Spring

1
Spring
2

• Spring Overview
• Spring Container Concepts
• Spring and AOP
• Spring and Data Access
• Managing Transactions and Resources
• Remoting and Accessing Enterprise Services
• Spring Web Framework
• Integrating with Struts
• DAO and LDAP support

3
Spring Overview

• Spring is a Lightweight Application Framework
• Spring Promotes loose coupling through Inversion
  of Control (IoC)
• Spring comes with rich support for
• Aspect-Oriented Programming.

4
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

5
Why Use Spring?

• Wiring of components (Dependency Injection)
• Promotes/simplifies decoupling, design to
  interfaces
• Declarative programming without J2EE
• Easily configured aspects, esp. transaction
  support

6
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

7
Architectural benefits

• Spring can effectively organize your middle tier
  objects, whether or not you choose to use EJB.
• Spring's configuration management services can be
  used in any architectural layer, in whatever
  runtime environment.
• Spring can use AOP to deliver declarative
  transaction management without using an EJB
  container.

8
Architectural benefits

• Spring provides a consistent framework for data
  access, whether using JDBC or an O/R mapping
  product such as TopLink, Hibernate
• Spring provides a consistent, simple programming
  model in many areas JDBC, JMS, JavaMail, JNDI and
  many other important APIs.

9
Spring Framework

• The Spring framework is a layered architecture
  consisting of seven well-defined modules. The
  Spring modules are built on top of the core
  container, which defines how beans are created,
  configured and managed.

10
Spring Framework
11
Spring Framework

• Core container
• Provides the essential functionality of the
  Spring
• framework.
• Primary component of the core container is the
  
• BeanFactory, an implementation of the Factory
  
• pattern.
• BeanFactory applies the Inversion of Control
  (IOC)
• pattern to separate an application's
  configuration and
• dependency specification from the actual
  application code.

12
Spring Framework

• Spring context
• Spring context is a configuration file that
  provides context information to the Spring
  framework. The Spring context includes enterprise
  services such as JNDI, EJB, e-mail, validation,
  and scheduling functionality.

13
Spring Framework

• Spring AOP
• The Spring AOP integrates aspect-oriented
  functionality directly into the Spring framework.
• Provides transaction management services for
  objects in any Spring-based application.
• Incorporates declarative transaction
  management capabilities into applications without
  relying on EJB components.

14
Spring Framework

• Spring DAO
• Spring JDBC DAO abstraction layer offers
  exception hierarchy for managing the exception
  handling and error messages thrown by different
  database vendors.
• The exception hierarchy simplifies error handling
  and greatly reduces the amount of exception code
  you need to write, such as opening and closing
  connections.
• Spring DAO's JDBC-oriented exceptions comply to
  its generic DAO exception hierarchy.

15
Spring Framework

• Spring ORM
• The Spring framework plugs into several ORM
  frameworks to provide its Object Relational tool,
  including JDO and Hibernate.
• All of these comply to Spring's generic
  transaction and DAO exception hierarchies.

16
Spring Framework

• Spring Web module
• The Web context module builds on top of the
  application context module, providing contexts
  for Web-based applications.
• The Web module also eases the tasks of
  handling multi-part requests and binding request
  parameters to domain objects.

17

• Spring MVC framework
• The Model-View-Controller (MVC) framework
  featured MVC implementation for building Web
  applications.
• The MVC framework is highly configurable via
  strategy interfaces and accommodates numerous
  view technologies including JSP, Velocity, Tiles
  and iText.

18
Aspect Oriented Programming

• Aspect-oriented programming, or AOP, is a
  programming technique that allows programmers to
  modularize crosscutting concerns, or behavior
  that cuts across the typical divisions of
  responsibility, such as logging and transaction
  management.

19
BeanFactory Usage
InputStream is new FileInputStream("beans.xml")
XmlBeanFactory factory new XmlBeanFactory(is)
MyBeanClass bean (MyBeanClass)factory.getBean(
myBean)
OR
ApplicationContext ctx new ClassPathXmlApplicati
onContext("beans.xml") MyBeanClass bean
(MyBeanClass)ctx.getBean(myBean)
20
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

21
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.

22
XmlBeanFactory Example

• Property and constructor based IoC

ltbean id"exampleBean" class"examples.ExampleBean
"gt ltproperty name"beanOne"gtltref
bean"anotherExampleBean"/gtlt/propertygt
ltproperty name"beanTwo"gtltref bean"yetAnotherBean
"/gtlt/propertygt ltproperty name"integerProperty
"gt1lt/propertygt lt/beangt ltbean id"anotherExampleBe
an" class"examples.AnotherBean"/gt ltbean
id"yetAnotherBean" class"examples.YetAnotherBean
"/gt
ltbean id"exampleBean" class"examples.ExampleBean
"gt ltconstructor-arggtltref bean"anotherExampleB
ean"/gtlt/constructor-arggt ltconstructor-arggtltref
bean"yetAnotherBean"/gtlt/constructor-arggt
ltconstructor-arggtltvaluegt1lt/valuegtlt/constructor-arg
gt lt/beangt ltbean id"anotherExampleBean"
class"examples.AnotherBean"/gt ltbean
id"yetAnotherBean" class"examples.YetAnotherBean
"/gt
23
Bean Creation

• Direct instantiation
• ltbean idbeanId classclassNamegt
• BeanFactory instantiation
• Same syntax but class is subclass of BeanFactory
• getObject() called to obtain Bean
• Static Factory
• ltbean idbeanId classclassName"
  factory-method" staticCreationMethodgt
• Instance Factory Method
• ltbean idbeanId factory-beanexistingBeanId"
  factory-methodnonStaticCreationMethod"gt

24
Autowiring Properties

• Beans may be auto-wired (rather than using ltrefgt)
• Per-bean attribute autowire
• Explicit settings override
• autowirename
• Bean identifier matches property name
• autowiretype
• Type matches other defined bean
• autowireconstructor
• Match constructor argument types
• autowireautodetect
• Attempt by constructor, otherwise type

25
Web Initialization

• Web applications may use ContextLoaderListener to
  initialize Spring

web.xml
ltcontext-paramgt ltparam-namegtcontextConfigLocat
ionlt/param-namegt ltparam-valuegt/WEB-INF/daoConte
xt.xml /WEB-INF/applicationContext.xml
lt/param-valuegt lt/context-paramgt ltlistenergt
ltlistener-classgtorg.springframework.web.context.C
ontextLoaderListenerlt/listener-classgt
lt/listenergt
Automatically done by Spring DispatcherServlet
26
ApplicationContext Example
ltbean id"propertyConfigurer"
class"org.springframework.beans.factory.config.Pr
opertyPlaceholderConfigurer"gt ltproperty
name"location"gtltvaluegtdatabase.propertieslt/valuegt
lt/propertygt lt/beangt ltbean
id"dataSource" class"org.springframework
.jdbc.datasource.DriverManagerDataSource"gt
ltproperty name"driverClassName"gt
ltvaluegtdatabase.connection.driver_classlt/valuegt
lt/propertygt ltproperty
name"url"gt ltvaluegtdatabase.connecti
on.urllt/valuegt lt/propertygt lt/beangt
27
Spring AOP
28
AOP Fundamentals

• Aspect-oriented programming (AOP) provides for
  simplified application of cross-cutting concerns
• Transaction management
• Security
• Logging
• Auditing
• Locking

29
Transactions
30
AOP Transactions

• Spring provides AOP support for declarative
  transactions
• Delegates to a PlatformTransactionManager
  instance
• DataSourceTransactionManager
• HibernateTransactionManager
• JdoTransactionManager
• JtaTransactionManager

31
Transaction Configuration
ltbean id"sessionFactory" class"org.springfra
mework.orm.hibernate.LocalSessionFactoryBean"gt
ltproperty name"dataSource"gtltref
bean"dataSource"/gtlt/propertygt ltproperty
name"mappingResources"gt ltlistgt
ltvaluegtcom/../model/.hbm.xmllt/valuegt
lt/listgt lt/propertygt lt/beangt ltb
ean id"transactionManager class"org.springfram
ework.orm.hibernate.HibernateTransactionManager"gt
ltproperty name"sessionFactory"gt ltref
bean"sessionFactory"/gt lt/propertygt lt/beangt
32
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

33
Injecting Transaction Support
Declarative transaction support for single bean
ltbean idreservationService"
class"org.springframework.transaction.interceptor
.TransactionProxyFactoryBean"gt ltproperty
name"transactionManager"gt ltref
bean"transactionManager"/gt lt/propertygt
ltproperty name"target"gtltref localreservationSer
viceTarget"/gtlt/propertygt ltproperty
name"transactionAttributes"gt ltpropsgt
ltprop keyreserveRoom"gtPROPAGATION_REQUIRED
lt/propgt ltprop key""gtPROPAGATION_REQUIR
ED,readOnlylt/propgt lt/propsgt
lt/propertygt lt/beangt
34
Transaction Autoproxy
ltbean id"autoproxy" class"org...DefaultAdvi
sorAutoProxyCreator"gt lt/beangt ltbean
id"transactionAdvisor" class"org...Transacti
onAttributeSourceAdvisor" autowire"constructo
r" gt lt/beangt ltbean id"transactionInterceptor"
class"org...TransactionInterceptor"
autowire"byType"gt lt/beangt ltbean
id"transactionAttributeSource"
class"org...AttributesTransactionAttributeSource"
autowire"constructor"gt lt/beangt ltbean
id"attributes" class"org...CommonsAttributes
" /gt
Generic autoproxy support
Invokes interceptor based on attributes
Applies transaction using transactionManager
Caches metadata from classes
35
Data Access
36
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

37
DAO Support

• The Data Access Object (DAO) support in Spring
  is primarily aimed at making it easy to work with
  data access technologies like JDBC, Hibernate or
  JDO in a standardized way.

38
DAO Support

• ltbean id"dataSource" class"org.springframework.
  jndi.JndiObjectFactoryBean" lazy-init"default"
  autowire"default" dependency-check"default"gt
• ltproperty name"jndiName"gt
• ltvaluegtcom.bt.bbv.r1osslt/valuegt
• lt/propertygt
• lt/beangt
• ltbean id"jdbcTemplate" class"org.springframewor
  k.jdbc.core.JdbcTemplate" lazy-init"default"
  autowire"default" dependency-check"default"gt
• ltproperty name"dataSource"gt
• ltref bean"dataSource" /gt
• lt/propertygt
• lt/beangt
• lt/beansgt

39
Hibernate DAO Example
public class ReservationDaoImpl extends
HibernateDaoSupport implements
ReservationDao public Reservation
getReservation (Long orderId) return
(Reservation)getHibernateTemplate().load(Reservati
on .class,

orderId) public void
saveReservation (Reservation r)
getHibernateTemplate().saveOrUpdate(r)
public void remove(Reservation
Reservation) getHibernateTemplate().del
ete(r)
40
Hibernate DAO (contd)
public Reservation findReservations(Room
room) List list getHibernateTemplate().f
ind( "from Reservation reservation
where reservation.resource ?
order by reservation.start",
instrument) return (Reservation)
list.toArray(new Reservationlist.size())
41
Hibernate DAO (contd)
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
gt rangeStart and r.start lt rangeEnd )
query.setDate("rangeStart", range.getStartDate()
query.setDate("rangeEnd",
range.getEndDate()) return
query.list() ) return
(Reservation) list.toArray(new
Reservationlist.size())
42
Hibernate Example
ltbean id"sessionFactory" class"org.springframewo
rk.orm.hibernate.LocalSessionFactoryBean"gt
ltproperty name"dataSource"gtltref
bean"dataSource"/gtlt/propertygt ltproperty
name"mappingResources"gt ltlistgt
ltvaluegtcom/jensenp/Reservation/Room.hbm.xmllt/value
gt ltvaluegtcom/jensenp/Reservation/Reservati
on.hbm.xmllt/valuegt ltvaluegtcom/jensenp/Rese
rvation/Resource.hbm.xmllt/valuegt lt/listgt
lt/propertygt ltproperty name"hibernatePrope
rties"gt ltpropsgt ltprop
key"hibernate.dialect"gthibernate.dialectlt/prop
gt ltprop key"hibernate.hbm2ddl.auto"gthib
ernate.hbm2ddl.auto lt/propgt
ltprop key"hibernate.show_sql"gthibernate.show_sq
llt/propgt lt/propsgt lt/propertygt
lt/beangt ltbean idreservationDao"
class"com.jensenp.Reservation.ReservationDaoImpl"
gt ltproperty name"sessionFactory"gtltref
bean"sessionFactory"/gt lt/propertygt lt/beangt
43
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

44
Web Framework
45
DispatcherServlet

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

46
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

47
Dispatcher Servlet Configuration

• MultipartResolver
• Handling of file upload
• LocaleResolver
• Default uses HTTP accept header, cookie, or
  session

48
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

49
Controller Implementations

• CommandControllers bind parameters to data
  objects
• AbstractCommandController
• AbstractFormController
• SimpleFormController
• WizardFormController

50
Integration with Struts

• ltplug-in className"org.springframework.web.struts
  .ContextLoaderPlugIn"gt  ltset-property
  property"contextConfigLocation"
  value"/WEB-INF/spring/core/spring-advice.xml,/WEB
  -INF/spring/core/spring-dao.xml,/WEB-INF/spring/co
  re/spring-email.xml,/WEB-INF/spring/core/spring-se
  rvices.xml,/WEB-INF/spring/core/spring-tasks.xml,/
  WEB-INF/spring/core/spring-webservices.xml" /gt
• lt/plug-ingt

51
Integration with Struts

• ltbean id"CispWebService" class"com.bt.bbv.core.u
  til.webservices.WebServiceProxyFactoryBean"gt
• lt/propertygt- ltproperty name"servicePrefix"gt
•   ltvaluegtCISPlt/valuegt  
• lt/propertygt ltproperty name"wsdlDocumentUrl"gt 
• ltvaluegtclasspathcom/btexact/cisp/api/CispApiEJB.
  wsdllt/valuegt
• lt/propertygt- ltproperty name"serviceInterface"gt
  ltvaluegtcom.bt.bbv.core.service.cisp.webservice.Cis
  pApiEJBPortlt/valuegt
• ltproperty name"serviceName"gtltvaluegtCispApiEJBlt/va
  luegt
• lt/propertygt ltproperty name"portName"gt 
  ltvaluegtCispApiEJBPortlt/valuegt
• lt/propertygt ltproperty name"portInterface"gtltval
  uegtcom.btexact.cisp.api.CispApiEJBPortlt/valuegtlt/pr
  opertygt
• lt/beangt

52
Integration with LDAP

• ltpublic class TraditionalPersonDaoImpl implements
  PersonDao
• public List getAllPersonNames()
• Hashtable env new Hashtable()
• env.put(Context.INITIAL_CONTEXT_FACTORY,
  "com.sun.jndi.ldap.LdapCtxFactory")
• env.put(Context.PROVIDER_URL,
  "ldap//localhost389/dcexample,dccom")
• DirContext ctx new InitialDirContext(env)
  
• catch (NamingException e)
• throw new RuntimeException(e)

53
Integration with EJB

• ltbean id"myComponent class"org.springframework.
  ejb.access.LocalStatelessSessionProxyFactoryBean"gt
  
• ltproperty name"jndiName" value"ejb/myBean"/gt
  ltproperty name"businessInterface"
  value"com.mycom.MyComponent"/gt lt/beangt

54
References

• Springs homepage http//www.springframework.org
• Introducing the Spring Framework by Rod
  Johnson http//theserverside.com/news/thread.jsp?
  thread_id21893
• Inversion of control containers and dependency
  injection by Martin Fowler http//www.martinfowl
  er.com/articles/injection.html
• AOP Alliance http//aopalliance.sourceforge.net