Using NetBeans for Building Hibernate Based Web Applications

Overview

The web application that we are going to build is a DVD Store application that allows user to browse and rent out DVD titles. This tutorial shows how you can use hibernate as a persistence layer and interact with the DB containing some sample DVD title information. For the purpose of this tutorial, we will be using the Sakila DB, a sample DB that you can download from the MySQL site. Information for setting up the Sakila DB is provided in the following sections.

Hibernate Support in NetBeans

The following list enumerates the hibernate support in NetBeans IDE:

• Wizard based creation of hibernate configuration file.
• Wizard based creation of hibernate mapping file.
• Reverse engineering support.
• Support for creating POJO classes.
• Code generation for hibernate utility class.
• Code completion in hibernate mapping file and configuration file.
• HQL Editor.

Requirements for This tutorial

• NetBeans IDE 6.1 or higher – For reverse engineering tables, you need NetBeans IDE 6.5 or the latest development builds available from the Netbeans site.
• Netbeans-Hibernate Plug-in – Hibernate support for web application is not available by default. You need to download the plug-in to activate this support. Instructions for downloading the plug-in are available in the following sections.
• Sakila DB – Sakila DB is an optimized sample DB available from the MySQL site. Sakila DB has sample records that we can use in this tutorial. You can also create your own DB and try out this tutorial.

• Note – This tutorial uses MySQL Server. But you can use any supported DB server with NetBeans IDE for working with Hibernate based applications.

Getting Started

• DB Setup – The tutorial uses Sakila MySQL DB. Hence you need to have a MySQL Server running in your machine.
• NetBeans IDE Setup – You need to download the Hibernate plug-in.
• Runtime Support – Since the tutorial focuses on building a web application, you need a server to deploy the web application. You can either use Apache Tomcat as a web server or can use Glassfish Application Server.

Setting up Sakila MySQL DB

• sakila-schema.sql
• sakila-data.sql

Perform the following tasks, from the console/command line:

mysql –u root –p
<Enter MySQL root password.
mysql> source <path-to-sakila-schema.sql>
mysql> source <path-to-sakila-data.sql>

Sakila DB is now set up. For detailed instruction, refer to the MySQL Site. Once you have set up Sakila DB, from the NetBeans IDE, under Services tab, expand the Databases > MySQL Server at localhost:3306 node to find sakila entry as shown in the following figure:

Right click on sakila entry and click Connect to allow NetBeans IDE to establish the connection with the DB.

When you try to connect to Sakila DB, you will be prompted with a New Database Connection dialog box. Enter the MySQL connection information and click OK. If you are using WebStack in OpenSolaris OS, the default password for root is an empty string. For other platforms, provide the root password as applicable.

When NetBeans successfully connects with the DB, You can see the connection entry jdbc:mysql://localhost:3306/sakila [root on Default schema] under the Databases node.

You can browse the tables available in the DB by expanding the Tables node.

• Note – Creating DB Connection in NetBeans IDE is optional. You can perform this task even after setting up Hibernate support as shown later in this tutorial.

Now, we have successfully setup the DB for this tutorial. The next section deals with configuring NetBeans IDE to support Hibernate framework for web applications.

Setting up Hibernate Support

1. Click Tools > Plugins
2. Click Available Plugins Tab.
3. In the Search field, enter Hibernate.
4. Select Hibernate Support from the list and click Install.
5. Accept the license terms and install the plug-in.

• Note – If you are using NetBeans IDE 6.1, you will see Hibernate Support and Hibernate 3.2.5 Library. If you install Hibernate Support plug-in, all necessary Hibernate libraries are also downloaded. When you build your application, these libraries are copied to WEB-INF/lib directory in the web application archive (.war) file.

Setting up Server Runtime

Go to Services Tab and expand Servers node to verify if one of these servers is present. If you do not find any server, Go to Tools > Servers to add a server. If you are using OpenSolaris OS, you can install the complete AMP runtime and NetBeans IDE by downloading and installing the amp-dev IPS package.

Building a DVD Rental Application

Assuming that you have setup the tutorial environment, let us proceed with the project creation.

Creating a Web Application Project

For creating a web application with Hibernate support, perform the following tasks:

• Click File > New Project
• Under Web Categories, click Web and select Web Application under Projects.
• Click Next

• Enter DVDStore as the name of the project
• Click Next

• In the Server field, select Apache Tomcat 6.x Server
• In the Java EE Version field, accept the default entry (Java EE 5).
• Accept the context path as /DVDStore
• Click Next

• From the Frameworks list, select Hibernate 3.2.5
• In the Database Connection field, select jdbc:mysql://localhost:3306/sakila [root on Default schema]
• Accept other default values
• Click Finish

Explore the DVDStore project tree. Hibernate configuration file hibernate.cfg.xml is created under Source Packages > <default package>. This is a simple XML file that you can edit at any stage of your project.

Hibernate Configuration File (hibernate.cfg.xml)

Here is the snippet of 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 name="session1">
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/sakila</property>
    <property name="hibernate.connection.username">root</property>
    <property name="hibernate.connection.password">root</property>
    <property name="hibernate.show_sql">true</property>
    <property name="hibernate.current_session_context_class">thread</property>
  </session-factory>
</hibernate-configuration>

In the above mentioned snippet, we have added an additional property:

 <property name="hibernate.current_session_context_class">thread</property>

This is a required parameter to enable thread bound strategy for your hibernate configuration. For more information on Hibernate Sessions, read this document.

You can view the Hibernate configuration file using 2 views:

1. Design View (Default view) – An intuitive interface for managing Hibernate configuration. You can set Session Factory and Security related properties with the help of GUI windows.
2. XML View – If you are aware of the Hibernate configuration schema, you can directly use the XML View for adding/modifying properties.

In this tutorial, we are not going to manually add properties to this file to keep it simple. You will notice later in the tutorial that whenever we create Hibernate mapping files, this configuration file gets automatically updated.

Creating Java Classes

To create the Java class, perform the following tasks:

• Right click DVDStore project and select New > Java Class
• Enter Class Name as Film
• Enter Package name as dvdrental
• Accept the defaults
• Click Finish

Now that we have created the Film class, we need to add fields corresponding to the columns in the film table. You need not map all of the available columns in the table. Expand Source Packages > dvdrental to find the file Film.java. Make changes to the file as highlighted in the following snippet:

package dvdrental;

import java.io.Serializable;

public class Film implements Serializable {

    private int filmID;
    private String title;
    private String description;
    private String releaseYear;
    private Integer languageID;
    private Integer origLangID;
    private Integer rentalDuration;
    private Float rentalRate;
    private Integer length;
    private String rating;
    private String specialFeatures;
    private String lastUpdate;

}

Now you can add getters and setters for the fields. You don’t need to manually do this. Just right click on Film.java file and select Insert Code > Getters and Setters. Select all the check boxes and click Generate to generate the getters and setters for the variables.

• Note – Some records in the film table of Sakila DB has NULL values for original_language_id column. Hence you need to use a wrapper class (Integer) and not primitive type (int) while mapping fields.

Now take a look at the modified file:

public class Film implements Serializable {
    private int filmID;
    private String title;
    private String description;
    private String releaseYear;
    private Integer languageID;
    private Integer origLangID;
    private Integer rentalDuration;
    private Float rentalRate;
    private Integer length;
    private String rating;
    private String specialFeatures;
    private String lastUpdate;

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public int getFilmID() {
        return filmID;
    }

    public void setFilmID(int filmID) {
        this.filmID = filmID;
    }

    public Integer getLanguageID() {
        return languageID;
    }

    public void setLanguageID(Integer languageID) {
        this.languageID = languageID;
    }

    public String getLastUpdate() {
        return lastUpdate;
    }

    public void setLastUpdate(String lastUpdate) {
        this.lastUpdate = lastUpdate;
    }

    public Integer getLength() {
        return length;
    }

    public void setLength(Integer length) {
        this.length = length;
    }

    public Integer getOrigLangID() {
        return origLangID;
    }

    public void setOrigLangID(Integer origLangID) {
        this.origLangID = origLangID;
    }

    public String getRating() {
        return rating;
    }

    public void setRating(String rating) {
        this.rating = rating;
    }

    public String getReleaseYear() {
        return releaseYear;
    }

    public void setReleaseYear(String releaseYear) {
        this.releaseYear = releaseYear;
    }

    public Integer getRentalDuration() {
        return rentalDuration;
    }

    public void setRentalDuration(Integer rentalDuration) {
        this.rentalDuration = rentalDuration;
    }

    public Float getRentalRate() {
        return rentalRate;
    }

    public void setRentalRate(Float rentalRate) {
        this.rentalRate = rentalRate;
    }

    public String getSpecialFeatures() {
        return specialFeatures;
    }

    public void setSpecialFeatures(String specialFeatures) {
        this.specialFeatures = specialFeatures;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }   
}

• Note – In NetBeans 6.5 IDE, you do not need to manually create Java Class files. You can choose to create a Hibernate Reverse Engineering File as shown in the next section.

OR Mapping

In this section, we use the New File wizard to create a simple File.hbm.xml Hibernate mapping file for File.java class. You then need to edit the file in the XML editor to map the fields in the class to corresponding columns in the film table . You can use the IDE’ code completion feature to help you edit the mapping file.

To map film table to Film.java, perform the following tasks:

• Right Click dvdrental package and select New File > Other
• Click Hibernate under Categories section and select Hibernate Mapping File
• Click Next

• Note – In NetBeans 6.5 IDE, you do not need to manually create the mapping file. You can choose to create a Hibernate Reverse Engineering File as shown in the next section.

• Enter Film.hbm as the name of the mapping file
• Click Next

• Click … button in the Class to Map field to open the Find Type dialog box
• Search and Select Film (dvdrental) type and click OK

• In the Database Table drop down box, select the film table
• Verify if the Configuration File field has hibernate.cfg.xml value
• Click Finish

Just like the Hibernate configuration file, code completion is available for hibernate mapping file too.

The following figures show code completion feature for the hibernate mapping file:

Make changes to Film.hbm.xml file to map the fields as shown in the snippet below:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" 
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class dynamic-insert="false" dynamic-update="false" mutable="true" name="dvdrental.Film" 
optimistic-lock="version" polymorphism="implicit" select-before-update="false" table="film">
        <id column="film_id" name="filmID">
            <generator class="increment"/>
        </id>
        
        <property column="description" name="description"/>
        <property column="language_id" name="languageID"/>
        <property column="last_update" name="lastUpdate"/>
        <property column="length" name="length"/>
        <property column="original_language_id" name="origLangID"/>
        <property column="rating" name="rating"/>
        <property column="release_year" name="releaseYear"/>
        <property column="rental_duration" name="rentalDuration"/>
        <property column="rental_rate" name="rentalRate"/>
        <property column="special_features" name="specialFeatures"/>
        <property column="title" name="title"/>
        
    </class>
</hibernate-mapping>

In this section, we created a mapping file for the film table, but for our sample, we need to create similar mapping files for other Sakila tables including actor, category and language tables. We will use the reverse engineering feature available from NetBeans IDE 6.5 to map these tables as shown in the next section.

Reverse Engineering (NetBeans 6.5)

For creating a Hibernate reverse engineering file, perform the following tasks:

• Right click dvdrental source package and select New File > Other
• Under Hibernate category, select Hibernate Reverse Engineering File
• Click Next

• Enter File Name as hibernate.reveng
• Accept the defaults and click Next

Now you need to choose the tables for which you need to map.

• From the Available Tables, select actor, category, language, film_actor, and film_category and click Add>
• Click Next

• In the General Settings, click Java5 Syntax as our project is a simple web application and does not contain any EJB
• In the Code Generation Settings, select both Domain Code and Hibernate XML Mappings since we need to generate both the Java classes and the mapping files
• Accept other default values
• Click Finish

Now check your hibernate.cfg.xml file to see the mappings in place:

    ....
    <mapping resource="dvdrental/Language.hbm.xml"/>
    <mapping resource="dvdrental/Actor.hbm.xml"/>
    <mapping resource="dvdrental/FilmActor.hbm.xml"/>
    <mapping resource="dvdrental/FilmCategory.hbm.xml"/>
    <mapping resource="dvdrental/Category.hbm.xml"/>
    ....

Connecting to DB Using Hibernate Utility

• Right click dvdrental source package and select New File > Other
• Under Hibernate category, select HibernateUtil.java
• Click Next
• Provide HibernateUtil as the File Name
• Click Finish

The following code snippet shows the content of the HibernateUtil.java file. We won’t be modifying this file in this tutorial.

package dvdrental;

import org.hibernate.cfg.Configuration;
import org.hibernate.SessionFactory;

public class HibernateUtil {
    private static final SessionFactory sessionFactory;
    static {
        try {
            // Create the SessionFactory from standard (hibernate.cfg.xml) 
            // config file.
            sessionFactory = new Configuration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Log the exception. 
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

Creating Helper Application

For creating this helper class, perform the following tasks:

• Right click dvdrental source package and select New > Java Class
• Enter FilmHelper as the Class Name
• Click Finish

In the FilmHelper.java file, we will be adding helper methods to query the DB as shown in the following sections. Refer to the dvdrental/FilmHelper.java for the complete code.

Enumerating DVD Titles (Using HQL)

In FilmHelper.java, add the following method:

    public List getFilmTitles(int startID, int endID) {
        List<Film> filmList = null;
        try {            
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery 
	("from Film as film where film.filmID between '"+startID+"' and '"+endID+"'");
            filmList = (List<Film>) q.list();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return filmList;
    }

Enumerating Actors (Using HQL Sub Queries)

The example shown in the following snippet shows a sub query for fetching records from both actor and film_actor table:

    public List getActorsByID(int filmID){
        List<Actor> actorList = null;
        try {
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery
            ("from Actor as actor where actor.actorID in 
	(select actorID from FilmActor filmActor where    
            filmActor.filmID='"+filmID+"')");
            actorList = (List<Actor>) q.list();

        } catch (Exception e) {
            e.printStackTrace();
        }

        return actorList;
    }

Introduction to HQL Editor (NetBeans 6.5 IDE)

To invoke the HQL Editor, perform the following tasks:

• Right click hibernate.cfg.xml file and select Run HQL Query

The following figure shows the HQL editor. The top panel contains the text area where you can build your HQL queries. For executing the query, click on the icon with a green arrow mark (next to the session field) as shown in the figure.

You can also view the correponding SQL query by clicking the SQL button.

FilmHelper.java

package dvdrental;

import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;

public class FilmHelper {
    
    Session session = null;

    public FilmHelper() {
        this.session = HibernateUtil.getSessionFactory().getCurrentSession();
    }

    public List getFilmTitles(int startID, int endID) {
        List<Film> filmList = null;
        try {            
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery
	("from Film as film where film.filmID between '"+startID+"' and '"+endID+"'");
            filmList = (List<Film>) q.list();

        } catch (Exception e) {
            e.printStackTrace();
        }

        return filmList;

    }
    
    public List getActorsByID(int filmID){
        List<Actor> actorList = null;
        try {
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery
	("from Actor as actor where actor.actorID in 
	(select actorID from FilmActor filmActor where filmActor.filmID='"+filmID+"')");
            actorList = (List<Actor>) q.list();

        } catch (Exception e) {
            e.printStackTrace();
        }

        return actorList;
    }
    
    public Category getCategoryByID(int filmID){
        List<Category> categoryList = null;
        try {
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery
	("from Category as category where category.categoryID in 
	(select categoryID from FilmCategory filmCat where filmCat.filmID='"+filmID+"')");
            categoryList = (List<Category>) q.list();

        } catch (Exception e) {
            e.printStackTrace();
        }

        return categoryList.get(0);
    }
    
    public Film getFilmByID(int filmID){
        
        Film film = null;
        List<Film> filmList = null;
        
        try {
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery
	("from Film as film where film.filmID='"+filmID+"'");
            filmList = (List<Film>) q.list();
            film = (Film) filmList.get(0);
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return film;
    }
    
    public String getLangByID(int langID){
        
        String language = null;
        List<Language> langList = null;
        
        try {
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery
	("from Language as lang where lang.languageID='"+langID+"'");
            langList = (List<Language>) q.list();
            language = ((Language) langList.get(0)).getLanguage();
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return language;
    }
}

We will be invoking the methods in this class from the JSP files we build in the next section.

Creating the Web Interface

To create the JSP file, perform the following tasks:

• Right click on the DVDStore node and select New > JSP
• Enter browse.jsp as the name of the JSP file
• Click Finish

In browse.jsp file add the following snippet:

<%
            //Get title ID
            int filmID = 1;
            if (request.getParameter("id") != null) {
                filmID = Integer.parseInt(request.getParameter("id"));
            }
%>
<%
            boolean startPage = false;
            boolean endPage = false;
                
            FilmHelper helper = new FilmHelper();
            Film film = helper.getFilmByID(filmID);

            String filmTitle = film.getTitle();
            String filmDescription = film.getDescription();
            
            //Get Actors
            List actors = helper.getActorsByID(filmID);
            StringBuffer totalCast = new StringBuffer();
            
            //Get Category
            Category category = helper.getCategoryByID(filmID);
            String catName = category.getName();
            
            for(int i=0;i<actors.size();i++){
                Actor actor = (Actor)actors.get(i);
                totalCast.append(actor.getFirstName());
                totalCast.append(" ");
                totalCast.append(actor.getLastName());
                totalCast.append("  ");
            }

            int langID = film.getLanguageID();
            String language = helper.getLangByID(langID);
            int filmLength = film.getLength();
            String filmRating = film.getRating();
            String filmYear = film.getReleaseYear();

            int rentalDuration = film.getRentalDuration().intValue();
            float rentalRate = film.getRentalRate().floatValue();
            String specialFeatures = film.getSpecialFeatures();
            
            …..
%>

Check the source of index.jsp for the complete code. Also this tutorial does not show you how to create Style sheets (CSS). Download the tutorial bundle and check out these files.

Also check out the code of index.jsp that displays the available DVDs.

Running the Application

• Download the DVDStore project and open the project in NetBeans IDE 6.5.
• Right click the DVDStore node and select Build.
• After the build process is complete, right click the DVDStore node and select Run.

If the web browser does not start automatically, access the application at:

http://localhost:8080/DVDStore/

The following figure shows the main page. Click any title to view the DVD information.

Detailed information about the DVD is displayed on this page. Click Rent Out to rent out the DVD.

Troubleshooting

MySQL Driver Not Found

• Right click DVDStore node and click Properties
• Click Libraries from the Categories section
• Click Add Library, select MySQL JDBC Driver and click OK

OutOfMemoryError: PermGen Space

Download the Sample

In hibernate.cfg.xml, you need to modify the MySQL connection information to make the application work.

Reference

• Hibernate Support in NetBeans IDE
• Using Hibernate with Visual Web Projects
• Using Hibernate with JPA
• Hibernate Mapping Wizard
• Hibernate Configuration Wizard
• Sakila DB
• MySQL DB Server

Attachments

DVDStore.zip		4204799 bytes
dvdstore1.PNG		27385 bytes
dvdstore2.PNG		19043 bytes
hbmaid1.png		22358 bytes
hbmaid2.png		42986 bytes
hiberutil.png		40875 bytes
hqleditor1.png		26842 bytes
hqleditor2.png		31860 bytes
mapping1.png		44683 bytes
mapping2.png		33423 bytes
mapping3.png		18684 bytes
mapping4.png		34485 bytes
nb65_newconfig.png		38040 bytes
nb65_newmapping.png		38065 bytes
nb65_newreverse.png		38343 bytes
nb65_newreverse2.png		29027 bytes
nb65_newreverse3.png		31608 bytes
nb65_newreverse4.png		32158 bytes
nb65_newutil.png		38410 bytes
nb65_plugin1.png		32508 bytes
newproject1.png		46676 bytes
newproject2.png		43849 bytes
newproject3.png		36642 bytes
newproject4.png		45530 bytes
plugin_install.png		56800 bytes
plugin_install2.png		20773 bytes
pojo1.png		31969 bytes
pojo2.png		19702 bytes
prereq1.png		38672 bytes
sakila_nbview1.png		20260 bytes
sakila_nbview2.png		21452 bytes
sakila_nbview3.png		22119 bytes
sakila_nbview4.png		20228 bytes