czwartek, 13 czerwca 2013

Hibernate ralation: many to one(unidirectional)

1. Database schema

...

2. Entity class:

@Entity
@Table(name = "Shop")
public class Shop {

    @Id
    @GeneratedValue
    private Long id;

    @Column
    private String name;

    @Column
    private  String urlAddress;

    public Shop() {
    }


//getters and setters

}

import javax.persistence.*;

@Entity
@Table(name = "Provider")
public class Provider {

    @Id
    @GeneratedValue
    private Long id;

    @Column
    private String name;

    @ManyToOne(cascade = {CascadeType.ALL})
    @JoinColumn(name = "shopId")
    private Shop shop;

    public Provider() {
    }


//getters and setters

}

3. Hibernate configuration file

Put annotated classes User.java and UserAdditionalInfo.java in to hibernate configuration file and mysql connection details:

<?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>
        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/test</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>

        <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="hibernate.show_sql">true</property>

        <property name="hbm2ddl.auto">create-drop</property>

        <mapping class="net.hibernateApp.packt.maven.domain.Shop"/>
        <mapping class="net.hibernateApp.packt.maven.domain.Provider>"/>

    </session-factory>
</hibernate-configuration>

4. Run

import net.hibernateApp.packt.maven.domain.User;
import net.hibernateApp.packt.maven.domain.Product;
import net.hibernateApp.packt.maven.hibernate.HibernateUtils;
import org.hibernate.SessionFactory;
import org.hibernate.Session;

public class Main {

    public static void main(String[] args) {

        Shop shop = new Shop();
        shop.setName("Free Market");
        shop.setUrlAddress("http://...");

        Provider provider1 = new Provider();
        provider1.setName("google");
        provider1.setShop(shop);

        Provider provider2 = new Provider();
        provider2.setName("samsung");
        provider2.setShop(shop);

        saveProvider(provider1);
        saveProvider(provider2);

        List<Shop> shops = list("Shop");
        System.out.println(shops.size());
    }

 private static List list(String sourceTable) {
        SessionFactory sf = HibernateUtils.getSessionFactory();
        Session session = sf.openSession();
        List objects = session.createQuery("from "+sourceTable).list();
        session.close();
        return objects;
    }

    private static void saveProvider(Provider provider){
        SessionFactory sf;
        sf = HibernateUtils.getSessionFactory();
        Session session = sf.openSession();
        session.beginTransaction();
        Long id = (Long) session.save(provider);
        session.getTransaction().commit();
        session.close();
    }

}

Output: 1

Class net.hibernateApp.packt.maven.hibernate.HibernateUtils is described here:
 Using Hibernate persistence with Maven

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