Enabling Your Java Classes

The Employee model uses three classes:

• Employee class has a name attribute and privately owned PhoneNumber and Address relationships.

• PhoneNumber class has attributes describing the phone number information and a relationship that describes the owner of the PhoneNumber.

• Address class has attributes describing the employee's mailing address.

You must enable the Employee, PhoneNumber, and Address classes (provided in the examples.session.threetier.model package) for this tutorial, as "Generating the Class Definitions" describes.

Table B–5 shows how the classes relate to the database tables.

Table B-5 Employee Classes and Database Tables

Column	Class Attribute	Database Type	Java Type
EMPLOYEE	Employee
EMP_ID	id	NUMERIC(15)	BigDecimal
NAME	name	CHAR(40)	String
ADDRESS_ID	address	NUMERIC(15)	Address
not applicable	phoneNumbers	not applicable	Vector
ADDRESS	Address
ADDRESS_ID	id	NUMERIC(15)	BigDecimal
COUNTRY	country	VARCHAR(80)	String
STREET	street	VARCHAR(80)	String
CITY	city	VARCHAR(80)	String
PROVINCE	province	VARCHAR(80)	String
P_CODE	postalCode	VARCHAR(20)	String
PHONE	PhoneNumber
AREA_CODE	areaCode	CHAR(3)	String
P_NUMBER	number	CHAR(7)	String
EMP_ID	owner	NUMERIC(15)	Employee
TYPE	type	VARCHAR(15)	String

Note: Supplying each of the class members in OracleAS TopLink-enabled classes with accessor methods is good programming practice. This tutorial provides the get and set methods for each attribute. For example, the Employee class should have an addPhoneNumber() method to allow a new PhoneNumber to store a reference to its parent.

Example B-1 Accessor Method

The following code example illustrates providing accessor methods.

// addPhoneNumber method of the Employee class allows the phoneNumber to set a reference to the Employee that owns it.
public void addPhoneNumber(PhoneNumber phoneNumber)
{
    getPhoneNumbers().addElement(phoneNumber);
    phoneNumber.setOwner(this);
}

Generating the Class Definitions

You must generate an OracleAS TopLink descriptor for each Java class in the project.

To create descriptors from the class definition file:

1. From the Navigator pane, click the Employee project.

2. 
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   Click the Add or Refresh Classes button or choose Selected > Add or Refresh Classes from the menu. The Select Classes dialog box appears.

   You can also create descriptors by right-clicking on the project in the Navigator pane and selecting Add or Refresh Classes from the pop-up menu.

   Figure B-9 Select Classes

   
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3. 
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   Locate the examples.sessions.threetier.model package. Click the plus sign to expand that package (or double-click the name to expand the package).

   Figure B-10 Demo Classes

   
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4. 
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   Highlight the Address class and click the button. OracleAS TopLink copies the Address class to the Selected Classes pane.

   Figure B-11 Selected Class

   
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5. 
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   Repeat Step 4 for Employee and PhoneNumber classes in that package. (Or, highlight both classes using Shift+click or Ctrl+click as necessary, and click once to import all the remaining classes.)

6. Click OK to import the classes. OracleAS TopLink creates a descriptor for each class and an unmapped mapping for each attribute. The descriptors and their attributes appear in the Navigator pane.

   
   

   Note: If an error occurs, check that the given classes are included in the classpath and that JDK has been installed correctly.

   
   

   Figure B-12 OracleAS TopLink Mapping Workbench with Employee Project

   
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   Figure B-12 identifies the following user-interface elements:

   1. Package

   2. Class/descriptors

7. 
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   Save your changes. Click Save or choose File > Save from the menu.