The document provides an overview of the Spring Framework, detailing its lightweight container, dependency injection, and the modularity it offers for building applications. It discusses various concepts such as inversion of control, different types of bean creation and lifecycle management, and the support for aspect-oriented programming (AOP) to manage cross-cutting concerns. The document also highlights the framework's capabilities for data access and transaction management, making it a powerful tool for Java development.

1. Spring

2. Spring Overview
 “Lightweight Container”
 Very loosely coupled
 Components widely reusable and separately
packaged
 Created by Rod Johnson
 Based on “Expert one-on-one J2EE Design and
Development”
 Currently on version 1.1.1

3. Why Use Spring?
 Wiring of components (Dependency Injection)
 Promotes/simplifies decoupling, design to interfaces, TDD
 Declarative programming without J2EE
 Easily configured aspects, esp. transaction support
 Simplify use of popular technologies
 Abstractions insulate application from specifics, eliminate
redundant code, and handle common error conditions
 Underlying technology specifics still accessible (closures)

4. Why Use Spring?
 Conversion of checked exceptions to
unchecked
 (Or is this a reason not to use it?)
 Not an all-or-nothing solution
 Extremely modular and flexible
 Well designed
 Easy to extend
 Many reusable classes

5. Spring Framework

6. Spring Application

7. Spring Dependency Injection
 Inversion of Control (IoC)
 “Hollywood Principle”
 Don't call me, I'll call you
 “Container” resolves (injects) dependencies of
components by setting implementation object (push)
 As opposed to component instantiating or Service
Locator pattern where component locates
implementation (pull)
 Martin Fowler calls Dependency Injection

8. Dependency Injection Variants
 Variations on dependency injection
 Interface based (Avalon)
 Constructor-based (PicoContainer, Spring)
 Setter-based (Spring)
 BeanFactory provides configuration framework to
initialize and “wire” JavaBeans
 org.springframework.beans and
org.springframework.context
 Typically use the XmlBeanFactory, employing XML
configuration files

9. Dependency Injection (cont'd)
 BeanFactory configured components need have
no Spring dependencies
 Simple JavaBeans
 Beans are singletons by default
 Properties may be simple values or references to
other beans
 Built-in support for defining Lists, Maps, Sets,
and Properties collection types.
 Custom PropertyEditors may be defined to
convert string values to other, arbitrary types.

10. XmlBeanFactory Example
 Property and constructor based IoC
<bean id="exampleBean" class="examples.ExampleBean">
<property name="beanOne"><ref bean="anotherExampleBean"/></property>
<property name="beanTwo"><ref bean="yetAnotherBean"/></property>
<property name="integerProperty">1</property>
</bean>
<bean id="anotherExampleBean" class="examples.AnotherBean"/>
<bean id="yetAnotherBean" class="examples.YetAnotherBean"/>
<bean id="exampleBean" class="examples.ExampleBean">
<constructor-arg><ref bean="anotherExampleBean"/></constructor-arg>
<constructor-arg><ref bean="yetAnotherBean"/></constructor-arg>
<constructor-arg><value>1</value></constructor-arg>
</bean>
<bean id="anotherExampleBean" class="examples.AnotherBean"/>
<bean id="yetAnotherBean" class="examples.YetAnotherBean"/>

11. Bean Creation
 Direct instantiation
 <bean id=“beanId” class=“className”>
 BeanFactory instantiation
 Same syntax but class is subclass of BeanFactory
 getObject() called to obtain Bean
 Static Factory
 <bean id=“beanId” class=“className" factory-method="
staticCreationMethod“>
 Instance Factory Method
 <bean id=“beanId” factory-bean=“existingBeanId" factory-
method=“nonStaticCreationMethod">

12. Bean Creation
 Beans may be singletons or “prototypes”
 Attribute singleton=“false” causes instantiation
with each getBean() lookup
 Singleton is default
 XmlBeanFactory pre-instantiates singletons
 May be overridden on per-instance basis by lazy-
init=“true”
 Beans may also be marked abstract, allowing
reuse of attribute values through inheritance

13. Autowiring Properties
 Beans may be auto-wired (rather than using <ref>)
 Per-bean attribute autowire
 Explicit settings override
 autowire=“name”
 Bean identifier matches property name
 autowire=“type”
 Type matches other defined bean
 autowire=”constructor”
 Match constructor argument types
 autowire=”autodetect”
 Attempt by constructor, otherwise “type”

14. Dependency Checking
 Ensures properties are defined
 Per-bean attribute dependency-check
 None required by default
 Verifies autowiring succeeded
 “simple”
 all but collaborators
 “object”
 collaborators only
 “all”
 Collaborators, primitive types, and collections

15. Lifecycle Customization
 Can define init method called after properties set
 init-method=”<method-name>”
 Can define destroy method as shutdown hook
 destroy-method=”<method-name>”
 May alternatively implement InitializingBean
and/or DisposableBean
 At cost of Spring dependency

16. BeanFactory Miscellany
 BeanFactoryAware interface provides BeanFactory for
bean
 setBeanFactory(BeanFactory)
 BeanNameAware interface provides bean name
 setBeanName(String)
 FactoryBean for beans which are themselves factories
 Object getObject()
 Boolean isSingleton()
 Class getObjectType()

17. BeanFactory Usage
InputStream is = new FileInputStream("beans.xml");
XmlBeanFactory factory = new XmlBeanFactory(is);
MyBeanClass bean = (MyBeanClass)factory.getBean(“myBean”);
ApplicationContext ctx = new
ClassPathXmlApplicationContext("beans.xml");
MyBeanClass bean = (MyBeanClass)ctx.getBean(“myBean”);
OR

18. ApplicationContext
 Extends functionality of BeanFactory
 Pre-instantiates singleton beans
 Detects and registers BeanPostProcessors and
BeanFactoryPostProcessors
 Supports nesting of contexts
 ApplicationListener and ApplicationEvents
 Initialized and closed predefined
 Custom may be created
 MessageSource provides i18n messaging
 <bean id=”messageSource”
class=”...ResourceBundleMessageSource”/>
 Contains list of bundle base names

19. Web Initialization
 Web applications may use
ContextLoaderListener to initialize Spring
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/daoContext.xml /WEB-INF/applicationContext.xml
</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
web.xml
Automatically done by Spring DispatcherServlet

20. Specialized Beans
 MethodInvokingFactoryBean
 Invokes method on registered beans or any static
methods
 Stores return value
 SingletonBeanFactoryLocator and
ContextSingletonBeanFactoryLocator
 Useful for sharing BeanFactories
 Eliminate duplication of beans in multiple similar
factories or contexts

21. ApplicationContext customization
 Defined beans inheriting from
BeanFactoryPostProcessor are detected and invoked
 CustomEditorConfigurer
 Registers custom PropertyEditors for converting
configuration string values to specific types
 AutoProxyCreators
 Wrap beans in proxies based on various criteria (name,
metadata, etc)
 PropertyResourceConfigurer
 Sets from property file and/or system properties

22. ApplicationContext Example
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location"><value>database.properties</value></property>
</bean>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName">
<value>${database.connection.driver_class}</value>
</property>
<property name="url">
<value>${database.connection.url}</value>
</property>
</bean>

23. Spring AOP

24. AOP Fundamentals
 Aspect-oriented programming (AOP) provides for
simplified application of cross-cutting concerns
 Transaction management
 Security
 Logging
 Auditing
 Locking
 AOP sometimes (partially) achieved via Decorators or
Proxies
 CORBA Portable Interceptors
 Servlet Filters

25. AOP Fundamentals
 Aspect - Implementation of a cross-cutting concern.
 Spring Advisors or Interceptors
 Joinpoint - Execution point to target
 Typically, methods
 Advice - Action taken at a particular joinpoint.
 Pointcut - A set of joinpoints specifying where advice
should be applied (e.g. Regular expression)
 Introduction/Mixin - Adding methods or fields to an
advised class.
 Weaving - Assembling aspects into advised objects.

26. Spring AOP
 Generally, applies aspects to beans using BeanFactory
 Uses Dynamic Proxies if interface available
otherwise CGLIB
 CGLIB creates derived class which proxies requests
 Bean class may not be final
 Less capable than AspectJ
 does not have field interception
 only runtime weaving solution is available
 Closer integration with AspectJ anticipated

27. Spring Pointcuts
 Pointcut applicability to a class may be evaluated
statically or dynamically
 Spring only creates proxies where necessary
public interface Pointcut {
ClassFilter getClassFilter();
MethodMatcher getMethodMatcher();
}
public interface ClassFilter {
boolean matches(Class clazz);
}

28. Pointcuts (cont'd)
public interface MethodMatcher {
boolean matches(Method m, Class targetClass);
boolean isRuntime();
boolean matches(Method m, Class targetClass, Object[] args);
}
 Pointcut may be statically or dynamically
evaluated based on isRuntime()
 Abstract class StaticMethodMatcherPointcut
requires override of 1st
method only
Only called if isRuntime() == true

29. Pointcuts (cont'd)
 Spring predefined pointcuts
 In org.springframework.aop.support package
 RegexpMethodPointcut
 Union of multiple regular expressions
 Uses Jakarta ORO package
 ControlFlowPointcut
 Similar to AspectJ cflow
 Applied if call stack includes specific class and, optionally,
method
 UnionPointcut
 Merges pointcuts

30. Spring Advice
 Can have per-class or per-instance Advice
 Spring provides several Advice types
 Around Advice
 AOP Alliance compliant
 Must call invocation.proceed() to call target
public class MyAdvice implements AroundAdvice {
Object invoke(MethodInvocation invocation) {
// change arguments, start transaction, lock, etc.
invocation.proceed();
// change return value, stop transaction, unlock,etc.
}
}

31. Spring Advice
 MethodBeforeAdvice
 void before(Method m, Object[] args, Object target)
 Cannot alter return type
 ThrowsAdvice
 Marker interface
 Implementors define methods of form:
 afterThrowing([Method], [args], [target], subclassOfThrowable)
 AfterReturningAdvice
 void afterReturning(Object returnValue, Method, m,
Object[] args, Object target)
 Cannot modify return value

32. Spring Advice
 IntroductionInterceptor provides ability to define
mixins
public class RollbackAdvice extends DelegatingIntroductionInterceptor
implements RollbackSupport {
Map map = new HashMap();
void rollback(Date date) {
// rollback to state at given time
}
public Object invoke(MethodInvocation invocation) {
// record change and time of change
}
}

33. Injecting Advice
<bean id=“meetingTarget" class=“ex.DefaultMeeting“
singleton=“false”>
<property name=“topic">Spring</property>
</bean>
<bean id="myAdvisor" class=“ex.RollbackAdvice"
singleton=”false”>
</bean>
<bean id="debugInterceptor"
class="org.springframework.aop.interceptor.DebugInterceptor">
</bean>

34. Injecting Advice (cont'd)
<bean id=“meeting"
class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="proxyInterfaces">
<value>ex.Meeting</value>
</property>
<property name="target"><ref local=“meetingTarget"/></property>
<property name="interceptorNames">
<list>
<value>myAdvisor</value>
<value>debugInterceptor</value>
</list>
</property>
</bean>
Advisors applied in order
All methods
using CGLib
if none defined

35. Autoproxying
 Autoproxy bean definitions automatically proxy
selected beans.
 BeanNameAutoProxyCreator
 Adds listed advisors/interceptors to beans
with names matching regular expression
 DefaultAdvisorAutoProxyCreator
 Generic autoproxy infrastructure support
 Applies all advisors defined in the context to
all beans, proxying appropriately

36. Metadata support
 Spring supports obtaining meta data Object
attributes at class, method, and field level
 Not yet argument level (as JSR-175)
 Currently supports Jakarta Commons Attributes
 Support for JSR-175 in work
 Metadata support provided via Attributes
interface
 Amenable to mocking unlike JDK reflection and
Commons static methods

37. Metadata autoproxying
 Configuration of autoproxying based on metadata
attributes simplifies configuration
 Define custom attribute class
 Define Advisor with pointcut based on custom attribute
 Add Advisor in ApplicationContext with autoproxy
 Examples
 Transaction Attributes
 Security Attributes
 Pooling
 Mapping of controllers to URLs

38. Transactions

39. AOP Transactions
 Spring provides AOP support for declarative
transactions
 Delegates to a PlatformTransactionManager
instance
 DataSourceTransactionManager
 HibernateTransactionManager
 JdoTransactionManager
 JtaTransactionManager

40. Transaction Configuration
<bean id="sessionFactory"
class="org.springframework.orm.hibernate.LocalSessionFactoryBean">
<property name="dataSource"><ref bean="dataSource"/></property>
<property name="mappingResources">
<list>
<value>com/../model/*.hbm.xml</value>
</list>
</property>
</bean>
<bean id="transactionManager”
class="org.springframework.orm.hibernate.HibernateTransactionManager">
<property name="sessionFactory">
<ref bean="sessionFactory"/>
</property>
</bean>

41. Declarative Transactions
 Declarative transactional support can be added to
any bean by using TransactionProxyFactoryBean
 Similar to EJB, transaction attributes may be
defined on a per-method basis
 Also allows definition of pre- and post-
interceptors (e.g. for security)

42. Injecting Transaction Support
<bean id=“reservationService"
class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
<property name="transactionManager">
<ref bean="transactionManager"/>
</property>
<property name="target"><ref local=“reservationServiceTarget"/></property>
<property name="transactionAttributes">
<props>
<prop key=“reserveRoom*">PROPAGATION_REQUIRED</prop>
<prop key="*">PROPAGATION_REQUIRED,readOnly</prop>
</props>
</property>
</bean>
Declarative transaction support for single bean

43. Transaction Autoproxy
<bean id="autoproxy"
class="org...DefaultAdvisorAutoProxyCreator">
</bean>
<bean id="transactionAdvisor"
class="org...TransactionAttributeSourceAdvisor"
autowire="constructor" >
</bean>
<bean id="transactionInterceptor"
class="org...TransactionInterceptor"
autowire="byType">
</bean>
<bean id="transactionAttributeSource"
class="org...AttributesTransactionAttributeSource"
autowire="constructor">
</bean>
<bean id="attributes"
class="org...CommonsAttributes"
/>
Caches metadata
from classes
Generic autoproxy
support
Applies transaction
using transactionManager
Invokes interceptor
based on attributes

44. Data Access

45. Data Access
 DAO support provides pluggable framework for
persistence
 Currently supports JDBC, Hibernate, JDO, and
iBatis
 Defines consistent exception hierarchy (based on
RuntimeException)
 Provides abstract “Support” classes for each
technology
 Template methods define specific queries

46. Hibernate DAO Example
public class ReservationDaoImpl extends HibernateDaoSupport
implements ReservationDao {
public Reservation getReservation (Long orderId) {
return (Reservation)getHibernateTemplate().load(Reservation .class,
orderId);
}
public void saveReservation (Reservation r) {
getHibernateTemplate().saveOrUpdate(r);
}
public void remove(Reservation Reservation) {
getHibernateTemplate().delete(r);
}

47. Hibernate DAO (cont’d)
public Reservation[] findReservations(Room room) {
List list = getHibernateTemplate().find(
"from Reservation reservation “ +
“ where reservation.resource =? “ +
“ order by reservation.start",
instrument);
return (Reservation[]) list.toArray(new Reservation[list.size()]);

48. Hibernate DAO (cont’d)
public Reservation[] findReservations(final DateRange range) {
final HibernateTemplate template = getHibernateTemplate();
List list = (List) template.execute(new HibernateCallback() {
public Object doInHibernate(Session session) {
Query query = session.createQuery(
"from Reservation r “ +
“ where r.start > :rangeStart and r.start < :rangeEnd “);
query.setDate("rangeStart", range.getStartDate()
query.setDate("rangeEnd", range.getEndDate())
return query.list();
}
});
return (Reservation[]) list.toArray(new Reservation[list.size()]);
}
}

49. Hibernate Example
<bean id="sessionFactory"
class="org.springframework.orm.hibernate.LocalSessionFactoryBean">
<property name="dataSource"><ref bean="dataSource"/></property>
<property name="mappingResources">
<list>
<value>com/jensenp/Reservation/Room.hbm.xml</value>
<value>com/jensenp/Reservation/Reservation.hbm.xml</value>
<value>com/jensenp/Reservation/Resource.hbm.xml</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">${hibernate.dialect}</prop>
<prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}
</prop>
<prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
</props>
</property>
</bean>
<bean id=“reservationDao"
class="com.jensenp.Reservation.ReservationDaoImpl">
<property name="sessionFactory"><ref bean="sessionFactory"/>
</property>
</bean>

50. JDBC Support
 JDBCTemplate provides
 Translation of SQLExceptions to more meaningful
Spring Runtime exceptions
 Integrates thread-specific transactions
 MappingSQLQuery simplifies mapping of
ResultSets to Java objects

51. Web Framework

52. DispatcherServlet
 The DispatcherServlet is the Spring Front
Controller
 Initializes WebApplicationContext
 Uses /WEB-INF/[servlet-name]-servlet.xml by
default
 WebApplicationContext is bound into
ServletContext

53. DispatcherServlet Configuration
 HandlerMapping
 Routing of requests to handlers
 HandlerAdapter
 Adapts to handler interface. Default utilizes Controllers
 HandlerExceptionResolver
 Maps exceptions to error pages
 Similar to standard Servlet, but more flexible
 ViewResolver
 Maps symbolic name to view

54. Dispatcher Servlet Configuration
 MultipartResolver
 Handling of file upload
 LocaleResolver
 Default uses HTTP accept header, cookie, or
session

55. Controllers
 Controller interface defines one method
 ModelAndView handleRequest(HttpServletRequest
req, HttpServletResponse resp) throws Exception
 ModelAndView consists of a view identifier and
a Map of model data

56. Controller Implementations
 CommandControllers bind parameters to data
objects
 AbstractCommandController
 AbstractFormController
 SimpleFormController
 WizardFormController