CreateManager

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About this Tutorial

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 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.

I will tell you how I do stuff in the Real World in text like this.

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

Table of Contents

• [1] Create a new ManagerTest to run JUnit tests on the Manager
• [2] Create a new Manager to talk to the DAO
• [3] Run the ManagerTest

Create a new ManagerTest to run JUnit tests on the Manager [#1]

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.

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 class.

package org.appfuse.webapp.service;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.appfuse.webapp.form.PersonForm;

public class PersonManagerTest extends BaseManagerTestCase {
    //~ Instance fields ========================================================

    private PersonManager mgr = null;
    private Log log = LogFactory.getLog(PersonManagerTest.class);
    private PersonForm personForm;

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

    public PersonManagerTest(String name) {
        super(name);
    }

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

    protected void setUp() throws Exception {
        super.setUp();
        mgr = new PersonManagerImpl(conn);
    }

    protected void tearDown() throws Exception {
        super.tearDown();
        mgr = null;
    }

    public static void main(String[] args) {
        junit.textui.TestRunner.run(PersonManagerTest.class);
    }
}

...we create methods that begin with "test" (all lower case). As long as these methods are public, have a void return type and take no arguments, they will be called by our <junit> task in our Ant build.xml file. Here's some simple tests for testing CRUD. An important thing to remember is that each method (also known as a test), should be autonomous.

Add the following methods to your PersonManagerTest.java file:

    public void testGetPerson() throws Exception {
        personForm = (PersonForm) mgr.getPerson("1");

        if (log.isDebugEnabled()) {
            log.debug(personForm);
        }

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

    public void testSavePerson() throws Exception {
        personForm = (PersonForm) mgr.getPerson("1");
        personForm.setFirstName("Joe");

        if (log.isDebugEnabled()) {
            log.debug("saving person with updated firstName: " + personForm);
        }

        personForm = (PersonForm) mgr.savePerson(personForm);
        assertTrue(personForm.getFirstName().equals("Joe"));
    }

    public void testAddAndRemovePerson() throws Exception {
        personForm = new PersonForm();

        // call populate method in super class to populate test data
        // from a properties file matching this class name
        personForm = (PersonForm) populate(personForm);

        personForm = (PersonForm) mgr.savePerson(personForm);
        assertTrue(personForm.getLastName().equals("Raible"));

        if (log.isDebugEnabled()) {
            log.debug("removing person...");
        }

        mgr.removePerson(personForm);

        try {
            personForm = (PersonForm) mgr.getPerson("1");
            fail("Expected 'Exception' not thrown");
        } catch (Exception e) {
            if (log.isDebugEnabled()) {
                log.debug(e);
            }

            assertTrue(e != null);
        }
    }

Manager mgr = new ManagerImp(conn);

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

I think it's funny how I've followed so many patterns to allow extendibility in AppFuse. In reality, on most projects I've been on - I learn so much in a year that I don't want to extend the architecture - I want to rewrite it. Hopefully by keeping AppFuse up to date with my perceived best practices, this won't happen as much. Each year will just be an upgrade to the latest AppFuse, rather than a re-write. ;-)

Create a new Manager to talk to the DAO [#2]

As usual, I usually duplicate (open → save as) an existing file (i.e. UserManager.java).

package org.appfuse.webapp.service;

public interface PersonManager {

    public Object getPerson(String id) throws Exception;

    public Object savePerson(Object person) throws Exception;

    public void removePerson(Object Person) throws Exception;
}

The BaseManager is for registering different Converters (i.e. DateConverter) 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;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.lang.ObjectUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.appfuse.persistence.DAOFactory;
import org.appfuse.persistence.Person;
import org.appfuse.persistence.PersonDao;
import org.appfuse.webapp.form.PersonForm;

public class PersonManagerImpl extends BaseManager implements PersonManager {
    //~ Instance fields ========================================================

    private Log log = LogFactory.getLog(PersonManagerImpl.class);
    private PersonDao dao;
    private Person person;
    private PersonForm personForm;

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

    public PersonManagerImpl(Object conn)
    throws Exception {
        dao = (PersonDao) DAOFactory.getInstance(conn, PersonDao.class);
    }

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

    public Object getPerson(String id) throws Exception {
        person = dao.getPerson(Long.valueOf(id));
        
        personForm = new PersonForm();
        BeanUtils.copyProperties(personForm, person);
        
        return personForm;
    }

    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();
        }

        // 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);
        }

        dao.savePerson(person);

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

    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());
        }

        dao.removePerson(person);
    }

PersonManagerImpl.java:11: cannot resolve symbol
    [javac] symbol  : class PersonForm 
    [javac] location: package form
    [javac] import org.appfuse.webapp.form.PersonForm;

* @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.

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

Run the ManagerTest [#3]