Raible's Wiki: CreateManager

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__Part II:__ [Creating new Managers|CreateManager] - A HowTo for creating [Business Delegates|http://java.sun.com/blueprints/corej2eepatterns/Patterns/BusinessDelegate.html] that talk to the database tier (DAOs) and the web tier (Struts Actions).

__Part II:__ [Creating new Managers|CreateManager] - A HowTo for creating Business Facades that talk to the database tier (DAOs) and handle transaction management.

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;:''This tutorial depends on __Part I:__ [Creating new DAOs and Objects in AppFuse|CreateDAO].''

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This tutorial will show you how to create a Business Delegate class (and a JUnit) to talk to the [DAO we created in Part I|CreateDAO] of this tutorial.

This tutorial will show you how to create a Business Facade class (and a JUnit Test) to talk to the [DAO we created in Part I|CreateDAO].

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In the context of [AppFuse], this is called a Manager class. It's main responsibility is converting backend data (POJOs) into front-end data (Struts ActionForms). The main reason I even use Managers, rather than just calling the DAOs directly is testability. It's nice to be able to populate a Form manually (in the test) and call the DAO to persist it, and verify the database gets the proper results. The [Business Delegate|http://java.sun.com/blueprints/corej2eepatterns/Patterns/BusinessDelegate.html] pattern from Sun says that these objects are usefull for de-coupling your presentation layer from your database layer. Managers should also be where you put any business logic for your application.

In the context of [AppFuse], this is called a Manager class. Its main responsibility is to act as a bridge between the persistence (DAO) layer and the web layer. It's also useful for de-coupling your presentation layer from your database layer (i.e. for Swing apps). Managers should also be where you put any business logic for your application.

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Let's get started on creating a new ManagerTest and Manager in AppFuse's architecture.

Let's get started by creating a new ManagerTest and Manager in AppFuse's architecture.

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* [3] Run the ManagerTest

* [3] Configure Spring for this Manager and Transactions

* [4] Run the ManagerTest

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Since we're continuing from [Part I|CreateDAO], let's create a JUnit test for the PersonManager. Create PersonManagerTest in the test/web/**/service directory. We'll want to test the same basic methods (get, save, remove) that our DAO has. This may seem redundant (why all the tests!), but these tests are GREAT to have 6 months down the road. This class should extend [BaseManagerTestCase|http://raibledesigns.com/downloads/appfuse/api/org/appfuse/webapp/service/BaseManagerTestCase.java.html], which already exists in the ''service'' package. The parent class (BaseManagerTestCase) serves the same functionality as the BaseDaoTestCase - to load a properties file that has the same name as your *Test.class.

In [Part I|CreateDAO], we created a Person object and PersonDao - so let's continue developing this entity. First, let's create a JUnit test for the PersonManager. Create PersonManagerTest in the test/service/**/service directory. We'll want to test the same basic methods (get, save, remove) that our DAO has.

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;:%%(color: blue)''I usually copy (open → save as) an existing test (i.e. UserManagerTest.java) and find/replace [[Uu]ser with [[Pp]erson, or whatever the name of my object is.''%%

;:''This may seem redundant (why all the tests!), but these tests are GREAT to have 6 months down the road.''

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The code below is what we need for a basic JUnit test of our Managers. It created and destroys our PersonManager. The "conn" object is initialized (and obtains a connection) in the [BaseManagerTestCase|http://raibledesigns.com/downloads/appfuse/api/org/appfuse/webapp/service/BaseManagerTestCase.java.html] class.

This class should extend [BaseManagerTestCase|http://raibledesigns.com/downloads/appfuse/api/org/appfuse/service/BaseManagerTestCase.java.html], which already exists in the ''service'' package. The parent class (BaseManagerTestCase) serves similar functionality as the BaseDaoTestCase.

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{{{

package org.appfuse.webapp.service;

;:%%(color: blue)''I usually copy (open → save as) an existing test (i.e. UserManagerTest.java) and find/replace [[Uu]ser with [[Pp]erson, or whatever the name of my object is.''%%

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import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

The code below is what you need for a basic JUnit test of your Manager. Unlike the DaoTest, this test uses [jMock|http://jmock.org] to isolate the Manager from its dependencies and make it a ''true'' "unit" test. This can be very helpful because it allows you to test your business logic w/o worrying about other dependencies. The code below simply sets up the Manger and its dependencies (as Mocks) for testing.

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import org.appfuse.webapp.form.PersonForm;

[{Java2HtmlPlugin

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public class PersonManagerTest extends BaseManagerTestCase {

//~ Instance fields ========================================================

package org.appfuse.service;

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private PersonManager mgr = null;

private Log log = LogFactory.getLog(PersonManagerTest.class);

private PersonForm personForm;

import java.util.List;

import java.util.ArrayList;

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//~ Constructors ===========================================================

import org.appfuse.dao.PersonDao;

import org.appfuse.model.Person;

import org.appfuse.service.impl.PersonManagerImpl;

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public PersonManagerTest(String name) {

super(name);

}

import org.jmock.Mock;

import org.springframework.orm.ObjectRetrievalFailureException;

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//~ Methods ================================================================

public class PersonManagerTest extends BaseManagerTestCase {

private final String personId = "1";

private PersonManager personManager = new PersonManagerImpl();

private Mock personDao = null;

private Person person = null;

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mgr = new PersonManagerImpl(conn);

personDao = new Mock(PersonDao.class);

personManager.setPersonDao((PersonDao) personDao.proxy());

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mgr = null;

personManager = null;

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public static void main(String[] args) {

junit.textui.TestRunner.run(PersonManagerTest.class);

}

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}}}

Now that we have the JUnit framework down for this class, let's add the meat: the test methods to make sure everything works in our Manager. Here's a snippet from the [DAO Tutorial|CreateDAO] tutorial to help you understand what we're about to do.

}]

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Now that you have the skeleton done for this class, you need to add the meat: the test methods to make sure everything works. Here's a snippet from the [DAO Tutorial|CreateDAO] tutorial to help you understand what we're about to do.

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{{{

public void testGetPerson() throws Exception {

personForm = (PersonForm) mgr.getPerson("1");

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if (log.isDebugEnabled()) {

log.debug(personForm);

}

[{Java2HtmlPlugin

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assertTrue(personForm != null);

assertTrue(personForm.getFirstName() != null);

public void testGetPerson() throws Exception {

// set expected behavior on dao

personDao.expects(once()).method("getPerson")

.will(returnValue(new Person()));

person = personManager.getPerson(personId);

assertTrue(person != null);

personDao.verify();

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personForm = (PersonForm) mgr.getPerson("1");

personForm.setFirstName("Joe");

// set expected behavior on dao

personDao.expects(once()).method("savePerson")

.with(same(person)).isVoid();

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if (log.isDebugEnabled()) {

log.debug("saving person with updated firstName: " + personForm);

}

personManager.savePerson(person);

personDao.verify();

}

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personForm = (PersonForm) mgr.savePerson(personForm);

assertTrue(personForm.getFirstName().equals("Joe"));

}

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personForm = new PersonForm();

person = new Person();

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// call populate method in super class to populate test data

// from a properties file matching this class name

personForm = (PersonForm) populate(personForm);

// set required fields

person.setFirstName("firstName");

person.setLastName("lastName");

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personForm = (PersonForm) mgr.savePerson(personForm);

assertTrue(personForm.getLastName().equals("Raible"));

// set expected behavior on dao

personDao.expects(once()).method("savePerson")

.with(same(person)).isVoid();

personManager.savePerson(person);

personDao.verify();

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if (log.isDebugEnabled()) {

log.debug("removing person...");

}

// reset expectations

personDao.reset();

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mgr.removePerson(personForm);

personDao.expects(once()).method("removePerson").with(eq(new Long(personId)));

personManager.removePerson(personId);

personDao.verify();

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// reset expectations

personDao.reset();

// remove

Exception ex = new ObjectRetrievalFailureException(Person.class, person.getId());

personDao.expects(once()).method("removePerson").isVoid();

personDao.expects(once()).method("getPerson").will(throwException(ex));

personManager.removePerson(personId);

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personForm = (PersonForm) mgr.getPerson("1");

fail("Expected 'Exception' not thrown");

} catch (Exception e) {

if (log.isDebugEnabled()) {

log.debug(e);

}

assertTrue(e != null);

personManager.getPerson(personId);

fail("Person with identifier '" + personId + "' found in database");

} catch (ObjectRetrievalFailureException e) {

assertNotNull(e.getMessage());

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personDao.verify();

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}}}

This class won't compile at this point because we have not created our PersonManager nor the PersonManagerImpl. Unlike the DAO class, I'm not using a Factory pattern. Rather, I'm instantiating new Managers using:

{{{

Manager mgr = new ManagerImp(conn);

}}}

If I followed recommended patterns a bit more, I'd do:

{{{

Manager mgr = ManagerFactory.getInstance(conn, PersonManager.class);

}}}

I don't have any reason for ''not doing'' the factory pattern on Managers, I just simply haven't done it. I __am__ creating Interfaces for the Managers - in case I decide I need new ManagerImpls someday. Then it'd be easy to create a Factory and different implementations.

}]

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This class won't compile at this point because we have not created our PersonManager interface.

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First off, create a PersonManager.java interface in the src/web/**/service directory and specify the basic CRUD methods for any implementation classes. ''I've eliminated the JavaDocs in the class below for display purposes.''

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First off, create a PersonManager.java interface in the src/service/**/service directory and specify the basic CRUD methods for any implementation classes. ''I've eliminated the JavaDocs in the class below for display purposes.'' The ''setPersonDao()'' method is not used in most cases - its just exists so the PersonManagerTest can set the DAO on the interface.

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{{{

package org.appfuse.webapp.service;

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public interface PersonManager {

[{Java2HtmlPlugin

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public Object getPerson(String id) throws Exception;

package org.appfuse.service;

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public Object savePerson(Object person) throws Exception;

import org.appfuse.model.Person;

import org.appfuse.dao.PersonDao;

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public void removePerson(Object Person) throws Exception;

public interface PersonManager {

public void setPersonDao(PersonDao dao);

public Person getPerson(String id);

public void savePerson(Person person);

public void removePerson(String id);

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}}}

Now let's create a PersonManagerImpl class that implements the methods in PersonManager and uses [BeanUtils.copyProperties|http://jakarta.apache.org/commons/beanutils/api/org/apache/commons/beanutils/BeanUtils.html#copyProperties(java.lang.Object,%20java.lang.Object)]

to convert POJOs → ActionForms and ActionForms → POJOs. To do this, create a new class in src/web/**/service and name it PersonManagerImpl.java. It should extend BaseManager and implement PersonManager.

}]

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;:''The [BaseManager|http://raibledesigns.com/downloads/appfuse/api/org/appfuse/webapp/service/BaseManager.java.html] is for registering different Converters (i.e. [DateConverter|http://raibledesigns.com/downloads/appfuse/api/org/appfuse/common/util/DateConverter.java.html]) so that BeanUtils.copyProperties knows how to convert Strings → Objects. It currently does not have any convenience methods, but does provide a nice place to add them for all your managers.''

{{{

package org.appfuse.webapp.service;

Now let's create a PersonManagerImpl class that implements the methods in PersonManager. To do this, create a new class in src/service/**/service/impl and name it PersonManagerImpl.java. It should extend BaseManager and implement PersonManager.

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import org.apache.commons.beanutils.BeanUtils;

import org.apache.commons.lang.ObjectUtils;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

[{Java2HtmlPlugin

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import org.appfuse.persistence.DAOFactory;

import org.appfuse.persistence.Person;

import org.appfuse.persistence.PersonDao;

import org.appfuse.webapp.form.PersonForm;

package org.appfuse.service.impl;

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public class PersonManagerImpl extends BaseManager implements PersonManager {

//~ Instance fields ========================================================

import org.appfuse.model.Person;

import org.appfuse.dao.PersonDao;

import org.appfuse.service.PersonManager;

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private Log log = LogFactory.getLog(PersonManagerImpl.class);

public class PersonManagerImpl extends BaseManager implements PersonManager {

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private Person person;

private PersonForm personForm;

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//~ Constructors ===========================================================

public void setPersonDao(PersonDao dao) {

this.dao = dao;

}

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public PersonManagerImpl(Object conn)

throws Exception {

dao = (PersonDao) DAOFactory.getInstance(conn, PersonDao.class);

public Person getPerson(String id) {

return dao.getPerson(Long.valueOf(id));

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//~ Methods ================================================================

public void savePerson(Person person) {

dao.savePerson(person);

}

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public Object getPerson(String id) throws Exception {

person = dao.getPerson(Long.valueOf(id));

personForm = new PersonForm();

BeanUtils.copyProperties(personForm, person);

return personForm;

public void removePerson(String id) {

dao.removePerson(Long.valueOf(id));

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}

}]

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public Object savePerson(Object obj) throws Exception {

if (person == null) {

person = new Person();

}

personForm = (PersonForm) obj;

// copy form properties to person

try {

BeanUtils.copyProperties(person, personForm);

} catch (IllegalArgumentException i) {

log.error("Exception occured copying properties", i);

throw new ConversionException();

}

One thing to note is the {{setPersonDao()}} method. This is used by Spring to bind the PersonDao to this Manager. This is configured in the applicationContext-service.xml file. We'll get to configuring that in Step 3[3]. You should be able to compile everything now using "ant compile-service".

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// BeanUtils.copyProperties converts empty Strings to

// Longs with a value of 0 to prevent a NPE.

// Setting the defaultLong to null (in BaseManager) is another solution

if (ObjectUtils.equals(person.getId(), new Long(0))) {

person.setId(null);

}

Now you need to edit Spring's config file for our services layer so it will know about this new Manager.

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dao.savePerson(person);

!!Configure Spring for this Manager and Transactions [#3]

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return getPerson(person.getId().toString());

}

To notify Spring of this our PersonManager interface and its implementation, open the src/service/**/service/applicationContext-service.xml file. Add the following to the bottom of this file.

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public void removePerson(Object obj) throws Exception {

if (person == null) {

person = new Person();

}

personForm = (PersonForm) obj;

if (log.isDebugEnabled()) {

log.debug("removing person: " +

personForm.getFirstName() + " " +

personForm.getLastName());

}

[{Java2HtmlPlugin

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dao.removePerson(person);

}

}}}

You should be able to compile everything now using "ant compile-web". Doh! I guess not:

{{{

PersonManagerImpl.java:11: cannot resolve symbol

[javac] symbol : class PersonForm

[javac] location: package form

[javac] import org.appfuse.webapp.form.PersonForm;

}}}

We need to add XDoclet tags to the Person.java Object to create our Struts ActionForm. In the JavaDoc for the Person.java file, add the following @struts.form tags (use User.java if you need an example):

{{{

* @struts.form include-all="true" extends="BaseForm"

}}}

;:''We extend org.appfuse.webapp.form.BaseForm because it has a toString() method that allows us to call log.debug(formName) to print out a reader-friendly view of the Form object.''

</bean>

}]

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Now, running "ant compile-web" should work just fine.

This bean must have a name that ends in "Manager". This is because there is AOP advice applied at the top of this file for all *Manager beans.

{{{<aop:advisor id="managerTx" advice-ref="txAdvice" pointcut="execution(* *..service.*Manager.*(..))" order="2"/>}}} For more information on transactions with Spring, see [Spring's documentation|http://www.springframework.org/docs/reference/transaction.html].

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Finally, we need to create the PersonManagerTest.properties file in test/web/**/service so that {{personForm = (PersonForm) populate(personForm);}} will work in our test.

!!Run the ManagerTest [#4]

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;:''Duplicating (and renaming) the PersonDaoTest.properties is the easy route. Alternatively, you could set the properties manually. Make sure and add an __id__ property.''

{{{

id=1

firstName=Matt

lastName=Raible

}}}

!!Run the ManagerTest [#3]

Save all your edited files and try running __ant test-service -Dtestcase=PersonManager__.

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Save all your edited files and try running "ant test-web -Dtestcase=PersonManager" one more time.

__Yeah Baby, Yeah:__

''Yeah Baby, Yeah:''

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Total time: 13 seconds%%

Total time: 9 seconds%%

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;:''You'll notice a nice long StackTrace for an ObjectNotFound error - caused by the last part of the "testAddAndRemovePerson" method in PersonManagerTest. You can remove it by removing the e.printStackTrace() in BaseDaoHibernate.retrieveObject(Session ses, Class clazz, Long id).''

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''Next Up:'' __Part II:__ [Creating new Managers|CreateManager] - A HowTo for creating [Business Delegates|http://java.sun.com/blueprints/corej2eepatterns/Patterns/BusinessDelegate.html] that talk to the database tier (DAOs) and the web tier (Struts Actions).

The files that were modified and added to this point are [available for download|https://appfuse.dev.java.net/files/documents/1397/7484/appfuse-tutorial-managers-1.6.zip].

''Next Up:'' __Part III:__ [Creating Actions and JSPs|CreateActions] - A HowTo for creating Actions and JSPs in the AppFuse architecture.

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