LAB-3513: Building Hibernate Application Step By Step

In this exercise, you are going to start the Derby database server and create "mydatabase" database.

Start Java DB (code-named as Derby) database server
Create a database of your own called "mydatabase
Install Hibernate plug-in to the NetBeans IDE (works only for NetBeans IDE 6.1)

1. Select Java DB Server. (Figure-0.10 below)

Select Services tab.
Expand Databases.
Right click Java DB and select Start Server. If it has been already started, it should be grayed out.

Figure-0.10: Start the Derby database server

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1. Create database

Right click Java DB and select Create Database. (Figure-0.20 below)

Figure-0.20: Create mydatabase database

2. Fill up the fields of the Create Java DB Database dialog box.

For the Database Name field, type in "mydatabase".
For Password field, type in "app". (Figure-0.21 below)
Click OK.

Figure-0.21: Create Java DB Database

3. Make a connection to the mydatabase database. Note that you have not created any tables yet under this database.

Expand Drivers.
Right click Java DB (Network) and select Connect Using...

Observe that the New Database Connection dialog box appears.
For the Database URL field, type in jdbc:derby://localhost:1527/mydatabase.
For the User Name and Password firled, type in app.
Click OK.

Observe that there is now jdbc:derby://localhost:1527/mydatabase [app on APP] under Databases. (Figure-0.22 below)

Figure-0.22: Observe that mydatabase database is created

Click Projects tab window to go back to display the project view of the project

The Hibernate plug-in is available only for NetBeans 6.1.

In this simple application, there is only one POJO class to write. The name of the POJO class is Person.java.

1. Create a new NetBeans project

Select File->New Project (Ctrl+Shift+N). (Figure-1.11 below)

Figure-1.11: Create a new project

Observe that the New Project dialog box appears.
Under Choose Project pane, select Java under Categories and Java Application under Projects. (Figure-1.12 below)
Click Next.

Figure-1.12: Create Java Application project

Under Name and Location pane, for the Project Name field, type in HibernateHelloWorld.
For Create Main Class field, type in Main. (Figure-1.13 below)
Click Finish.

Figure-1.13: Give a project name

Observe that HibernateHelloWorld project appears and IDE generated Main.java is displayed in the source editor window of NetBeans IDE. You are going to modify the Main.java later on.

2. Write Person.java as shown in Code-1.14 below. Note that this is a POJO class.

Right click HibernateHelloWorld project node and select New->Java Class.
Observe the New Java Class dialog box appears.
For the Class Name field, enter Person.
For Package field, leave it as a blank field. You are going to use default package by leaving it a blank field. (Using a package is usually a better practice but in this exercise, we are using the default package for the sake of simplicity of the exercise.)
Click Finish. (Figure-1.14 below)

Figure-1.14: Name and Location pane

Modify the IDE generated Person.java with the code of Code-1.15 below. You can copy and paste the code.

import java.io.Serializable;

public class Person implements Serializable {

    private int id;
    private String name;

    protected Person() {
    }

    public Person(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

Code-1.15: Person.java

Since there is only one POJO class, Person class, in this application, you are going to write a single mapping file. (Actually, a single mapping file can contain mapping information of multiple POJO classes but it is a good practice to have a separate mapping file for each POJO class.)

1. Write Person.hbm.xml.

In this mapping file, you will specify that Person class is mapped to a database table called person. The id field of the Person class will be used as a primary key field in the person database table. The name field will have a corresponding column called cname.

Right click HibernateHelloWorld project node and select New->Other. (Figure-1.21 below)

Figure-1.21: Create XML file

Observe that Choose File Type pane appears.
Choose XML under Categories section on the left and XML Document under File Types on the right. (Figure-1.22 below)
Click Next.

Figure-1.22: Create XML Document

Observe that Name and Location pane appears.
For File Name field, enter Person.hbm. (Figure-1.23 below)
Click Browse for Folder.

Figure-1.23: Specify the folder in which the file gets created

Observe that the Browse Folders dialog box appears.
Select src node.
Click Select Folder. (Figure-1.24 below)

Figure-1.24: Select src

Click Next. (Figure-1.25 below)

Figure-1.25: Click Next.

Observe that the Select Document Type pane appears.
Click Finish. (Figure-1.26 below)

Figure-1.26: Finish creation of XML document

Observe IDE generated XML file is displayed in the editor window.
Replace the template XML file with the contents of the Code-1.27 below.
Study the code by paying special attention to the bold fonted parts.

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-mapping
   PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

   <class name="Person" table="person">
      <id name="id" type="int">
         <generator class="increment"/>
      </id>

      <property name="name" column="cname" type="string"/>
   </class>

</hibernate-mapping>

Code-1.27: Person.hbm.xml

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The Hibernate configuration file is for each application. You specify database connection setting information along with names of the mapping files in this file. Except the names of the mapping files, most Hibernate applications will share the same Hibernate configuration file.

1. Write hibernate.cfg.xml.

Right click HibernateHelloWorld project node and select New->XML Document.
Observe that Name and Location pane appears.
For File Name field, enter hibernate.cfg.
Click Browse for Folder.

Observe that the Browse Folders dialog box appears.
Select src node.
Click Select Folder.
Click Next (of the Name and Location pane).

Observe that the Select Document Type pane appears.
Click Finish.

Observe IDE generated XML file is displayed in the editor window.
Replace the template XML file with the contents of the Code-1.31 below.

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        
        <property name="connection.driver_class">org.apache.derby.jdbc.ClientDriver</property>
        <property name="connection.url">jdbc:derby://localhost:1527/mydatabase</property>
        <property name="connection.username">app</property>
        <property name="connection.password">app</property>

        
        <property name="connection.pool_size">1</property>

        
        <property name="dialect">org.hibernate.dialect.DerbyDialect</property>

        
        <property name="show_sql">false</property>

        
        <mapping resource="Person.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

Code-1.31: hibernate.cfg.xml

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1. Modify IDE generated Main.java as shown in Code-1.21 below. Study the code by paying special attention to the bold fonted parts.

Since you have not added Hibernate library files to the classpath, you will see bunch of compile errors (red boxes) detected by the IDE. Don't worry about these compile errors for now. We will add the Hibernate library files during the subsequent step.

In the main() method of the Main class, object instance is created and persisted through Session object of the Hibernate.

import org.hibernate.*;
import org.hibernate.cfg.Configuration;

public class Main {

    public static void main(String[] args) {

        // Set up database tables
        HibernateUtil.droptable("drop table person");
        HibernateUtil.setup("create table person ( id int, cname VARCHAR(20))");

        // Create SessionFactory and Session object
        SessionFactory sessions = new Configuration().configure().buildSessionFactory();
        Session session = sessions.openSession();

        // Perform life-cycle operations under a transaction
        Transaction tx = null;
        try {
            tx = session.beginTransaction();

            // Create a Person object and save it
            Person p1 = new Person();
            p1.setName("Sang Shin");
            session.save(p1);

            // Create another Person object and save it.
            Person p2 = new Person();
            p2.setName("Young Shin");
            session.save(p2);

            // Retrieve the person objects
            Person person = (Person)session. get(Person.class, p1.getId());
            System.out.println("First person retrieved = " + person.getName());
            person = (Person)session.get(Person.class, p2.getId());
            System.out.println("Second person retrieved = " + person.getName());

            tx.commit();
            tx = null;
        } catch ( HibernateException e ) {
            if ( tx != null ) tx.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }

        // Display tables
        HibernateUtil.checkData("select * from person");

    }

}

Code-1.41: Person.hbm.xml

2. Write HibernateUtil.java as shown in Code-1.42 below.

This is a utility class you will use for testing and debugging purpose. In this lab, you are going to use this utility class for creating and displaying database tables. Use this utility class in other Hibernate projects at your convenience. It is not really important for you to read this code.

Right click HibernateHelloWorld project node and select New->Java Class.
Observe that the Name and Location pane appears.
For the Class Name field, enter HibernateUtil. (Figure-1.42 below)
Click Finish.

Figure-1.42: Create HibernateUtil.java

Replace the IDE generated HibernateUtil.java with the one in Code-1.43 below.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;

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

public class HibernateUtil {

    // Database configuration
    public static String url = "jdbc:derby://localhost:1527/mydatabase";
    public static String dbdriver = "org.apache.derby.jdbc.ClientDriver";
    public static String username = "app";
    public static String password = "app";

    public static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            sessionFactory = new Configuration().configure().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 final ThreadLocal session = new ThreadLocal();

    public static Session currentSession() throws HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this thread has none yet
        if (s == null) {
            s = sessionFactory.openSession();
            // Store it in the ThreadLocal variable
            session.set(s);
        }
        return s;
    }

    public static void closeSession() throws HibernateException {
        Session s = (Session) session.get();
        if (s != null)
            s.close();
        session.set(null);
    }

    static Connection conn;
    static Statement st;

    public static void setup(String sql) {
        try {
            createStatement();
            st.executeUpdate(sql);
        } catch (Exception e) {
            System.err.println("Got an exception! ");
            e.printStackTrace();
            System.exit(0);
        }
    }

    public static void createStatement() {
        try {
            Class.forName(dbdriver);
            conn = DriverManager.getConnection(url, username, password);
            st = conn.createStatement();
        } catch (Exception e) {
            System.err.println("Got an exception! ");
            e.printStackTrace();
            System.exit(0);
        }
    }

    // Drop table if exists
    public static void droptable(String sql) {
        try {
            createStatement();
            st.executeUpdate(sql);
        } catch (Exception e) {
        }
    }

    public static void checkData(String sql) {
        String[] starray = sql.split(" ");
        System.out.println("\n******** Table: " + starray[starray.length-1] + " *******");
        try {
            createStatement();
            ResultSet r = st.executeQuery(sql);
            HibernateUtil.outputResultSet(r);
//            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void outputResultSet(ResultSet rs) throws Exception{
        ResultSetMetaData metadata = rs.getMetaData();

        int numcols = metadata.getColumnCount();
        String[] labels = new String[numcols];
        int[] colwidths = new int[numcols];
        int[] colpos = new int[numcols];
        int linewidth;

        linewidth = 1;
        for (int i = 0; i < numcols; i++) {
            colpos[i] = linewidth;
            labels[i] = metadata.getColumnLabel(i + 1); // get its label
            int size = metadata.getColumnDisplaySize(i + 1);
            if (size > 30 || size == -1)
                size = 30;
            int labelsize = labels[i].length();
            if (labelsize > size)
                size = labelsize;
            colwidths[i] = size + 1; // save the column the size
            linewidth += colwidths[i] + 2; // increment total size
        }

        StringBuffer divider = new StringBuffer(linewidth);
        StringBuffer blankline = new StringBuffer(linewidth);
        for (int i = 0; i < linewidth; i++) {
            divider.insert(i, '-');
            blankline.insert(i, " ");
        }
        // Put special marks in the divider line at the column positions
        for (int i = 0; i < numcols; i++)
            divider.setCharAt(colpos[i] - 1, '+');
        divider.setCharAt(linewidth - 1, '+');

        // Begin the table output with a divider line
        System.out.println(divider);

        // The next line of the table contains the column labels.
        // Begin with a blank line, and put the column names and column
        // divider characters "|" into it. overwrite() is defined below.
        StringBuffer line = new StringBuffer(blankline.toString());
        line.setCharAt(0, '|');
        for (int i = 0; i < numcols; i++) {
            int pos = colpos[i] + 1 + (colwidths[i] - labels[i].length()) / 2;
            overwrite(line, pos, labels[i]);
            overwrite(line, colpos[i] + colwidths[i], " |");
        }
        System.out.println(line);
        System.out.println(divider);

        while (rs.next()) {
            line = new StringBuffer(blankline.toString());
            line.setCharAt(0, '|');
            for (int i = 0; i < numcols; i++) {
                Object value = rs.getObject(i + 1);
                if (value != null){
                    overwrite(line, colpos[i] + 1, value.toString().trim());
                    overwrite(line, colpos[i] + colwidths[i], " |");
                }
            }
            System.out.println(line);
        }
        System.out.println(divider);

    }

    static void overwrite(StringBuffer b, int pos, String s) {
        int len = s.length();
        for (int i = 0; i < len; i++)
            b.setCharAt(pos + i, s.charAt(i));
    }

}

Code-1.43: HibernateUtil.java

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1. Right click HibernateHelloWorld project and select Properties. (Figure-1.61 below)

Figure-1.61: Select Properties of the project

2. Add Hibernate library

Select Libraries under Categories section on the left and select Add Library button on the right. (Figure-1.62 below)

Figure-1.62: Select Add Library

Select Hibernate library.
Click Add Library button. (Figure-1.63 below)

Figure-1.63: Add HibernateCore library

3. Add Java DB library.

Click Add Library button.

Select Java DB Driver.
Click Add Library.

Click OK.

Figure-1.64: Close the Project Properties

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This is optional step. If you don't have log4j.properties file in the class path of your project, you will get some warning messages, which you can ignore for now.

1. Add log4j.properties file.

Right click HibernateHelloWorld project node and select New->Other.
Choose Other under Categories section on the left and Empty File under File Types on the right.
Click Next.

Observe that Name and Location pane appears.
For File Name field, enter log4j.properties.
Click Browse on the Folder.

Observe that the Browse Folders dialog box appears.
Select src.
Click Select Folder.

Click Finish.

Observe empty file is displayed in the editor window.
Copy the contents of the Code-1.71 below and paste it to the empty file.

#
# Log4J Settings for log4j 1.2.x (via jakarta-commons-logging)
#
# The five logging levels used by Log are (in order):
#
#   1. DEBUG (the least serious)
#   2. INFO
#   3. WARN
#   4. ERROR
#   5. FATAL (the most serious)

# Set root logger level to WARN and append to stdout
log4j.rootLogger=WARN, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%d %5p (%c:%L) - %m%n

# Print only messages of level ERROR or above in the package noModule.
log4j.logger.noModule=FATAL

# OpenSymphony Stuff
log4j.logger.com.opensymphony=INFO
log4j.logger.com.opensymphony.webwork=DEBUG

# Spring Stuff
log4j.logger.org.springframework=INFO

Code-1.71: log4j.properties file

Now you are ready to build and run the application.

1. Right click HibernateHelloWorld project and select Run. (Figure-1.81 below)

Figure-1.81: Run Project

2. Observe the result in the Output window of the IDE. (Figure-1.82 below) The first part of the result is the output from the persistence operation through Hinernate and the second part is the display of the rows of the person table.

Figure-1.82: Result of performing database operation through Hibernate

Trouble-shooting: If you see the following error condition in the Output window, it is highly likely due to the fact the database server is not running.

15   [main] WARN org.hibernate.cfg.SettingsFactory - Could not obtain connection metadata
org.apache.derby.client.am.DisconnectException: java.security.PrivilegedActionException : Error opening socket to server localhost on port 1527 with message : null
        at org.apache.derby.client.net.NetAgent.<init>(Unknown Source)
        at org.apache.derby.client.net.NetConnection.newAgent_(Unknown Source)
        at org.apache.derby.client.am.Connection.<init>(Unknown Source)
        at org.apache.derby.client.net.NetConnection.<init>(Unknown Source)
        at org.apache.derby.jdbc.ClientDriver.connect(Unknown Source)
        at java.sql.DriverManager.getConnection(DriverManager.java:582)
        at java.sql.DriverManager.getConnection(DriverManager.java:154)
        at org.hibernate.connection.DriverManagerConnectionProvider.getConnection(DriverManagerConnectionProvider.java:110)
        at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:76)
        at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1933)
        at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1216)
        at HibernateUtil.<clinit>(HibernateUtil.java:26)
        at Main.main(Main.java:9)
Got an exception!

Solution: Start the database server as described in Exercise 0 above.

Trouble-shooting: If you see the following error condition in the Output window, it is highly likely due to the fact the client driver, derbyclient.jar for the Derby database, is not added to the classpath.

Initial SessionFactory creation failed.org.hibernate.HibernateException: JDBC Driver class not found: org.apache.derby.jdbc.ClientDriver
Exception in thread "main" java.lang.ExceptionInInitializerError
        at HibernateUtil.<clinit>(HibernateUtil.java:30)
        at Main.main(Main.java:9)
Caused by: org.hibernate.HibernateException: JDBC Driver class not found: org.apache.derby.jdbc.ClientDriver
        at org.hibernate.connection.DriverManagerConnectionProvider.configure(DriverManagerConnectionProvider.java:66)
        at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:124)
        at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:56)
        at org.hibernate.cfg.SettingsFactory.createConnectionProvider(SettingsFactory.java:397)
        at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:62)
        at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1933)
        at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1216)
        at HibernateUtil.<clinit>(HibernateUtil.java:26)
        ... 1 more

Solution: Add the client driver, derbyclient.jar, to the classpath as described in step 1.5 above.

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In this step, you are going to see if the person table is in fact populated with two rows that have been added in the Main class.

1. Select Services tab window.
2. Expand Databases.
3. Right click jdbc:derby://localhost:1527/mydatabase [app on APP] and select Connect. (Figure-1.91 below)

Figure-1.91: Connect to the database

4. Expand Tables.
5. Right click PERSON table and select View Data. (Figure-1.92 below)

Figure-1.92: View Data of the PERSON table

6. Observe that the two rows are present in the PERSON database table. (Figure-1.93 below)

Figure-1.93: Verify the contents of the database table.

Solution: This exercise up to this point is provided as a ready-to-open-and-run NetBeans project as part of hands-on lab zip file. You can find it as <LAB_UNZIPPED_DIRECTORY>/hibernatestepbystep/samples/HibernateHelloWorld. You will have to add Hibernate library files and client driver once you opened the project as described in this exercise above.

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In this exercise, you have learned how to build a simple HelloWorld Hibernate application from scratch. You learned Hibernate application typically has domain classes, corresponding mapping files for those domain classes, and Hibernate configuration file.

1. Right-click HibernateHelloWorld project and select Copy Project. (Figure-2.10 below)

Figure-2.10: Copy Project

2. Give a project name to the new project.

Observe that the Copy Project dialog box appears.
For the Project Name: field, type in HibernateHelloWorld2.
Click Copy. (Figure-2.11 below)

Figure-2.11: Copy Project

Observe that HibernateHelloWorld2 project node appears.

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In this step, you are going to add a new POJO domain class called Student.

1. Write Student.java.

import java.io.Serializable;

public class Student implements Serializable {

    private int id;
    private String school;
    private String grade;

    protected Student() {
    }

    public Student(int id, String school) {
        this.id = id;
        this.school = school;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getSchool() {
        return school;
    }

    public void setSchool(String name) {
        this.school = name;
    }

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

}

Code-2.21: Student.java

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1. Write Student.hbm.xml as shown in Code-2.31 below.

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-mapping
   PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

   <class name="Student" table="student">
      <id name="id" type="int">
         <generator class="increment"/>
      </id>

      <property name="school" column="schoolname" type="string"/>
      <property name="grade" column="grade" type="string"/>
   </class>

</hibernate-mapping>

Code-2.31: Student.hbm.xml

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1. Modify the Main.java of the HibernateHelloWorld2 project as shown in Code-2.41 below. The code fragments that need to be changed are high-lighted in bold and blue-colored font. Please make sure you are modifying the Main.java of the HibernateHelloWorld2 project not HibernateHelloWorld project. (It is very easy to make this mistake.)

import org.hibernate.*;
import org.hibernate.cfg.Configuration;

public class Main {

    public static void main(String[] args) {

        // Set up database tables
        HibernateUtil.droptable("drop table Person");
        HibernateUtil.droptable("drop table Student");
        HibernateUtil.setup("create table Person ( id int, cname VARCHAR(20))");
        HibernateUtil.setup("create table Student ( id int, schoolname VARCHAR(30), grade VARCHAR(5))");

        // Create SessionFactory and Session object
        SessionFactory sessions = new Configuration().configure().buildSessionFactory();
        Session session = sessions.openSession();

        // Perform life-cycle operations under a transaction
        Transaction tx = null;
        try {
            tx = session.beginTransaction();

            // Create a Person object and save it
            Person p1 = new Person();
            p1.setName("Sang Shin");
            session.save(p1);

            // Create another Person object and save it.
            Person p2 = new Person();
            p2.setName("Young Shin");
            session.save(p2);

            // Retrieve the person objects
            Person person = (Person)session. get(Person.class, p1.getId());
            System.out.println("First person retrieved = " + person.getName());
            person = (Person)session.get(Person.class, p2.getId());
            System.out.println("Second person retrieved = " + person.getName());

            // Create a Student object and save it
            Student s1 = new Student();
            s1.setSchool("Lexington High School");
            s1.setGrade("A");
            session.save(s1);

            // Retrieve the Student objects
            Student student = (Student)session. get(Student.class, s1.getId());
            System.out.println("First student retrieved = " + student.getId() + ", " +
                               "School attending = " + student.getSchool() + ", " +
                               "Grade = " + student.getGrade());

            tx.commit();
            tx = null;
        } catch ( HibernateException e ) {
            if ( tx != null ) tx.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }

        // Display tables
        HibernateUtil.checkData("select * from Person");
        HibernateUtil.checkData("select * from Student");

    }

}

Code-2.41: Main.java

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1. Modify hibernate.cfg.xml file as shown in Code-2.52 below. The code fragment that needs to be added is highlighted in blue-colored and bold font.

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        
        <property name="connection.driver_class">org.apache.derby.jdbc.ClientDriver</property>
        <property name="connection.url">jdbc:derby://localhost:1527/mydatabase</property>
        <property name="connection.username">app</property>
        <property name="connection.password">app</property>

        
        <property name="connection.pool_size">1</property>

        
        <property name="dialect">org.hibernate.dialect.DerbyDialect</property>

        
        <property name="show_sql">true</property>

        
        <mapping resource="Person.hbm.xml"/>
        <mapping resource="Student.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

Code-2.52: Modified hibernate.cfg.xml file

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1. Right click HibernateHelloWorld2 project and select Run Project.
2. Observe the result in the Output window of the IDE. (Figure-2.61 below)

Figure-2.61: Result

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In this step, you are going to set the flag in the hibernate.cfg.xml file to display the SQL commands that are being sent by the Hibernate framework. This is a useful debugging feature.

1. Change the "show_sql" property of the <session-factory> element of the hibernate.cfg.xml file to true (from false) as shown in Figure-2.71 below.

Figure-2.71: Set "show_sql" property to true

2. Right-click HibernateHelloWorld2 project and select Run Project.
3. Observe the SQL commands that are being sent by the Hibernate. (Figure-2.72 below)

Figure-2.72: SQL commands

Solution: This exercise up to this point is provided as a ready-to-open-and-run NetBeans project as part of hands-on lab zip file. You can find it as <LAB_UNZIPPED_DIRECTORY>/hibernatestepbystep/samples/HibernateHelloWorld2. You will have to add Hibernate library files and client driver once you opened the project as described in Exercise 1.

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In this exercise, you are going to configure Javadoc of the Hibernate so that you can display context sensitive Java documentation on Hibernate classes. You do this just once meaning once it is configured, Javadoc of Hibernate classes can be displayed for all the other and future Hibernate projects.

1. Select Tools from the top-level menu and select Libraries. (Figure-3.10 below)

Figure-3.10: Select Java Platform Manager

2. Configure Javadoc for the HibernateCore library.

Select HibernateCore under Libraries on the left.
Select Javadoc tab window.
Click Add ZIP/Folder button. (Figure-3.11 below)

Figure-3.11: Add ZIP/Folder of the Hibernate Javadoc

Browse down to <LAB_UNZIPPED_DIRECTORY>/hibernatestepbystep/hibernatedoc directory
Select api and click Add ZIP/Folder button. (Figure-3.12 below)

Figure-3.12: Add api directory

Click OK to close the Library Manager dialog box. (Figure-3.13 below)

Figure-3.13: Close Java Platform Manager

1. Double-click Main.java to open it in the editor window.
2. Move the cursor on the Session and right click on it.
3. Select Show Javadoc. (Figure-3.21 below)

Figure-3.21: Select Show Javadoc on Session

4. Observe the Javadoc of the Session interface gets displayed in the browser. (Figure-3.22 below)
5. Please spend some time browsing various methods supported by Session interface.

Figure-3.22: Javadoc of Session interface

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In this exercise, you have learned how to display Javadoc of Hibernate classes in a context-sensitive manner.

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1. The homework is to create your own Hibernate project called HibernateMyHobby. You are welcome to create a new project from scratch as you've done in Exercise 1 or you can copy HibernateHelloWorld or HibernateHelloWorld2 project as you've done in Exercise 2 above.

The Hibernate project has the following POJO class.

Hobby class with the following fields

int myHobbyId
String hobby
int yearIstartedThisHobby

Create a database table called, hobbytable either manually or programmatically using HibernateUtil.setup() utility method as is done in the HibernateHelloWorld project.
In the Main.java, create a few instances of Hobby objects instances and save them to the database tables.

2. This is an optional exercise. Rebuild the project by using MySQL or HSQL. You can create a new project called HibernateMyHobbyMySQL or HibernateMyHobbyHSQL by copying HibernateMyHobby project. You can download MySQL and HSQL from the following sites.

MySQL (download for Windows) - optional
HSQLDB (download)

3. Send the following files to j2eehomeworks@sun.com with Subject as J2EEHomework-hibernatestepbystep.

Zip file of the the HibernateMyHobby NetBeans project. (Someone else should be able to open and run it as a NetBeans project.) You can use your favorite zip utility or you can use "jar" utility that comes with JDK as following.

cd <parent directory that contains HibernateMyHobby directory> (assuming you named your project as HibernateMyHobby)
jar cvf HibernateMyHobby.zip HibernateMyHobby (HibernateMyHobby should contain nbproject directory)

Captured output screen - name it as J2EEHomework-hibernatestepbystep.gif orJ2EEHomework-hibernatestepbystep.jpg (or J2EEHomework-hibernatestepbystep.<whatver graphics format>)

Any screen capture that shows that your program is working is good enough.

If you decide to use different IDE other than NetBeans, the zip file should contain all the files that are needed for rebuilding the project - war file with necessary source files is OK.

Building Hibernate Application Step By Step

Software Needed

Change Log

Things to be done (by Sang Shin)

Lab Exercises

Exercise 0: Start Derby Database server and Create "mydatabase" database

(0.1) Start Java DB (code-named as Derby) database server (if it has not been started already)

(0.2) Create a database of your own called "mydatabase" (if it has not been created already)

(0.3) Install Hibernate NetBeans Plug-in

Exercise 1: Build "HelloWorld" Hibernate application

(1.1) Write POJO classes

(1.2) Write Hibernate mapping files for the POJO classes.

(1.3) Write a Hibernate configuration file

(1.4) Write Main.java and HibernateUtil.java

(1.5) Add Hibernate library and Java DB driver

(1.6) Add log4j.properties file

(1.7) Build and run the application

(1.8) Verify the database

Summary

Exercise 2: Build "HibernateHelloWorld2" application

(2.1) Create "HibernateHelloWorld2" project by copying the "HibernateHelloWorld" project

(2.2) Add a new POJO class

(2.3) Write new mapping file, Student.hbm.xml, for the Student class

(2.4) Modify Main.java

(2.5) Modify hibernate.cfg.xml file

(2.6) Build and run the application

(2.7) Observe the SQL commands

Summary

Exercise 3: Configuring Hibernate JavaDoc

(3.1) Configure Hibernate Javadoc directory to the NetBeans IDE

(3.2) Display Javadoc of the Session Hibernate interface in a context-sensitive manner

Summary

Homework exercise (for people who are taking Sang Shin's "Java EE Programming online course")