Hibernate example of insert/select blob from database

In previous hibernate tutorials, we have learned about first level cache, second level cache and some various mapping examples etc. This is complete list of hibernate related tutorials. In this post, I am giving an example of inserting BLOB data into database using hibernate and getting this data from database, using hibernate entities.

Lets take an example, in which, I am inserting “test.png” image from windows C drive to database (MySQL). Then I will read the image data again from database and store it to different location.

Hibernate entity

Please note, I have declared the data field as byte[].

@Entity
@Table(name = "TBL_IMAGES")
public class ImageWrapper implements Serializable {
	
	private static final long serialVersionUID = 1L;

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "ID", unique = true, nullable = false)
	private Integer id;
	
	@Column(name = "IMAGE_NAME", unique = false, nullable = false, length = 100)
	private String imageName;
	
	@Column(name = "DATA", unique = false, nullable = false, length = 100000)
	private byte[] data;
	
	//Getters and Setters
}

Inserting blob data into database

Let’s look at the code:

	Session session = HibernateUtil.getSessionFactory().openSession();
	session.beginTransaction();
		
	File file = new File("C:\test.png");
	byte[] imageData = new byte[(int) file.length()];

	try {
		FileInputStream fileInputStream = new FileInputStream(file);
		fileInputStream.read(imageData);
		fileInputStream.close();
	} catch (Exception e) {
		e.printStackTrace();
	}

	ImageWrapper image = new ImageWrapper();
	image.setImageName("test.jpeg");
	image.setData(imageData);

	session.save(image);	//Save the data
	
	session.getTransaction().commit();
	HibernateUtil.shutdown();

After executing above code, you can verify that a table into database is created if it’s not already there. And one BLOB column is created to hold the image data.

Reading the blob data from database

This is simple, and in fact you do not need to do anything extra. Above entity definition will work fine.

	Session session = HibernateUtil.getSessionFactory().openSession();
	session.beginTransaction();
	
	ImageWrapper imgNew = (ImageWrapper)session.get(ImageWrapper.class, 1);
	byte[] bAvatar = imgNew.getData();

	try{
		FileOutputStream fos = new FileOutputStream("C:\temp\test.png"); 
		fos.write(bAvatar);
		fos.close();
	}catch(Exception e){
		e.printStackTrace();
	}

	session.getTransaction().commit();
	HibernateUtil.shutdown();

Hibernate configuration

For reference, This is the configuration I am using for this example:

hibernate.cfg.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>
        <property name="hibernate.connection.password">password</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="show_sql">true</property>
		<property name="hibernate.hbm2ddl.auto">create</property>
        <mapping class="hibernate.test.dto.ImageWrapper"></mapping>
    </session-factory>
</hibernate-configuration>

Also below is the code for HibernateUtil.java

HibernateUtil.java

public class HibernateUtil {
	private static final SessionFactory sessionFactory = buildSessionFactory();
	 
    @SuppressWarnings("deprecation")
	private static SessionFactory buildSessionFactory() {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            return new AnnotationConfiguration().configure(new File
            		("D:\Latest Setup\eclipse_juno_workspace\hibernate-test-project\hibernate.cgf.xml"))
            		.buildSessionFactory();
 
        }
        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);
        }
    }
 
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
 
    public static void shutdown() {
    	getSessionFactory().close();
    }
}

If still feeling trouble, download the sourcecode attached.

Happy Learning !!