml Configuration configuration = new Configuration(); configuration.configure("hibernate.cfg.xml"); System.out.println("Hibernate Configuration loaded"); ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build(); System.out.println("Hibernate serviceRegistry created"); SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry); return sessionFactory; } catch (Throwable ex) { // Make sure you log the exception, as it might be swallowed System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } private static SessionFactory buildSessionAnnotationFactory() { try { // Create the SessionFactory from hibernate.cfg.xml Configuration configuration = new Configuration(); configuration.configure("hibernate-annotation.cfg.xml"); System.out.println("Hibernate Annotation Configuration loaded"); ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build(); System.out.println("Hibernate Annotation serviceRegistry created"); SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry); return sessionFactory; } catch (Throwable ex) { // Make sure you log the exception, as it might be swallowed System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } private static SessionFactory buildSessionJavaConfigFactory() { try { Configuration configuration = new Configuration(); //Create Properties, can be read from property files too Properties props = new Properties(); props.put("hibernate.connection.driver_class", "com.mysql.jdbc.Driver"); props.put("hibernate.connection.url", "jdbc:mysql://localhost/TestDB"); props.put("hibernate.connection.username", "pankaj"); props.put("hibernate.connection.password", "pankaj123"); props.put("hibernate.current_session_context_class", "thread"); configuration.setProperties(props); //we can set mapping file or class with annotation //addClass(Employee1.class) will look for resource // com/journaldev/hibernate/model/Employee1.hbm.xml (not good) configuration.addAnnotatedClass(Employee1.class); ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build(); System.out.println("Hibernate Java Config serviceRegistry created"); SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry); return sessionFactory; } catch (Throwable ex) { System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { if(sessionFactory == null) sessionFactory = buildSessionFactory(); return sessionFactory; } public static SessionFactory getSessionAnnotationFactory() { if(sessionAnnotationFactory == null) sessionAnnotationFactory = buildSessionAnnotationFactory(); return sessionAnnotationFactory; } public static SessionFactory getSessionJavaConfigFactory() { if(sessionJavaConfigFactory == null) sessionJavaConfigFactory = buildSessionJavaConfigFactory(); return sessionJavaConfigFactory; } } |
Creating SessionFactory for XML based configuration is same whether mapping is XML based or annotation based. For properties based, we need to set the properties in Configuration object and add annotation classes before creating the SessionFactory.
Overall creating SessionFactory includes following steps:
- Creating
Configurationobject and configure it - Creating
ServiceRegistryobject and apply configuration settings. - Use
configuration.buildSessionFactory()by passingServiceRegistryobject as argument to get theSessionFactoryobject.
Our application is almost ready now, let’s write some test programs and execute them.
Hibernate XML Configuration Test
Our test program looks like below.
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package com.journaldev.hibernate.main; import java.util.Date; import org.hibernate.Session; import com.journaldev.hibernate.model.Employee; import com.journaldev.hibernate.util.HibernateUtil; public class HibernateMain { public static void main(String[] args) { Employee emp = new Employee(); emp.setName("Pankaj"); emp.setRole("CEO"); emp.setInsertTime(new Date()); //Get Session Session session = HibernateUtil.getSessionFactory().getCurrentSession(); //start transaction session.beginTransaction(); //Save the Model object session.save(emp); //Commit transaction session.getTransaction().commit(); System.out.println("Employee ID="+emp.getId()); //terminate session factory, otherwise program won't end HibernateUtil.getSessionFactory().close(); } } |
The program is self understood, when we execute the test program, we get following output.
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May 06, 2014 12:40:06 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit> INFO: HCANN000001: Hibernate Commons Annotations {4.0.4.Final} May 06, 2014 12:40:06 AM org.hibernate.Version logVersion INFO: HHH000412: Hibernate Core {4.3.5.Final} May 06, 2014 12:40:06 AM org.hibernate.cfg.Environment <clinit> INFO: HHH000206: hibernate.properties not found May 06, 2014 12:40:06 AM org.hibernate.cfg.Environment buildBytecodeProvider INFO: HHH000021: Bytecode provider name : javassist May 06, 2014 12:40:06 AM org.hibernate.cfg.Configuration configure INFO: HHH000043: Configuring from resource: hibernate.cfg.xml May 06, 2014 12:40:06 AM org.hibernate.cfg.Configuration getConfigurationInputStream INFO: HHH000040: Configuration resource: hibernate.cfg.xml May 06, 2014 12:40:07 AM org.hibernate.cfg.Configuration addResource INFO: HHH000221: Reading mappings from resource: employee.hbm.xml May 06, 2014 12:40:08 AM org.hibernate.cfg.Configuration doConfigure INFO: HHH000041: Configured SessionFactory: null Hibernate Configuration loaded Hibernate serviceRegistry created May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!) May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://localhost/TestDB] May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000046: Connection properties: {user=pankaj, password=****} May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000006: Autocommit mode: false May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000115: Hibernate connection pool size: 1 (min=1) May 06, 2014 12:40:08 AM org.hibernate.dialect.Dialect <init> INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQLDialect May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.internal.LobCreatorBuilder useContextualLobCreation INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 May 06, 2014 12:40:08 AM org.hibernate.engine.transaction.internal.TransactionFactoryInitiator initiateService INFO: HHH000399: Using default transaction strategy (direct JDBC transactions) May 06, 2014 12:40:08 AM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init> INFO: HHH000397: Using ASTQueryTranslatorFactory Hibernate: select max(ID) from EMPLOYEE Hibernate: insert into EMPLOYEE (NAME, ROLE, insert_time, ID) values (?, ?, ?, ?) Employee ID=19 May 06, 2014 12:40:08 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop INFO: HHH000030: Cleaning up connection pool [jdbc:mysql://localhost/TestDB] |
Notice that it’s printing the generated employee id, you can check database table to confirm it.
Hibernate Annotation Configuration Test
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package com.journaldev.hibernate.main; import java.util.Date; import org.hibernate.Session; import org.hibernate.SessionFactory; import com.journaldev.hibernate.model.Employee1; import com.journaldev.hibernate.util.HibernateUtil; public class HibernateAnnotationMain { public static void main(String[] args) { Employee1 emp = new Employee1(); emp.setName("David"); emp.setRole("Developer"); emp.setInsertTime(new Date()); //Get Session SessionFactory sessionFactory = HibernateUtil.getSessionAnnotationFactory(); Session session = sessionFactory.getCurrentSession(); //start transaction session.beginTransaction(); //Save the Model object session.save(emp); //Commit transaction session.getTransaction().commit(); System.out.println("Employee ID="+emp.getId()); //terminate session factory, otherwise program won't end sessionFactory.close(); } } |
When we execute above program, we get following output.
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May 06, 2014 12:42:22 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit> INFO: HCANN000001: Hibernate Commons Annotations {4.0.4.Final} May 06, 2014 12:42:22 AM org.hibernate.Version logVersion INFO: HHH000412: Hibernate Core {4.3.5.Final} May 06, 2014 12:42:22 AM org.hibernate.cfg.Environment <clinit> INFO: HHH000206: hibernate.properties not found May 06, 2014 12:42:22 AM org.hibernate.cfg.Environment buildBytecodeProvider INFO: HHH000021: Bytecode provider name : javassist May 06, 2014 12:42:22 AM org.hibernate.cfg.Configuration configure INFO: HHH000043: Configuring from resource: hibernate-annotation.cfg.xml May 06, 2014 12:42:22 AM org.hibernate.cfg.Configuration getConfigurationInputStream INFO: HHH000040: Configuration resource: hibernate-annotation.cfg.xml May 06, 2014 12:42:23 AM org.hibernate.cfg.Configuration doConfigure INFO: HHH000041: Configured SessionFactory: null Hibernate Annotation Configuration loaded Hibernate Annotation serviceRegistry created May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!) May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://localhost/TestDB] May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000046: Connection properties: {user=pankaj, password=****} May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000006: Autocommit mode: false May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000115: Hibernate connection pool size: 20 (min=1) May 06, 2014 12:42:23 AM org.hibernate.dialect.Dialect <init> INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.internal.LobCreatorBuilder useContextualLobCreation INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 May 06, 2014 12:42:23 AM org.hibernate.engine.transaction.internal.TransactionFactoryInitiator initiateService INFO: HHH000399: Using default transaction strategy (direct JDBC transactions) May 06, 2014 12:42:23 AM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init> INFO: HHH000397: Using ASTQueryTranslatorFactory Employee ID=20 May 06, 2014 12:42:23 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop INFO: HHH000030: Cleaning up connection pool [jdbc:mysql://localhost/TestDB] |
Have a look at the output and compare it with the output from the XML based configuration, you will notice some differences. For example, we are not setting connection pool size for annotation based configuration, so it’s setting to default value 20.
Hibernate Java Configuration Test
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package com.journaldev.hibernate.main; import java.util.Date; import org.hibernate.Session; import org.hibernate.SessionFactory; import com.journaldev.hibernate.model.Employee1; import com.journaldev.hibernate.util.HibernateUtil; public class HibernateJavaConfigMain { public static void main(String[] args) { Employee1 emp = new Employee1(); emp.setName("Lisa"); emp.setRole("Manager"); emp.setInsertTime(new Date()); //Get Session SessionFactory sessionFactory = HibernateUtil.getSessionJavaConfigFactory(); Session session = sessionFactory.getCurrentSession(); //start transaction session.beginTransaction(); //Save the Model object session.save(emp); //Commit transaction session.getTransaction().commit(); System.out.println("Employee ID="+emp.getId()); //terminate session factory, otherwise program won't end sessionFactory.close(); } } |
Output of the above test program is:
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May 06, 2014 12:45:09 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit> INFO: HCANN000001: Hibernate Commons Annotations {4.0.4.Final} May 06, 2014 12:45:09 AM org.hibernate.Version logVersion INFO: HHH000412: Hibernate Core {4.3.5.Final} May 06, 2014 12:45:09 AM org.hibernate.cfg.Environment <clinit> INFO: HHH000206: hibernate.properties not found May 06, 2014 12:45:09 AM org.hibernate.cfg.Environment buildBytecodeProvider INFO: HHH000021: Bytecode provider name : javassist Hibernate Java Config serviceRegistry created May 06, 2014 12:45:09 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure WARN: HHH000402: Using Hibernate built-in connection pool (not for production use!) May 06, 2014 12:45:09 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000401: using driver [com.mysql.jdbc.Driver] at URL [jdbc:mysql://localhost/TestDB] May 06, 2014 12:45:09 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000046: Connection properties: {user=pankaj, password=****} May 06, 2014 12:45:09 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl buildCreator INFO: HHH000006: Autocommit mode: false May 06, 2014 12:45:09 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl configure INFO: HHH000115: Hibernate connection pool size: 20 (min=1) May 06, 2014 12:45:10 AM org.hibernate.dialect.Dialect <init> INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect May 06, 2014 12:45:10 AM org.hibernate.engine.jdbc.internal.LobCreatorBuilder useContextualLobCreation INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4 May 06, 2014 12:45:10 AM org.hibernate.engine.transaction.internal.TransactionFactoryInitiator initiateService INFO: HHH000399: Using default transaction strategy (direct JDBC transactions) May 06, 2014 12:45:10 AM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init> INFO: HHH000397: Using ASTQueryTranslatorFactory Employee ID=21 May 06, 2014 12:45:10 AM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop INFO: HHH000030: Cleaning up connection pool [jdbc:mysql://localhost/TestDB] |
That’s all for hibernate tutorial for beginners, I hope it will be enough to get you started. We will look into different features of Hibernate framework in future tutorials. Download the complete project from below link and play around with it to learn more.