1. Spring in Action Craig Walls craig@habuma.com
Blog:
Wiki:

2. About you… Java? .NET? Ruby/Rails? Who’s using Spring? How long?
Java 6? Java 5? Java 1.4? Java 1.3? 1.2 or older?
Who’s using Spring? How long?
Spring 1.2? Spring 2? Spring 2.1?
Favorite session so far?
What brings you to this session?

3. About me Agile developer with Semantra
Natural language business intelligence
Developing software professionally for over 13 years
Telecom, Finance, Retail, Education
Java for most of that
Also some C/C++, C#/.NET, Ruby
Spring fanatic

4. Who this presentation is for
Spring newbies
Crash course in all things Spring
Spring experts
Lots of familiar material
Maybe something you don’t know
Some insight into what’s new and coming up in the next versions of Spring

5. What is Spring?

6. Spring is… A POJO container? A lightweight framework? A platform?
A catalyst for change?

7. Spring does… JSF Spring Batch Tapestry OSGi Ruby Web Flow JMX JMS EJB
Caching
AJAX
Transactions
Portlet
MVC
AOP
Security
Web MVC
Burlap
RMI
Dependency
Injection
Hessian
XML
Groovy
HttpInvoker
JDBC
SOAP
JDO
Spring-WS
JPA
Hibernate
Rich Client
JNDI
iBATIS
JavaConfig
Struts 2/
WebWork 2
Scheduling
JCA
.NET
Struts
Spring
IDE

8. Spring does…
AOP
Dependency
Injection

9. Dependency Injection

10. DI in a nutshell Without DI, objects get their own dependencies
Directly through construction
Through factories
With DI, objects are given their dependencies
Through constructors
Through setter methods
Indirectly through method replacement
DI + interfaces = loosely coupled objects

11. Knights and Quests Imagine a ValiantKnight that embarks on quests
A ValiantKnight needs a Quest
Quest is an interface:
public interface Quest {
void embark(); }

12. What’s wrong with this? public class ValiantKnight {
public void embarkOnQuest() {
Quest quest = new SlayDragonQuest();
quest.embark(); }

13. How about this? public class ValiantKnight{
public void embarkOnQuest() {
Quest quest = QuestFactory.
getInstance().getQuest();
quest.embark(); }

14. Is this any better? public class ValiantKnight {
public void embarkOnQuest() {
InitialContext ctx = null;
try {
ctx = new InitialContext();
Quest quest = (Quest) ctx.lookup(
"java:comp/env/Quest");
quest.embark();
} catch (NamingException e) {
} finally {
if(ctx != null) {
try {ctx.close(); }
catch (Exception e) {} }

15. Let’s try this… public class ValiantKnight { private Quest quest;
public ValiantKnight(Quest quest) {
this.quest = quest; }
public void embarkOnQuest() {
quest.embark();

16. Or perhaps… public class ValiantKnight { private Quest quest;
public ValiantKnight() {}
public void setQuest(Quest quest) {
this.quest = quest; }
public void embarkOnQuest() {
quest.embark();
Where does Quest
come from?
How is it
Implemented?

17. Wiring in Spring (constructor)
<bean id="knight"
class="com.springinaction.ValiantKnight">
<constructor-arg ref="quest" />
</bean>
<bean id="quest"
class="com.springinaction.SlayDragonQuest" />

18. Wiring in Spring (setter)
<bean id="knight"
class="com.springinaction.ValiantKnight">
<property name="quest" ref="quest" />
</bean>
<bean id="quest"
class="com.springinaction.SlayDragonQuest" />

19. Wiring in Spring 2.5 (annotations)
@Component
public class ValiantKnight {
@Autowired
private Quest quest;
public ValiantKnight() {}
public void embarkOnQuest() {
quest.embark(); }

20. Aspect-Oriented Programming

21. AOP in a nutshell
Aspects decouple “concerns” from the objects that they apply to
Common examples: Logging, caching, security, transactions
Imagine a Minstrel class that chronicles a Knight’s exploits in song…

22. Without AOP Is this really the knight’s job?
public void embarkOnQuest() {
minstrel.sing(
"Fa la la, the knight is so brave!");
quest.embark();
"He did embark on a noble quest!"); }
Is this really the knight’s job?

23. With AOP public void embarkOnQuest() { quest.embark(); }
Where’s the Minstrel?

24. Minstrel.java public class Minstrel { public void singBefore() {
System.out.println(
"Fa la la, the knight is so brave!"); }
public void singAfter() {
"He did embark on a noble quest!");

25. Weaving aspects in Spring
<bean id="minstrel" class="com.springinaction.Minstrel" />
<aop:config>
<aop:aspect ref="minstrel">
<aop:pointcut
id="embarkment"
expression="execution(* *.embarkOnQuest(..))" />
<aop:before
method="singBefore"
pointcut-ref="embarkment" />
<aop:after-returning
method="singAfter"
</aop:aspect>
</aop:config>

26. Using @AspectJ @Aspect public class Minstrel {
@Pointcut("execution(* *.embarkOnQuest(..))")
public void embarkment() {}
@Before("embarkment()")
public void singBefore() {
System.out.println(
"Fa la la, the knight is so brave!"); }
@After("embarkment()")
public void singAfter() {
"He did embark on a noble quest!");

27. In Spring XML…
<aop:aspectj-autoproxy />
Yep…that’s it

28. DI meets AOP
@Configurable enables injection into objects not managed by Spring
Domain objects, for example
Configure in Spring XML:
Spring 2.0: <aop:spring-configured/>
Spring 2.1: <context:spring-configured/>
Needs a load-time-weaver:
Spring 2.0: -javaagent:/path/to/aspect-weaver.jar
Spring 2.1…two options:
-javaagent:/path/to/spring-agent.jar
<context:load-time-weaver />

29. Spring and JDBC

30. Conventional JDBC Déjà vu? What do you intend to do about this???
Connection conn = null;
PreparedStatement stmt = null;
ResultSet rs = null;
try {
conn = dataSource.getConnection();
stmt = conn.prepareStatement(”select id, first_name, last_name from Employee where id=?");
stmt.setInt(1, id);
rs.stmt.executeQuery();
Employee employee = null;
if(rs.next()) {
employee = new Employee();
employee.setId(rs.getInt(1));
employee.setFirstName(rs.getString(2));
employee.setLastName(rs.getString(3)); }
return employee;
} catch (SQLException e) {
} finally {
if(rs ! null) { rs.close(); }
if(stmt != null) { stmt.close(); }
if(conn != null) { conn.close(); }
} catch (SQLException e) {}
Déjà vu?
What do you intend
to do about this???

31. SQLException The case of the ambiguous and useless checked exception…
SQLException means that something went wrong with the database…but what?
The types of problems that SQLException represent are usually not runtime- addressable.
What can you do in a catch block to handle a column not found error?

32. Spring’s DataAccessException
CannotAcquireLockException
CannotSerializeTransactionException
CleanupFailureDataAccessException
ConcurrencyFailureException
DataAccessException
DataAccessResourceFailureException
DataIntegrityViolationException
DataRetrievalFailureException
DeadlockLoserDataAccesException
EmptyResultDataAccessException
IncorrectResultSizeDataAccessException
IncorrectUpdateSemanticsDataAccessException
InvalidDataAccessApiUsageException
InvalidDataAccessResourceUsageException
OptimisticLockingFailureException
PermissionDeniedDataAccessException
PessimisticLockingFailureException
TypeMismatchDataAccessException
UncategorizedDataAccessException

33. JDBC: Spring-style Notice no awkward try/catch block And no JDBC
List matches = jdbcTemplate.query(
"select id, first_name, last_name from Employee" +
" where id=?",
new Object[] {Long.valueOf(id)},
new RowMapper() {
public Object mapRow(ResultSet rs, int rowNum)
throws SQLException, DataAccessException {
Employee employee = new Employee();
employee.setId(rs.getInt(1));
employee.setFirstName(rs.getString(2));
employee.setLastName(rs.getString(3));
return employee; }
});
return matches.size() > 0 ?
(Employee) matches.get(0) : null;
Notice no awkward
try/catch block
And no JDBC
boilerplate

34. JDBC Template <bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource" >
<property name="driverClassName”
value="org.hsqldb.jdbcDriver" />
<property name="url"
value="jdbc:hsqldb:hsql://localhost/employee/employee" />
<property name="username" value="sa" />
<property name="password" value="" />
</bean>
<bean id="jdbcTemplate"
class="org.springframework.jdbc.core.JdbcTemplate" >
<property name="dataSource" ref="dataSource" />
<bean id="employeeDao" class="com.springinaction.JdbcEmployeeDao">
<property name="jdbcTemplate" ref="jdbcTemplate" />

35. JDBC: Spring 2 and Java 5 Uses generics No need to wrap No need to
List<Employee> matches = simpleJdbcTemplate.query(
"select id, first_name, last_name from Employee" +
" where id=?",
new ParameterizedRowMapper<Employee>() {
public Employee mapRow(ResultSet rs, int rowNum)
throws SQLException {
Employee employee = new Employee();
employee.setId(rs.getInt(1));
employee.setFirstName(rs.getString(2));
employee.setLastName(rs.getString(3));
return employee; } },
id);
return matches.size() > 0 ? matches.get(0) : null;
Uses generics
No need to wrap
parameters
No need to
cast result

36. One more thing on templates
JDBC isn’t the only place where Spring provides templates…
Hibernate
JPA
JDO
TopLink
iBATIS
JCA
JMS
JNDI

37. Declarative Transactions

38. EJB’s killer feature… …now available in convenient POJO form.
Spring uses AOP to enable declarative transactions on POJO methods
In some ways, even more capable than EJB transactions (more propagation options, isolation levels…)

39. Spring 2 declarative tx <tx:advice id="txAdvice">
<tx:attributes>
<tx:method name="add*" propagation="REQUIRED" />
<tx:method name="*" propagation="SUPPORTS"
read-only="true"/>
</tx:attributes>
</tx:advice>
<aop:config>
<aop:advisor
advice-ref="txAdvice"
pointcut="execution(* *..EmployeeService.*(..))" />
</aop:config>

40. Spring 2 + Java 5 transactions
In service class:
@Transactional(propagation=Propagation.SUPPORTS, readOnly=true)
public class EmployeeServiceImpl implements EmployeeService { …
@Transactional(propagation=Propagation.REQUIRED, readOnly=false)
public void addEmployee(Employee rant) { }
In Spring XML:
<tx:annotation-driven />

41. Spring MVC

42. Why Spring MVC? Spring usually doesn’t reinvent the wheel…
No persistence framework
At one time, Struts was only option
And not necessarily a good option
Spring MVC reinvented the MVC wheel…addressing the shortcomings of Struts

43. Struts 1.x Action public class DisplayCustomerAction extends Action {
public ActionForward execute(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception {
CustomerDetailForm cdf =
(CustomerDetailForm) form;
Customer customer =
lookupCustomer(cdf.getAccountNumber());
request.setAttribute("customer", customer);
return mapping.findForward("customerDetail"); }

44. Spring MVC Controller public class DisplayCustomerController
extends AbstractController {
protected ModelAndView handleRequestInternal(
HttpServletRequest req,
HttpServletResponse response) throws Exception {
long customerId =
Long.valueOf(req.getParameter("id"));
Customer customer = lookupCustomer(customerId);
return new ModelAndView(
"customerDetail", customer); }

45. Mapping URLs to controllers
SimpleUrlHandlerMapping:
<bean id="urlMapping"
class="org.springframework.web.servlet.handler.
SimpleUrlHandlerMapping">
<property name="mappings">
<value>
/home.htm=homeController
/login.htm=loginController
/addSpittle.htm=addSpittleController
/addSpitter.htm=addSpitterController
</value>
</property>
</bean>

46. Auto-mapping of controllers
ControllerClassNameHandlerMapping:
<bean id="urlMapping"
class="org.springframework.web.servlet.mvc.support.
ControllerClassNameHandlerMapping" />
/home.htm HomeController
/login.htm LoginController
/addspittle.htm AddSpittleController

47. Mapping view names to views
InternalResourceViewResolver:
<bean id="jspViewResolver"
class="org.springframework.web.servlet.view.
InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/" />
<property name="suffix" value=".jsp" />
</bean>
“home” /WEB-INF/jsp/home.jsp
“login” /WEB-INF/jsp/login.jsp
“orderForm” /WEB-INF/jsp/orderForm.jsp

48. The Struts 1.x Action selection

49. Spring Controller Selection

50. Spring 2.5 Controllers Annotated with @Controller
So that <context:component-scan> can find and register them
Also annotated
To map requests to handler methods
Optionally annotated
Transparently stores model attributes in session
Parameters can be mapped
To automatically map request parameters to handler method parameters.
Parameters can also be mapped
Maps a model attribute to a method parameter
@ModelAttribute can also be applied to methods
To populate the model with the output from the method

51. Minimal XML needed for MVC
<context:component-scan
base-package="com.habuma.spitter.mvc" />
<bean
class="org.springframework.web.servlet.
mvc.annotation.
AnnotationMethodHandlerAdapter" />
Auto-register all classes in
com.habuma.spitter.mvc package
Map beans

52. Annotated controller example
@RequestMapping("/editPet.do")
@SessionAttributes("pet")
public class EditPetForm {
@ModelAttribute("types")
public Collection<PetType> populatePetTypes() { return this.clinic.getPetTypes(); }
@RequestMapping(type = "POST")
public String Pet pet, BindingResult result, SessionStatus status) {
new PetValidator().validate(pet, result);
if (result.hasErrors()) { return "petForm"; }
else {
this.clinic.storePet(pet);
status.setComplete();
return "redirect:owner.do?ownerId=" + pet.getOwner().getId(); }

53. Annotated controller (2)
@RequestMapping("/editPet.do")
@SessionAttributes("pet")
public class EditPetForm { …
@RequestMapping(type = "GET")
public String setupForm(
@RequestParam("petId") int petId, ModelMap model) {
Pet pet = this.clinic.loadPet(petId);
model.addAttribute("pet", pet);
return "petForm"; }

54. What about…??? Struts 2/WebWork 2? JSF? Tapestry? Wicket? Seam?
Grails?
The billions of other MVC frameworks

55. What’s new in Spring 2 New/extensible configuration namespaces
Easier AOP and support
Easier transactions
Injection into objects not managed by Spring
Support for JPA
Asynchronous JMS support
New JDBC templates (Java 5 and named parameters)
New form-binding JSP tag library
Portlet MVC
Dynamic language beans (JRuby, Groovy, BeanShell)
JMX: Notifications and registration control
Convention over configuration improvements

56. What’s coming in Spring 2.5
JMS configuration namespace
Context configuration namespace
<aop:spring-configured> moves to <context:spring-configured>
Annotation-driven configuration
@RequestParam
Autodetected components
Requires JDK 1.4 or higher
Named parameters added to SimpleJdbcTemplate
ParameterizedBeanPropertyRowMapper for automatically mapping between columns and bean properties
<context:load-time-weaver/> : Spring configured load time weaving
Hibernate 2.1 support goes away
JUnit 4.x support (SpringJUnit4ClassRunner)

57. Don’t forget to turn in evals!!!
Q & A
Don’t forget to turn in evals!!!