Using VisualAge for Java Enterprise Version 2 to Develop CORBA and EJB Applications

Moving to Enterprise JavaBeans 187

17.3.1 Adding Behavior to Your EJB

When you create an EJB in the EJB development environment, a set of

required methods for the bean is automatically created. You can modify these

methods and add new remote (business) and home methods of your own.

Adding methods in the EJB development environment is similar to adding

methods elsewhere in VisualAge for Java. Once you have created remote

(business) methods or home methods for your classes and interfaces, you

can promote the methods to the remote and home interfaces from the Bean

class without editing the remote and home interfaces directly.

Follow these steps to add a new method:

1. In the Types pane of the EJBs page, select the class or interface to which

you want to add a method.

2. Click mouse button 2, then select Add Method from the pop-up menu.

The Add Method SmartGuide appears.

3. Follow the SmartGuide instructions on creating a new method.

4. Click Finish to create and compile the new method.

If you want to remove a remote method from the remote interface, select the

method and then select Methods-> Remove From ->EJB Remote Interface.

If you want to remove a home method from the home interface, select the

method and then select Methods-> Remove From ->EJB Home Interface.

Before we add methods to our EJB, we are going to define some properties

that are used later on. We add the following properties to the

EmployeeIDBean class:

private Connection _connection;

private static String _jdbcURL = "jdbc:db2:sample";

private static String _jdbcDriverName = "COM.ibm.db2.jdbc.app.DB2Driver";

public String userid;

private Statement _statement;

and an import statement:

import java.sql.*;

In our EmployeeID bean, we are going to add two methods:

• getConnection()

This method loads the JDBC driver and returns a connection

188 Using VisualAge for Java Enterprise Version 2 to Develop CORBA and EJB Applications

private Connection getConnection()

{

System.out.println("getConnection ");

if (_connection == null)

{

try

{

Class.forName(_jdbcDriverName).newInstance();

_connection = DriverManager.getConnection(_jdbcURL);

}

catch(Exception e)

{

System.out.println("getConnection error ");

e.printStackTrace();

}

}

return _connection;

}

• authenticate(String)

This method compares the user entered password against the first name

found in the database table corresponding to the serial number. If they

match, the user has been authenticated.

public boolean authenticate(String password) throws

java.rmi.RemoteException

{

return password.equals(userFirstname);

}

If you want to promote a remote method to the remote interface, select the

method and then select Methods->Add to->EJB Remote Interface.

If you want to promote a home method to the home interface, select the

method and then select Methods->Add to->EJB Home Interface.

Typically, to add a method in a development environment that uses interfaces

and implementations, you would add the method first to the interface, and

then to the implementation class. However, the EJB development model is

slightly different. If you browse the EmployeeID bean, you will notice that it

does not implement the EmployeeID interface. The EmployeeID interface is a

generated class, and if you add method signatures to it, they will be

overwritten.

Moving to Enterprise JavaBeans 189

So, add the method to the interface, using the Add To->EJB Remote

Interface menu items (see Figure 82).

Figure 82. Adding Method to EJB Interface

The EmployeeID interface now contains an authenticate() method.

Now we need to modify some of the generated methods to add additional

behavior:

1. ejbActivate()

We just request the connection by calling the added method

getConnection.

public void ejbActivate() throws java.rmi.RemoteException {

getConnection();

}

2. ejbCreate(EmployeeIDKey)

public /**@EJBHome*/ EmployeeIDKey ejbCreate(EmployeeIDKey key) throws

javax.ejb.CreateException {

190 Using VisualAge for Java Enterprise Version 2 to Develop CORBA and EJB Applications

primaryKey=key.primaryKey;

return key;

}

3. ejbFindByPrimaryKey(EmployeeIDKey)

public /**@EJBHome*/ EmployeeIDKey ejbFindByPrimaryKey (EmployeeIDKey key) throws

javax.ejb.FinderException, RemoteException {

Statement statement = null;

ResultSet rs = null;

System.out.println("ejbFindByPrimaryKey ");

try

{

ejbActivate();

String sql = "SELECT FIRSTNME FROM EMPLOYEE WHERE EMPNO = ’"+key.primaryKey+"’";

statement = getConnection().createStatement();

rs = statement.executeQuery(sql);

if (rs.next()){

//System.out.println("firstname is:" + rs.getString("FIRSTNME").trim());

userFirstname = rs.getString("FIRSTNME").trim();

System.out.println("firstname is:" + userFirstname);

return new EmployeeIDKey(key.primaryKey);

}

else

throw new FinderException("Employee ID not found: "+key.primaryKey);

}

catch(SQLException e)

{

throw new RemoteException(e.getMessage(), e);

}

finally

{

try

{

statement.close();

}

catch(Exception e){

}

}

}

4. ejbPassivate

public void ejbPassivate() throws java.rmi.RemoteException {

System.out.println("ejbPassivate ");

try

{

getConnection().close();

}

catch(Exception e)

{

e.printStackTrace();

}

finally

{

_connection = null;

}

}