There are several annotations in hibernate but here is the list of most used annotation with example code.
1: @Entity: In Hibernate, a Java class that corresponds to a database table is always present, and the @Entity annotation is used to identify the Java class as a matching database table that helps to establish a relationship between them.
2: @Id: This annotation is used If want to mark a property in entity as a Primary key.
3: @Table: By using @Table annotation, we can override (change) the table name, schema, index etc.
4: @GeneratedValue: It is used to set the strategies to generate the primary key value. The most common used strategies are AUTO, IDENTITY, SEQUENCE, and TABLE.
5: @Column: It is used to specify the column detailsin the table, such as the column name, length ,data type, etc.
6: @Transient: If we don’t want to save (persist) any field, we mark that field as transient, It indicates that it should not be persisted(saved) to the database table.
7: @Lob: it is used to save image type data in the database table
For better understanding, let’s create a Hibernate program that incorporates its usage.
Create a Maven Project with Group ID “com.hiber.myannotation” & artifact id “CommonUsedAnnotation”
pom.xml 👇
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.hiber.myannotation</groupId>
<artifactId>CommonUsedAnnotation</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>CommonUsedAnnotation</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.6.6.Final</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
</dependencies>
</project>
hibernate..cfg.xml
<?xml version = "1.0" encoding = "utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/myhiber</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name = "dialect">org.hibernate.dialect.MySQL5Dialect</property>
<property name="hbm2ddl.auto">update</property>
<property name="show_sql">true</property>
<mapping class="com.hiber.myannotation.Address"/>
</session-factory>
</hibernate-configuration>Address.java (Entity Class)
package com.hiber.myannotation;
import java.util.Arrays;
import java.util.Date;
import javax.annotation.processing.Generated;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Lob;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;
@Entity
@Table(name="student_address")
public class Address {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "address_id")
private int addressId;
@Column(length = 50, name = "STREET")
private String street;
@Column(length = 50, name="CITY")
private String city;
@Column(name="is_open")
private boolean isOpen;
@Transient
private double x;
@Column(name="added_date")
@Temporal(TemporalType.DATE)
private Date addedDate;
@Lob
private byte[] image;
public Address() {
super();
// TODO Auto-generated constructor stub
}
public Address(int addressId, String street, String city, boolean isOpen, double x, Date addedDate, byte[] image) {
super();
this.addressId = addressId;
this.street = street;
this.city = city;
this.isOpen = isOpen;
this.x = x;
this.addedDate = addedDate;
this.image = image;
}
public int getAddressId() {
return addressId;
}
public void setAddressId(int addressId) {
this.addressId = addressId;
}
public String getStreet() {
return street;
}
public void setStreet(String street) {
this.street = street;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public boolean isOpen() {
return isOpen;
}
public void setOpen(boolean isOpen) {
this.isOpen = isOpen;
}
public double getX() {
return x;
}
public void setX(double x) {
this.x = x;
}
public Date getAddedDate() {
return addedDate;
}
public void setAddedDate(Date addedDate) {
this.addedDate = addedDate;
}
public byte[] getImage() {
return image;
}
public void setImage(byte[] image) {
this.image = image;
}
@Override
public String toString() {
return "Address [addressId=" + addressId + ", street=" + street + ", city=" + city + ", isOpen=" + isOpen
+ ", x=" + x + ", addedDate=" + addedDate + ", image=" + Arrays.toString(image) + "]";
}
}
App.java (Main class)
package com.hiber.myannotation;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Date;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
/**
* Hello world!
*
*/
public class App
{
public static void main( String[] args ) throws IOException
{
System.out.println("Project Started");
//SessionFactory factory=new Configuration().configure("hibernate.cfg.xml").buildSessionFactory();
// Creating Student
Configuration cfg=new Configuration();
cfg.configure("hibernate.cfg.xml");
SessionFactory factory = cfg.buildSessionFactory();
// Address Object
Address address= new Address();
address.setStreet("Street C");
address.setCity("Delhi");
address.setOpen(true);
address.setAddedDate(new Date());
address.setX(12.343);
// reading image
FileInputStream fis=new FileInputStream("src/main/java/logof.png");
byte[] data=new byte[fis.available()];
fis.read(data);
address.setImage(data);
Session session = factory.openSession();
Transaction transaction = session.beginTransaction();
session.save(address);
transaction.commit();
session.close();
System.out.println("Done");
}
}
