hibernate-tutorial3

Hibernate Annotations

Description

A sample code to use Hibernate in Annotations mode

• JavaSE 8
• Hibernate 5 / Annotations
• Maven 4
• MySQL 5

1. Database (the same in Tutorial 2)

We will use the same database / table

2. Maven "pom.xml" dependencies

<dependencies>
    <!-- MySQL connector -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>6.0.6</version>
    </dependency>
    <!-- Hibernate -->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.2.11.Final</version>
    </dependency>
</dependencies>

3. Changes in "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>
        <!-- MySQL -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/persist_db?useTimezone=true&amp;serverTimezone=UTC</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password"></property>

        <!-- Hibernate -->
        <property name="show_sql">true</property>
        <property name="format_sql">false</property>
        <property name="hibernate.hbm2ddl.auto">update</property>

        <!-- Entities -->
        <mapping class="net.isetjb.hibernatetutorial3.Product"/>
    </session-factory>
</hibernate-configuration>

• hibernate.hbm2ddl.auto : update => update the database schema with defined entities
• hibernate.hbm2ddl.auto : create => creates the schema necessary for defined entities, destroying any previous data

3. No "Product.hbm.xml" file

There is no "Product.hbm.xml" mapping file. To do mapping we will use Hibernate Annotations instead

4. Annotations in POJO classes "Product.java"

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "product")
public class Product
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private int id;

    @Column(name = "name", length = 255, nullable = true)
    private String name;

    @Column(name = "price", nullable = true)
    private int price;

    // GETTERs and SETTERs here...
}

• @Entity : link to the "Product" class (Bean / POJO)
• @Table : table that will be used to persist the entity in the database
• @Id : primary key
• @GeneratedValue : generation type for the primary key (ex : AUTO_INCREMENT in MySQL)
• @Column : details of the column to which a property will be mapped

5. Class "Application.java"

Use exactly "Application.java" in Tutorial 2 to test