Java Reference
In-Depth Information
14.3.1
Constructing the user information entity bean
The single entity bean—the user information EJB —will provide the persistence
mechanism for the user data. Remember from the problem description that this
EJB counts the number of user logins and provides permissions for the user.
Every entity bean needs a primary key, which references the EJB 's row in the data-
base. For the user information EJB , the primary key is a user name value.
The home interface
Listing 14.1 is the home interface for the entity bean. The home interface declares
methods for creating and locating this type of EJB . (Again, for more information
about using and constructing EJB s, go to http://www.javasoft.com.)
Listing 14.1
UserInfoHome.java
package jmxbook.ch14;
import javax.ejb.*;
import java.rmi.*;
import java.util.*;
public interface UserInfoHome extends EJBHome
{
public UserInfo create( String userName )
throws CreateException, RemoteException;
public UserInfo findByPrimaryKey( String userName )
throws FinderException, RemoteException;
}
The home interface provides a create() method for creating a new instance of
the EJB and a findByPrimaryKey() method for locating an existing instance.
Because the EJB 's primary key is a user name, it is passed in to both the create()
and findByPrimaryKey() methods.
The remote interface
Listing 14.2 shows the remote interface for the entity bean. The remote interface
declares the methods an EJB client uses to interact with an entity bean. The EJB
create() and findByPrimaryKey() methods of the home interface return an
instance of the EJB 's remote interface. The remote interface declares the busi-
ness methods of the application.
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