BMP EJB Classes

The current release includes a beta release of the bean managed persistence EJB generator.

Overview

Bean Managed Persistence enterprise java beans can require a lot of coding. The JDBC Wizard can use database tables or views. In order to generate BMP EJB's a few steps must be taken using the wizard:

1. Create the bean
2. Select the columns you would like to select, insert and update
3. Create finders, if any. The wizard automatically generates findByPrimaryKey(). For additional finder methods (eg findAll(), findByRegion(String theRegion)) the Wizard must be used to specify part of the SQL, and any parameters the finders need.
4. Select the create() methods to generate. And if the remove() method should delete a database record, or just thorw an exception.

Primary Keys

If the database object does not have a primary key defined, please follow these steps:

1. Select the column object which is to be a primary key, or part of a composite primary key
2. Check the Primary Key checkbox
3. Press Save

Creating A BMP EJB

By drilling down the treeview control, we can reach the "BMP EJB Classes" node below the database table or view of our choice. See below.

• The EJB Name is used as the name for the bean's remote interface.
• The package is the java package of all the bean's support java files.
• The manifest name is the name given to the bean in the xml manifest file. The bean name should be unique within the Wizard project file. When generating EJB's the wizzard generates one manifest with descriptions of all the EJB's generated.

When the create button is pressed, the user is navigated to the next set of dialogs.

Configuring BMP EJB's

The BMP EJB Classes tab (shown below), displays java class and manifest information the wizard will generate.

• The remote interface is used by the client to represent an instance of a bean. The interface includes methods to get and set bean properties. The remote interface extends EJBObject, and so also has methods to get the primary key, get the handle, and remove to the bean.
• The bean package is the name of the java package all generated files should use.
• The implementation class is the EJB class. Contained within are all the methods necessary to implement the EJB.
• The home interface (or bean factory), is used by the client to create and find bean instances. This interface extends EJBHome, and so also has methods to remove a bean instance.
• The key class is used to hold a bean's primary key valur. The key class is a java type for simple keys. The wizard generates classes to represent a composite key's values.
• Key class is the class used to represent the primary key. This is usually a Java type. Should the key be composite, the wizard generates an appropriate primary key class.
• DAO key class is used by the implementation class. This class is the data access object for the bean's key. This class contains JDBC code to find primary keys behind the scenes.
• DAO data class is used to hold all of a bean's property values.
• DAO class contains JDBC code to manage one bean instance: findByPrimaryKey, store, create, remove.
• The name in manifest, is the name used for the bean in the generated manifest file. The name should be unique within a JDBC Wizard project.
• Javadoc for each class can be edited or created . If no comments are present, default comments are generated when the code is generated.

Configuring Columns

The columns tab is used to configure the bean's individual columns, and how they map to the underlying database. The bean must have select and insert access to the primary key column(s).

The columns property editor pops up when an entry in the table is double clicked.

• The column name is the database table, or view, column name.
• The property name is the name of the bean property which represents this column.
• The transaction to use on the get and set methods is set here.
• The access combo is used to determine what the bean can do to the database: insert and/or update and/or select the column value.
• The property type is the java type the property should have.
• The get/set op. controls the JDBC Resultset and PreparedStatement get and set methods to use for this column.
• The set NULL JDBC type controls what constant to use when calling setNull() on a PreparedStatement object.

Configuring Finders

The finders tab allows bean finders to be created, edited and removed.

To create a new finder, press the new button.

• SQL is entered in the textarea control. Enter question mark ? characters to denote parameters to the SQL statement.
• The buttons are as follows:

  Create a new parameter on the end of the list
  Create a new parameter below the currently selected parameter
  Create a new parameter above the currently selected parameter
  Edit the currently selected parameter
  Delete the currently selected parameter

Below is a sample EJB finder parameter dialog:

• Parameter Name is used to name the parameter in the finder method call.
• Set Fields From quickly sets this dialog's controls to the values of one of the columns previously configured.
• Precision is the total number of digits for numbers and characters for strings.
• Scale is only useful for decimal numbers. It specifies how many decimal digits the number can have.
• Java Type is the java type of the parameter.
• Get/Set Op. is the PreparedStatement get and set method call to use.
• Set NULL JDBC Type  controls what constant to use when calling setNull() on a PreparedStatement object.

Configuring Create Methods

The wizard allows two types of ejb create methods to be generated. For example:

public Person create(PersonDAOData thePersonDAOData)
public Person create(String theEmail, String theFirstName, String theLastName, String theTitle) 

The PersonDAOData class is also generated by the wizard. It is used to hold a bean instance's values.

public class PersonDAOData implements java.io.Serializable
{
   protected Date myDateAdded;
   protected String myEmail;
   protected String myFirstName;
   protected String myLastName;
   protected String myTitle;
   public PersonDAOData() 
   public PersonDAOData(PersonDAOData theToCopy) 
   public void clearProperties() 
   public Date getDateAdded() 
   public String getEmail() 
   public String getFirstName() 
   public String getLastName() 
   public String getTitle() 
   public void setDateAdded(Date theDateAdded) 
   public void setEmail(String theEmail) throws NullPointerException
   public void setFirstName(String theFirstName) 
   public void setLastName(String theLastName) 
   public void setTitle(String theTitle) 
}

The tab (shown above) has the following settings:

• Generate create(DAO Data Class) is used to generate a create method which uses a DAO data class to hold the bean values.
• Generate create(Bean Property1, 2, ...) is used to generate a method which uses one parameter per database column.

Configuring The Remove Method

• Remove can be made to delete a record from the database, or to throw and exception if remove is called.

Generating Java Code

The wizard can generate java code, when one or more beans have been created in the wizard.

More information on generating and using the EJB source code can be found here.