Spring ppt

Introduction to the
Spring Framework
By Mumbai Academics

Advantages of Spring Framework Architecture
There are many advantages of Spring Framework. They are as
follows:
 Lightweight: Spring framework is lightweight because of its
POJO implementation. The Spring Framework doesn't force
the programmer to inherit any class or implement any
interface. That is why it is said non-invasive, Enable you to
write powerful, scalable applications using POJOs.
 Easy to develop JavaEE application: The Dependency
Injection feature of Spring Framework and it support to
various frameworks makes the easy development of JavaEE
application.
 Easy to test: The Dependency Injection makes easier to
test the application. The EJB or Struts application require
server to run the application but Spring framework doesn't
require server.

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Loose Coupling: The Spring applications are loosely
coupled because of dependency injection and handles
injecting dependent components without a component
knowing where they came from (IoC).
Powerful abstraction: It provides powerful abstraction to
JavaEE specifications such as JMS, JDBC, JPA and JTA.
Declarative support: It provides declarative support for
caching, validation, transactions and formatting.
Portable :can use server-side in web/ejb app, client-side in
swing app, business logic is completely portable.
Cross-cutting behavior : Resource Management is crosscutting concern, easy to copy-and-paste everywhere.

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Configuration information: Spring provides one consistent
way of configuring everything, separate configuration from
application logic, varying configuration.
Lifecycle : Responsible for managing all your application
components, particularly those in the middle tier container
sees components through well-defined lifecycle: init(),
destroy()

Spring
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A popular and stable Java application framework for
enterprise development
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Ubiquitous for Java development
Well established in enterprise Java apps
Time tested and proven reliable

A primary purpose is to reduce dependencies and
even introduce negative dependencies
 Different from almost every other framework out
there
 Part of the reason it has been adopted so quickly
 Spring code base is proven to be well structured
(possibly the best)
 139 packages
 No dependency cycles

Spring
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A lightweight framework that addresses each tier in a
Web application.
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Presentation layer – An MVC framework that is most similar
to Struts but is more powerful and easy to use.
Business layer – Lightweight IoC container and AOP support
(including built in aspects)
Persistence layer – DAO template support for popular ORMs
and JDBC
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Simplifies persistence frameworks and JDBC
Complimentary: Not a replacement for a persistence framework

Helps organize your middle tier and handle typical
J2EE plumbing problems.
Solutions to typical coding busywork
 JDBC ,LDAP,Web Services
Reduces code and speeds up development
Current Version is 3.0

Spring (continued)
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Do I have to use all components of Spring?
Spring is a non-invasive and portable framework that
allows you to introduce as much or as little as you
want to your application.
Promotes decoupling and reusability
POJO Based
Allows developers to focus more on reused business
logic and less on plumbing problems.
Reduces or alleviates code littering, ad hoc
singletons, factories, service locators and multiple
configuration files.
Removes common code issues like leaking
connections and more.
Built in aspects such as transaction management
Most business objects in Spring apps do not depend
on the Spring framework.

Why Did I choose Spring?
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Introduced to Spring by way of Hibernate
Spring is an open source layered Java/J2EE
application framework
The Spring Framework is licensed under the terms of
the Apache License
Originally wanted Spring to provide a way to simplify
DAO objects and provide declarative transaction
support to our non-EJB applications.
Needed a solution to loosely couple business logic in
a POJO fashion.
Wanted to build portable applications that provided
clearer separation of presentation, business, and
persistence logic.
Easily integrated with our existing frameworks
Great documentation and community support

Spring Mission Statement
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J2EE should be easier to use
It's best to program to interfaces, rather than classes. Spring
reduces the complexity cost of using interfaces to zero.
JavaBeans offer a great way of configuring applications
OO design is more important than any implementation
technology, such as J2EE
Checked exceptions are overused in Java. A framework
shouldn't force you to catch exceptions you're unlikely to be
able to recover from.
Testability is essential, and a framework such as Spring
should help make your code easier to test
Spring should be a pleasure to use
Your application code should not depend on Spring APIs
Spring should not compete with good existing solutions, but
should foster integration. (For example, JDO and Hibernate
are great O/R mapping solutions. Don't need to develop
another one).

Simplify your code with Spring
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Enables you to stop polluting code
No more custom singleton objects
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Beans are defined in a centralized configuration file

No more custom factory object to build and/or locate other
objects
DAO simplification
 Consistent CRUD
 Data access templates
 No more copy-paste try/catch/finally blocks
 No more passing Connection objects between methods
 No more leaked connections
POJO Based
Refactoring experience with Spring
Caution Spring is addictive!

Modules of the Spring Framework
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The Spring Framework can be considered as a collection
of frameworks-in-the-framework:
Core - Inversion of Control (IoC) and Dependency
Injection.
AOP :- These modules support aspect oriented
programming implementation where you can use Advices,
Pointcuts etc. to decouple the code.
DAO - Data Access Object support, transaction
management, JDBC-abstraction
ORM - Object Relational Mapping data access, integration
layers for JPA, JDO, Hibernate, and iBatis
MVC - Model-View-Controller implementation for webapplications
Context-This module supports internationalization (I18N),
EJB,Remote Access, Authentication and Authorization,
Remote Management like RMI,HTTP Invoker,Hessain,
Messaging Framework, Web Services, Email, Testing, …

Modules of the Spring Framework
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Expression Language:- It is an extension to the EL
defined in JSP. It provides support to setting and getting
property values, method invocation, accessing collections
and indexers, named variables, logical and arithmetic
operators, retrieval of objects by name etc.

Overview of the Spring Framework

Very loosely coupled, components widely reusable and
separately packaged.

Spring Details
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Spring allows to decouple software layers by injecting a
component’s dependencies at runtime rather than having
them declared at compile time via importing and
instantiating classes.
Spring provides integration for J2EE services such as EJB,
JDBC, JNDI, JMS, JTA. It also integrates several popular
ORM toolkits such as Hibernate and JDO and assorted
other services as well.
One of the highly touted features is declarative transactions,
which allows the developer to write transaction-unaware
code and configure transactions in Spring config files.

Spring Details
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Spring is built on the principle of unchecked exception
handling. This also reduces code dependencies between
layers. Spring provides a granular exception hierarchy for
data access operations and maps JDBC, EJB, and ORM
exceptions to Spring exceptions so that applications can get
better information about the error condition.
With highly decoupled software layers and programming to
interfaces, each layer is easier to test. Mock objects is a
testing pattern that is very useful in this regard.

Spring Solutions
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Solutions address major J2EE problem areas:
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Web application development (MVC)
Enterprise Java Beans (EJB, JNDI)
Database access (JDBC, iBatis, ORM)
Transaction management (JTA, Hibernate, JDBC)
Remote access (Web Services, RMI)

Each solution builds on the core architecture
Solutions foster integration, they do not re-invent
the wheel

How to Start Using Spring
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create the class
create the xml file to provide the values
create the test class
Load the spring jar files
Run the test class

Load the jar files required for
spring framework
There are mainly three jar files required to run this
application.
 org.springframework.core-3.0.1.RELEASE-A
 com.springsource.org.apache.commons.logging-1.1.1
 org.springframework.beans-3.0.1.RELEASE-A

What are Lightweight Frameworks?
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Non-intrusive
No container requirements
Simplify application development
Remove re-occurring pattern code
• Productivity friendly
• Unit test friendly
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Very pluggable
Usually open source
Examples:
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Spring, Pico, Hivemind
Hibernate, IBatis, Castor
WebWork
Quartz
Sitemesh

Spring IoC + AOP
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IoC container
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Setter based and constructor based dependency injection
Portable across application servers
Promotes good use of OO practices such as programming
to interfaces.
Beans managed by an IoC container are reusable and
decoupled from business logic

AOP
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Spring uses Dynamic AOP Proxy objects to provide crosscutting services
Reusable components
Aopalliance support today
Integrates with the IoC container
AspectJ support in Spring 1.1

Inversion of Control
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Dependency injection
 Beans define their dependencies through
constructor arguments or properties
 The container provides the injection at runtime
Decouples object creators and locators from
application logic
Easy to maintain and reuse
Testing is easier
Useful for separating dao and business layer
Useful for separating controllers and business layer
The code is more extensible, easier to read, and
modules/layers can easily be replaced

Non-IoC / Dependency Injection

Non-IoC Service Object
public class OrderServiceImpl implements
IOrderService {
public Order saveOrder(Order order) throws
OrderException{
try{
// 1. Create a Session/Connection object
// 2. Start a transaction
// 3. Lookup and invoke one of the methods in a
// DAO and pass the Session/Connection object.
// 4. Commit transaction
}catch(Exception e){
// handle e, rollback transaction,
//cleanup, // throw e
}finally{
//Release resources and handle more exceptions
}

}

IoC Service Object

public class OrderSpringService
implements IOrderService {
IOrderDAO orderDAO;
public Order saveOrder(Order order)
throws OrderException{
// perform some business logic…
return orderDAO.saveNewOrder(order);
}
public void setOrderDAO(IOrderDAO
orderDAO) {
this.orderDAO = orderDAO;
}
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Program to interfaces for your bean dependencies!

Spring Bean Definition

Typical java bean with a unique id
 In spring there are basically two types
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 Singleton
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One instance of the bean created and
referenced each time it is requested

 Prototype

(non-singleton)

New bean created each time
 Same as new ClassName()
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Beans are normally created by Spring
as late as possible

Spring Bean Definition
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The bean class is the actual implementation of the
bean being described by the BeanFactory.
Bean examples – DAO, DataSource, Transaction
Manager, Persistence Managers, Service objects, etc
Spring config contains implementation classes while
your code should program to interfaces.
Bean behaviors include:
 Singleton or prototype
 Autowiring
 Initialization and destruction methods
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init-method
destroy-method

Beans can be configured to have property values set.
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Can read simple values, collections, maps, references to
other beans, etc.

What is a bean definition?
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Defines a bean for Spring to manage
 Key
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attributes

class (required): fully qualified java class name
id: the unique identifier for this bean
configuration: (singleton, init-method, etc.)
constructor-arg: arguments to pass to the constructor at
creation time
property: arguments to pass to the bean setters at
creation time
Collaborators: other beans needed in this bean (a.k.a
dependencies), specified in property or constructor-arg

Typically defined in an XML file

Simple Spring Bean Example
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<bean id=“orderBean” class=“example.OrderBean”
init-method=“init”>
<property
name=“minimumAmountToProcess”>10</property>
<property name=“orderDAO”>
<ref bean=“orderDAOBean”/>
</property>
</bean>

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public class OrderBean implements IOrderBean{
…
public void
setMinimumAmountToProcess(double d){
this. minimumAmountToProcess = d;
}
public void setOrderDAO(IOrderDAO odao){
this.orderDAO = odao;
}
}

Spring BeanFactory
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BeanFactory is core to the Spring framework
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Lightweight container that loads bean definitions and
manages your beans.
Configured declaratively using an XML file, or files, that
determine how beans can be referenced and wired together.
Knows how to serve and manage a singleton or prototype
defined bean
Responsible for lifecycle methods.
Injects dependencies into defined beans when served

Avoids the use of singletons and factories
Spring uses a BeanFactory to create,
manage and locate “beans” which are
basically instances of a class
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usage is an XML bean factory which
allows configuration via XML files

Spring ApplicationContext

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A Spring ApplicationContext allows you to get access
to the objects that are configured in a BeanFactory in
a framework manner.
ApplicationContext extends BeanFactory
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Several ways to configure a context:
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Adds services such as international messaging capabilities.
Add the ability to load file resources in a generic fashion.
XMLWebApplicationContext – Configuration for a web
application.
ClassPathXMLApplicationContext – standalone XML
application context
FileSystemXmlApplicationContext

Allows you to avoid writing Service Locators

Configuring an XMLWebApplicationContext
<context-param>
<param-name>contextConfigLocation</paramname>
<param-value>
/WEB-INF/applicationContext.xml
</param-value>
</context-param>
<listener>
<listener-class>
org.springframework.web.context.ContextLoader
Listener
</listener-class>
</listener>

Configuring an XMLWebApplicationContext
<context-param>
<param-name>contextConfigLocation</paramname>
<param-value>
/WEB-INF/applicationContext.xml
</param-value>
</context-param>
<servlet>
<servlet-name>context</servlet-name>
<servlet-class>
org.springframework.web.context.ContextLoader
Servlet
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>

Spring AOP
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Framework that builds on the aopalliance interfaces.
Aspects are coded with pure Java code. You do not
need to learn pointcut query languages that are
available in other AOP implementations.
Separates the core business code from the aspects
we wrap around it: security, transaction management,
monitering,logging…
Spring aspects can be configured using its own IoC
container.
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Objects obtained from the IoC container can be
transparently advised based on configuration

Spring AOP has built in aspects such as providing
transaction management, performance monitoring
and more for your beans
Spring AOP is not as robust as some other
implementations such as AspectJ.
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However, it does support common aspect uses to solve

Spring AOP
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Attempts to separate concerns, increase
modularity, and decrease redundancy
 Separation
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Break up features to minimize overlap

 Don’t
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of Concerns (SoC)

Repeat Yourself (DRY)

Minimize code duplication

 Cross-Cutting
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Concerns

Program aspects that affect many others (e.g. logging)

AspectJ is the top AOP package

Spring AOP
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Supports the following advices:
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method before
method after returning
throws advice
around advice (uses AOPAlliance MethodInterceptor directly)

Spring allows you to chain together interceptors and
advice with precedence.
Aspects are weaved together at runtime. AspectJ uses
compile time weaving.
Spring AOP also includes advisors that contain advice
and pointcut filtering.
ProxyFactoryBean – sources AOP proxies from a Spring
BeanFactory
IoC + AOP is a great combination that is non-invasive
Through AOP, we add transversal functionalities to
objects (ie not directly related to the code it contains)

2. Spring principles: AOP
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Without AOP

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With AOP

2. Spring principles: AOP
Useful for automatic handling of transaction
with Hibernate
 Useful for Acegi (automatic credentials
checking before executing some methods)
 Code smaller, easier to read (not polluted
by transversal aspects not directly relevant)
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Consistent Abstract Classes for DAO Support
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Extend your DAO classes with the proper xxxDAOSupport class
that matches your persistence mechanism.
JdbcDaoSupport
Super class for JDBC data access objects.
 Requires a DataSource to be set, providing a JdbcTemplate based
on it to subclasses.
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HibernateDaoSupport
Super class for Hibernate data access objects.
 Requires a SessionFactory to be set, providing a
HibernateTemplate based on it to subclasses.
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JdoDaoSupport
Super class for JDO data access objects.
 Requires a PersistenceManagerFactory to be set, providing a
JdoTemplate based on it to subclasses.
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SqlMapDaoSupport
Supper class for iBATIS SqlMap data access object.
 Requires a DataSource to be set, providing a SqlMapTemplate
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Spring DAO Templates
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Built in code templates that support JDBC, Hibernate,
JDO, and iBatis SQL Maps
Simplifies data access coding by reducing redundant
code and helps avoid common errors.
Alleviates opening and closing connections in your
DAO code.
No more ThreadLocal or passing Connection/Session
objects.
Transaction management is handled by a wired bean
You are dropped into the template with the resources
you need for data access – Session,
PreparedStatement, etc.
Code only needs to be implemented in callback
methods.
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doInXXX(Object)

Optional separate JDBC framework

Ex: Code without a template
public class OrderHibernateDAO implements IOrderDAO {
public Order saveOrder(Order order) throws
OrderException{
Session s = null;
Transaction tx = null;
try{
s = ... // get a new Session object
tx = s.beginTransaction();
s.save(order);
tx.commit();
} catch (HibernateException he){
// log, rollback, and convert to OrderException
} catch (SQLException sqle){
// log, rollback, and convert to OrderException
} finally {
s.close(); // needs a try/catch block
}
return order;
}

Ex: Spring DAO Template Example
public class OrderHibernateDAO extends HibernateDaoSupport
implements IOrderDAO {
...
public Order saveOrder(final Order order) {
return (Order) getHibernateTemplate().execute(new
HibernateCallback() {
public Object doInHibernate(Session session)
throws HibernateException, SQLException {
session.save(order);
return order;
}
});
}
...
}

Consistent Exception Handling
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Spring has it’s own exception handling hierarchy for DAO logic.

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No more copy and pasting redundant exception logic!

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Exceptions from JDBC, or a supported ORM, are wrapped up
into an appropriate, and consistent, DataAccessException and
thrown.

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This allows you to decouple exceptions in your business logic.

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These exceptions are treated as unchecked exceptions that you
can handle in your business tier if needed. No need to try/catch
in your DAO.

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Define your own exception translation by subclassing classes
such as SQLErrorCodeSQLExceptionTranslator

Spring and Testing

Easier test driven development (TDD)
 Integration testing
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use a standalone Spring configuration
with mock objects for testing.
 Consider XMLApplicationContext or
FileSystemApplicationContext.
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Unit testing
 Allows

you to test outside the container
without using the Spring container.

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Easy to test POJOs

MVC Framework
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Clear separation of roles: controller, validator, form object,
Dispatch servlet, View resolver, …
Extensible and adaptable
Several views of a result (pdf, excel, html, …)
Can be wired (possible to use transparently the IoC pattern).
Spring Annotation Based Controllers
Spring 2.5 introduced support for annotation based MVC
controllers. @RequestMapping, @RequestParam,
@ModelAttribute are some of the annotations provided for this
implementation.

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Can be used with other frameworks: JSF, Struts,
Tapestry, Webwork
Completely transparent: no need to change anything in
what is done by these other frameworks

Benefits of the Spring Web
MVC Framework
The Spring Web MVC Framework is a robust, flexible, and
well-designed framework for rapidly developing web
applications using the MVC design pattern.The benefits
achieved from using this Spring module are similar to
those you get from the rest of the Spring Framework
Easier testing—This is a common theme you will find
across all the Spring classes.The fact that most of Spring’s
classes are designed as JavaBeans enables you to inject
test data using the setter methods of these classes. Spring
also provides mock classes to simulate Java HTTP objects
(HttpServletRequest, for example), which makes unit
testing of the web layer much simpler.

MVC Framework
Bind directly to business objects—Spring MVC does not
require your business (model) classes to extend any
special classes; this enables you to reuse your business
objects by binding them directly to the HTML forms fields. In
fact, your controller classes are the only ones that are
required to extend Spring classes (or implement a Spring
controller interface).
Clear separation of roles—Spring MVC nicely separates
the roles played by the various components that make up
this web framework. For example, when we dis-cuss
concepts such as controllers, command objects, and
validators, you will begin to see how each component
plays a distinct role.

MVC Framework
Simple but powerful tag library—Spring's tag library is
small, straightforward, but powerful. For example. Spring
uses the JSP expression language (EL) for arguments
to the <spring :bind> tag.
Web Flow—This module is a subproject and is not bundled
with the Spring core distribution. It is built on top of Spring
MVC and adds the capability to easily write wizard like
web applications that span across several HTTP requests
(an online shopping cart, for example).

MVC Framework
View technologies and web frameworks—Although we
are using JSP as our view technology. Spring supports
odier view technologies as well, such as Apache Velocity
and FreeMarker.This is a powerful concept because
switching from JSP to Velocity is a matter of configuration. Furthermore, Spring provides integration support for
Apache Struts.
■ Lighter-weight environment—As I mentioned in die
previous chapter. Spring enables you to build enterpriseready applications using FOJOs; the environment
setup can be simpler and less expensive because you
could develop and deploy your application using a lighterweight servlet container.

Features of Spring Web MVC
Spring's web module provides a wealth of unique web support
features, including:
 Clear separation of roles - controller, validator, command
object, form object, model object, DispatcherServlet, handler
mapping, view resolver, etc. Each role can be fulfilled by a
specialized object.
 Powerful and straightforward configuration of both framework
and application classes as JavaBeans, including easy
referencing across contexts, such as from web controllers to
business objects and validators.
 Adaptability, non-intrusiveness. Use whatever controller
subclass you need (plain, command, form, wizard, multi-action,
or a custom one) for a given scenario instead of deriving from a
single controller for everything.
 Reusable business code - no need for duplication. You can use
existing business objects as command or form objects instead of
mirroring them in order to extend a particular framework base


Customizable

locale and theme resolution, support for JSPs
with or without Spring tag library, support for JSTL, support for
Velocity without the need for extra bridges, etc.
 A simple yet powerful JSP tag library known as the Spring tag
library that provides support for features such as data binding
and themes. The custom tags allow for maximum flexibility in
terms of markup code. For information on the tag library
descriptor.
 A JSP form tag library, introduced in Spring 2.0, that makes
writing forms in JSP pages much easier. For information on the
tag library descriptor.
 Beans whose lifecycle is scoped to the current HTTP request
or HTTP Session. This is not a specific feature of Spring MVC
itself, but rather of the WebApplicationContext container(s) that
Spring MVC uses. These bean scopes are described in detail in
the section entitled.


Customizable binding and validation - type mismatches as
application-level validation errors that keep the offending value,
localized date and number binding, etc instead of String-only
form objects with manual parsing and conversion to business
objects.
 Customizable handler mapping and view resolution - handler
mapping and view resolution strategies range from simple URLbased configuration, to sophisticated, purpose-built resolution
strategies. This is more flexible than some web MVC
frameworks which mandate a particular technique.
 Flexible model transfer - model transfer via a name/value Map
supports easy integration with any view technology.
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Working Of MVC Framework

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The Spring web MVC framework provides model-viewcontroller architecture and ready components that can be
used to develop flexible and loosely coupled web applications.
The MVC pattern results in separating the different aspects of
the application (input logic, business logic, and UI logic), while
providing a loose coupling between these elements.
The Model encapsulates the application data and in general
they will consist of POJO.
The View is responsible for rendering the model data and in
general it generates HTML output that the client's browser
can interpret.
The Controller is responsible for processing user requests
and building appropriate model and passes it to the view for
rendering.

The DispatcherServlet

The Spring Web model-view-controller (MVC) framework is
designed around a DispatcherServlet that handles all the
HTTP requests and responses. The request processing
workflow of the Spring Web MVC DispatcherServlet is
illustrated in the following diagram:

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Following is the sequence of events corresponding to an
incoming HTTP request to DispatcherServlet:
After receiving an HTTP request, DispatcherServlet consults
the HandlerMapping to call the appropriate Controller.
The Controller takes the request and calls the appropriate
service methods based on used GET or POST method. The
service method will set model data based on defined business
logic and returns view name to the DispatcherServlet.
The DispatcherServlet will take help from ViewResolver to
pickup the defined view for the request.
Once view is finalized, The DispatcherServlet passes the
model data to the view which is finally rendered on the
browser.

All the above mentioned components ie. HandlerMapping, Controller and ViewResolver are parts
ofWebApplicationContext which is an extension of the plain ApplicationContext with some
extra features necessary for web applications.

Even More Spring Components
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JavaMail helpers
Many ORM tools are supported: Hibernate, JDO, Apache
OJB, iBATIS
Templates using IoC to reduce the amount of code in the
DAO objects
Scheduling support via Quartz
Convenience implementation classes for
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Remoting support – JAXRPC, RMI, Hessian, and Burlap

EJB support for easier access.
Acegi Security System for Spring
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http://acegisecurity.sourceforge.net/
Very good framework!

Eclipse Plugin – Spring IDE for Eclipse
Coming soon
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JMS implementation classes
JMX support

Spring ppt

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