Hibernate Class Generation Using hbm2java

A Simple Class Generation Example

Let's start with a very simple example. Suppose we want to map a simple table called BOOK, as described here:

Column      |         Type          | Modifiers

------------+-----------------------+-----------

 BOOK_ID    | character(32)         | not null

 BOOK_TITLE | character varying(80) | not null

 BOOK_ISBN  | character varying(20) | not null

To generate this class, we could use the following Hibernate mapping file. Note how meta-attributes can be used to add comments or fine-tune class generation.

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC

    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">



<hibernate-mapping>



    <class name="Book" table="BOOK">

        <meta attribute="class-description">

            A Book business object.

            @author Duke

        </meta>

        <id name="id" type="string" unsaved-value="null" >

            <column name="BOOK_ID" sql-type="char(32)" not-null="true"/>

            <generator class="uuid.hex"/>

        </id>



        <property column="BOOK_NAME" name="name"/>

        <property column="BOOK_ISBN" name="isbn">

            <meta attribute="field-description"/>

            The unique ISBN code for this book.

            </meta>

        </property>

    </class>



</hibernate-mapping>

Using this mapping file, the hbm2java will generate a class that looks something like this:

/**

 * A Book business object.

 * @author Duke

 */

public class Book {



    private String id;

    private String name;

    private String isbn;



    public Book() {

    }



    public String getId() {

        return id;

    }



    private void setId(String id) {

        this.id = id;

    }



    public String getName() {

        return name;

    }



    public void setName(String name) {

        this.name = name;

    }



    /**

     * The unique ISBN code for this book.

     */

    public String getIsbn() {

        return isbn;

    }



    public void setIsbn(String isbn) {

        this.isbn = isbn;

    }

}