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Chapter 8 Examples
Download all Chapter 8 code View code examples 8.1 to 8.12 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 Example 8.1 Implementing Business Delegate Pattern – ResourceDelegate
// imports
...
public class ResourceDelegate {
// Remote reference for Session Facade
private ResourceSession session;
// Class for Session Facade's Home object
private static final Class homeClazz =
corepatterns.apps.psa.ejb.ResourceSessionHome.class;
// Default Constructor. Looks up home and connects
// to session by creating a new one
public ResourceDelegate() throws ResourceException {
try {
ResourceSessionHome home = (ResourceSessionHome)
ServiceLocator.getInstance().getHome(
"Resource", homeClazz);
session = home.create();
} catch(ServiceLocatorException ex) {
// Translate Service Locator exception into
// application exception
throw new ResourceException(...);
} catch(CreateException ex) {
// Translate the Session create exception into
// application exception
throw new ResourceException(...);
} catch(RemoteException ex) {
// Translate the Remote exception into
// application exception
throw new ResourceException(...);
}
}
// Constructor that accepts an ID (Handle id) and
// reconnects to the prior session bean instead
// of creating a new one
public BusinessDelegate(String id)
throws ResourceException {
super();
reconnect(id);
}
// Returns a String ID the client can use at a
// later time to reconnect to the session bean
public String getID() {
try {
return ServiceLocator.getId(session);
} catch (Exception e) {
// Throw an application exception
}
}
// method to reconnect using String ID
public void reconnect(String id)
throws ResourceException {
try {
session = (ResourceSession)
ServiceLocator.getService(id);
} catch (RemoteException ex) {
// Translate the Remote exception into
// application exception
throw new ResourceException(...);
}
}
// The following are the business methods
// proxied to the Session Facade. If any service
// exception is encountered, these methods convert
// them into application exceptions such as
// ResourceException, SkillSetException, and so
// forth.
public ResourceVO setCurrentResource(
String resourceId)
throws ResourceException {
try {
return session.setCurrentResource(resourceId);
} catch (RemoteException ex) {
// Translate the service exception into
// application exception
throw new ResourceException(...);
}
}
public ResourceVO getResourceDetails()
throws ResourceException {
try {
return session.getResourceDetails();
} catch(RemoteException ex) {
// Translate the service exception into
// application exception
throw new ResourceException(...);
}
}
public void setResourceDetails(ResourceVO vo)
throws ResourceException {
try {
session.setResourceDetails(vo);
} catch(RemoteException ex) {
throw new ResourceException(...);
}
}
public void addNewResource(ResourceVO vo)
throws ResourceException {
try {
session.addResource(vo);
} catch(RemoteException ex) {
throw new ResourceException(...);
}
}
// all other proxy method to session bean
...
}
Example 8.2 Remote Interface for ResourceSession
// imports
...
public interface ResourceSession extends EJBObject {
public ResourceVO setCurrentResource(
String resourceId) throws
RemoteException, ResourceException;
public ResourceVO getResourceDetails()
throws RemoteException, ResourceException;
public void setResourceDetails(ResourceVO resource)
throws RemoteException, ResourceException;
public void addResource(ResourceVO resource)
throws RemoteException, ResourceException;
public void removeResource()
throws RemoteException, ResourceException;
// methods for managing blockout time by the
// resource
public void addBlockoutTime(Collection blockoutTime)
throws RemoteException, BlockoutTimeException;
public void updateBlockoutTime(
Collection blockoutTime)
throws RemoteException, BlockoutTimeException;
public void removeBlockoutTime(
Collection blockoutTime)
throws RemoteException, BlockoutTimeException;
public void removeAllBlockoutTime()
throws RemoteException, BlockoutTimeException;
// methods for resource skillsets time by the
//resource
public void addSkillSets(Collection skillSet)
throws RemoteException, SkillSetException;
public void updateSkillSets(Collection skillSet)
throws RemoteException, SkillSetException;
public void removeSkillSet(Collection skillSet)
throws RemoteException, SkillSetException;
...
}
Example 8.3 Implementing the Value Object Pattern – Value Object Class
// Value Object to hold the details for Project
public class ProjectVO implements java.io.Serializable {
public String projectId;
public String projectName;
public String managerId;
public String customerId;
public Date startDate;
public Date endDate;
public boolean started;
public boolean completed;
public boolean accepted;
public Date acceptedDate;
public String projectDescription;
public String projectStatus;
// Value object constructors...
}
Example 8.4 Implementing the Value Object Pattern – Entity Bean Class
...
public class ProjectEntity implements EntityBean {
private EntityContext context;
public String projectId;
public String projectName;
public String managerId;
public String customerId;
public Date startDate;
public Date endDate;
public boolean started;
public boolean completed;
public boolean accepted;
public Date acceptedDate;
public String projectDescription;
public String projectStatus;
private boolean closed;
// other attributes...
private ArrayList commitments;
...
// Method to get value object for Project data
public ProjectVO getProjectData() {
return createProjectVO();
}
// method to create a new value object and
// copy data from entity bean into the value
// object
private ProjectVO createProjectVO() {
ProjectVO proj = new ProjectVO();
proj.projectId = projectId;
proj.projectName = projectName;
proj.managerId = managerId;
proj.startDate = startDate;
proj.endDate = endDate;
proj.customerId = customerId;
proj.projectDescription = projectDescription;
proj.projectStatus = projectStatus;
proj.started = started;
proj.completed = completed;
proj.accepted = accepted;
proj.closed = closed;
return proj;
}
...
}
Example 8.5 Implementing Updatable Value Objects Strategy
...
public class ProjectEntity implements EntityBean {
private EntityContext context;
...
// attributes and other methods as in Example 8.4
...
// method to set entity values with a value object
public void setProjectData(ProjectVO updatedProj) {
mergeProjectData(updatedProj);
}
// method to merge values from the value object into
// the entity bean attributes
private void mergeProjectData(ProjectVO updatedProj) {
// version control check may be necessary here
// before merging changes in order to
// prevent losing updates by other clients
projectId = updatedProj.projectId;
projectName = updatedProj.projectName;
managerId = updatedProj.managerId;
startDate = updatedProj.startDate;
endDate = updatedProj.endDate;
customerId = updatedProj.customerId;
projectDescription =
updatedProj.projectDescription;
projectStatus = updatedProj.projectStatus;
started = updatedProj.started;
completed = updatedProj.completed;
accepted = updatedProj.accepted;
closed = updatedProj.closed;
}
...
}
Example 8.6 Multiple Value Objects Strategy – ResourceVO
// ResourceVO: This class holds basic information
// about the resource
public class ResourceVO implements
java.io.Serializable {
public String resourceId;
public String lastName;
public String firstName;
public String department;
public String grade;
...
}
Example 8.7 Multiple Value Objects Strategy – ResourceDetailsVO
// ResourceDetailsVO This class holds detailed
// information about resource
public class ResourceDetailsVO {
public String resourceId;
public String lastName;
public String firstName;
public String department;
public String grade;
// other data...
public Collection commitments;
public Collection blockoutTimes;
public Collection skillSets;
}
Example 8.8 Multiple Value Objects Strategy – Resource Entity Bean
// imports
...
public class ResourceEntity implements EntityBean {
// entity bean attributes
...
// entity bean business methods
...
// Multiple Value Object method : Get ResourceVO
public ResourceVO getResourceData() {
// create new ResourceVO instance and copy
// attribute values from entity bean into VO
...
return createResourceVO();
}
// Multiple Value Object method : Get
// ResourceDetailsVO
public ResourceDetailsVO getResourceDetailsData() {
// create new ResourceDetailsVO instance and copy
// attribute values from entity bean into VO
...
return createResourceDetailsVO();
}
// other entity bean methods
...
}
Example 8.9 Multiple Value Objects Strategy – Entity Bean Client
...
private ResourceEntity resourceEntity;
private static final Class homeClazz =
corepatterns.apps.psa.ejb.ResourceEntityHome.class;
...
try {
ResourceEntityHome home =
(ResourceEntityHome)
ServiceLocator.getInstance().getHome(
"Resource", homeClazz);
resourceEntity = home.findByPrimaryKey(
resourceId);
} catch(ServiceLocatorException ex) {
// Translate Service Locator exception into
// application exception
throw new ResourceException(...);
} catch(FinderException ex) {
// Translate the entity bean finder exception into
// application exception
throw new ResourceException(...);
} catch(RemoteException ex) {
// Translate the Remote exception into
// application exception
throw new ResourceException(...);
}
...
// retrieve basic Resource data
ResourceVO vo = resourceEntity.getResourceData();
...
// retrieve detailed Resource data
ResourceDetailsVO =
resourceEntity.getResourceDetailsData();
...
Example 8.10 Entity Inherits Value Object Strategy – Value Object Class
// This is the value object class inherited by
// the entity bean
public class ContactVO
implements java.io.Serializable {
// public members
public String firstName;
public String lastName;
public String address;
// default constructor
public ContactVO() {}
// constructor accepting all values
public ContactVO(String firstName,
String lastName, String address){
init(firstName, lastName, address);
}
// constructor to create a new VO based
// using an existing VO instance
public ContactVO(ContactVO contact) {
init (contact.firstName,
contact.lastName, contact.address);
}
// method to set all the values
public void init(String firstName, String
lastName, String address) {
this.firstName = firstName;
this.lastName = lastName;
this.address = address;
}
// create a new value object
public ContactVO getData() {
return new ContactVO(this);
}
}
Example 8.11 Entity Inherits Value Object Strategy – Entity Bean Class
public class ContactEntity extends ContactVO implements
javax.ejb.EntityBean {
...
// the client calls the getData method
// on the ContactEntity bean instance.
// getData() is inherited from the value object
// and returns the ContactVO value object
...
}
Example 8.12 Value Object Factory Strategy – Value Objects and Interfaces
public interface Contact
extends java.io.Serializable {
public String getFirstName();
public String getLastName();
public String getContactAddress();
public void setFirstName(String firstName);
public void setLastName(String lastName);
public void setContactAddress(String address);
}
public class ContactVO implements Contact {
// member attributes
public String firstName;
public String lastName;
public String contactAddress;
// implement get and set methods per the
// Contact interface here.
...
}
public interface Customer
extends java.io.Serializable {
public String getCustomerName();
public String getCustomerAddress();
public void setCustomerName(String customerName);
public void setCustomerAddress(String
customerAddress);
}
public class CustomerVO implements Customer {
public String customerName;
public String customerAddress;
// implement get and set methods per the
// Customer interface here.
...
}
public class CustomerContactVO implements Customer,
Contact {
public String firstName;
public String lastName;
public String contactAddress;
public String customerName;
public String customerAddress;
// implement get and set methods per the
// Customer and Contact interfaces here.
...
}
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