The Spring FrameworkPaul Bakker

Goals

An introduction

Not pointing a winner

Outline

• History and overview

• Dependency Injection

• AOP

• Module deep dive

• Testing

History

Founded by Rod Johnson

First introduced in his book “J2EE Design & Development”

Modules

Why Dependency Injection?

H o w w o u l d y o u t e s t t h i s m e t h o d ?

publicdoublecalculateTotalPrice(){ProductServiceproductService=newProductService();Listproducts=productService.getProducts();

//iterateproductsandsumprices

returntotal;}

productService.getProducts()

Database

publicdoublecalculateTotalPrice(){ProductServiceproductService=newProductService();Listproducts=productService.getProducts();

//iterateproductsandsumprices

returntotal;}

publicvoidtestCalculateTotalPrice(){Calculatorcalc=newCalculator();assertEquals(150,calc.calculateTotalPrice());

}

Throws Exception...

publicCalculator(ProductServiceproductService){this.productService=productService;

}

publicdoublecalculateTotalPrice(){Listproducts=productService.getProducts();

//iterateproductsandsumprices

returntotal;}

publicvoidtestCalculateTotalPrice(){Calculatorcalc=newCalculator(newProductServiceMock());

assertEquals(150,calc.calculateTotalPrice());}

Program to interfaces

not to implementations

Inversion of Control

A container manages dependencies

ProductService Calculator

IoC Container

Configuring a container

ProductServicepService=newProductServiceImpl();Calculatercalc=newCalculator(pService);

//initotherinstances

This will be a lot of work however...

Configuration using XML

<beanid="productService"class="services.ProductServiceImpl"/>

<beanid="calculator"class="calc.Calculator"><constructor‐argindex="0"ref="productService"/></bean>

Spring version 1 way

Configuration using annotations

@Stateless(name="ProductEJB")publicclassProductBean{publicProductBean(){}}

JEE 5 way

@EJBShoppingBasketBeanshoppingBasket;

Spring annotations

• Spring can now be configured using annotations

• Use annotations for component declarations

• Use XML for container wide configuration

Annotation example

@ServicepublicclassSimpleMovieLister{privateMovieFindermovieFinder;@AutowiredpublicSimpleMovieLister(MovieFindermovieFinder){this.movieFinder=movieFinder;}}

AutoWiring

• Don’t explicitly wire dependencies

• Just declare beans

Autowiring qualifiers<beanclass="example.SimpleMovieCatalog"><qualifiervalue="main"/></bean>

<beanclass="example.SimpleMovieCatalog"><qualifiervalue="action"/></bean>

@Autowired@Qualifier("main")privateMovieCatalogmovieCatalog;

Aspect Oriented Programming

• Used internally by Spring;

• e.g. Transaction Management

• AspectJ integration for easy AOP on your Spring beans

2 minute AOP intro

public void myMethod(..) { //do something}

public void trace(..) { //log something}

Class A

Before

Module deep dive

Spring DAOSpring DAO

JdbcTemplate

intcountOfActorsNamedJoe=this.jdbcTemplate.queryForInt("selectcount(0)fromt_actorswherefirst_name=?",newObject[]{"Joe"});

JdbcTemplate

this.jdbcTemplate.update("deletefromactorwhereid=?",newObject[]{newLong.valueOf(actorId)});

SimpleJdbcTemplate

Stringsql="selectid,first_name,last_namefromT_ACTORwhereid=?";

ParameterizedRowMapper<Actor>mapper=newParameterizedRowMapper<Actor>(){publicActormapRow(ResultSetrs,introwNum)throwsSQLException{Actoractor=newActor();actor.setId(rs.getLong("id"));actor.setFirstName(rs.getString("first_name"));actor.setLastName(rs.getString("last_name"));returnactor;}};

returnthis.simpleJdbcTemplate.queryForObject(sql,mapper,id);

Exceptions

• Spring wraps every jdbc exception

• Same structure for ORM exceptions

• Handle specific database exceptions in a uniform way

• Translate checked exception to unchecked exceptions

Module deep dive

Spring ORMSpring ORM

ORM Integration

• Hibernate

• iBATIS

• JDO

• TopLink

• JPA

Session FactoryConfiguration

<beanid="mySessionFactory"class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"><propertyname="dataSource"ref="myDataSource"/><propertyname="mappingResources"><list><value>product.hbm.xml</value></list></property><propertyname="hibernateProperties"><value>hibernate.dialect=org.hibernate.dialect.HSQLDialect</value></property></bean>

Hibernate TemplateConfiguration

<beanid="myProductDao"class="product.ProductDaoImpl"><propertyname="sessionFactory"ref="mySessionFactory"/>

</bean>

Hibernate Template

publicclassHibernateProductDaoextendsHibernateDaoSupport{

publicCollectionloadProductsByCategory(Stringcategory)throwsDataAccessException,MyException{

returnthis.hibernateTemplate.find("fromtest.Productproductwhereproduct.category=?",category);}

}

Transactions

It’s just more configuration

<beanid="myTxManager"class="org.springframework.orm.hibernate3.HibernateTransactionManager"><propertyname="sessionFactory"ref="mySessionFactory"/></bean>

<aop:config><aop:pointcutid="productServiceMethods"expression="execution(*product.ProductService.*(..))"/><aop:advisoradvice‐ref="txAdvice"pointcut‐ref="productServiceMethods"/></aop:config>

<tx:adviceid="txAdvice"transaction‐manager="myTxManager"><tx:attributes><tx:methodname="increasePrice*"propagation="REQUIRED"/><tx:methodname="someOtherBusinessMethod"propagation="REQUIRES_NEW"/><tx:methodname="*"propagation="SUPPORTS"read‐only="true"/></tx:attributes></tx:advice>

<beanid="myTxManager"class="org.springframework.orm.hibernate3.HibernateTransactionManager"><propertyname="sessionFactory"ref="mySessionFactory"/></bean>

<aop:config><aop:pointcutid="productServiceMethods"expression="execution(*product.ProductService.*(..))"/><aop:advisoradvice‐ref="txAdvice"pointcut‐ref="productServiceMethods"/></aop:config>

<tx:adviceid="txAdvice"transaction‐manager="myTxManager"><tx:attributes><tx:methodname="increasePrice*"propagation="REQUIRED"/><tx:methodname="someOtherBusinessMethod"propagation="REQUIRES_NEW"/><tx:methodname="*"propagation="SUPPORTS"read‐only="true"/></tx:attributes></tx:advice>

Transaction manager

<beanid="myTxManager"class="org.springframework.orm.hibernate3.HibernateTransactionManager"><propertyname="sessionFactory"ref="mySessionFactory"/></bean>

<aop:config><aop:pointcutid="productServiceMethods"expression="execution(*product.ProductService.*(..))"/><aop:advisoradvice‐ref="txAdvice"pointcut‐ref="productServiceMethods"/></aop:config>

<tx:adviceid="txAdvice"transaction‐manager="myTxManager"><tx:attributes><tx:methodname="increasePrice*"propagation="REQUIRED"/><tx:methodname="someOtherBusinessMethod"propagation="REQUIRES_NEW"/><tx:methodname="*"propagation="SUPPORTS"read‐only="true"/></tx:attributes></tx:advice>

Pointcut and Advisor

<beanid="myTxManager"class="org.springframework.orm.hibernate3.HibernateTransactionManager"><propertyname="sessionFactory"ref="mySessionFactory"/></bean>

<aop:config><aop:pointcutid="productServiceMethods"expression="execution(*product.ProductService.*(..))"/><aop:advisoradvice‐ref="txAdvice"pointcut‐ref="productServiceMethods"/></aop:config>

<tx:adviceid="txAdvice"transaction‐manager="myTxManager"><tx:attributes><tx:methodname="increasePrice*"propagation="REQUIRED"/><tx:methodname="someOtherBusinessMethod"propagation="REQUIRES_NEW"/><tx:methodname="*"propagation="SUPPORTS"read‐only="true"/></tx:attributes></tx:advice>

Advice - Propagation properties

Module deep dive

Spring WEBSpring WEB

Web MVC Components

• Controllers

• View Handlers

• Validation

Controller Hierarchy

AbstractController

CommandController

FormController

WizzardController

MultiactionController

Compared to other web frameworks

• Web MVC is very simple

• It’s ‘action’ based

• Close to the request/response model

• It doesn’t have conversational state

Spring Portlets

• Web MVC for JSR-168

• Exactly the same programming model for Portlets and Servlets

• Doesn’t hide the Portlet specific flow

Testing

• Spring Mock• Integration Testing

Spring Mocks

• Mock often used objects

• Request, Response, Session, JNDI etc.

Spring integration testing

• Test Wiring

• Test DAOs

Test DAOs

• Wire beans

• Manage transactions

• Rollback transaction after each test

• Mix Hibernate and plain JDBC in one transaction

DAO test example

@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations={"daos.xml"})publicfinalclassHibernateTitleDaoTests{@AutowiredprivateHibernateTitleDaotitleDao;publicvoidtestLoadTitle()throwsException{Titletitle=this.titleDao.loadTitle(newLong(10));assertNotNull(title);}}

Closed source Spring?

The verdict

• Spring is very complete

• It’s “environment friendly”

• It helps loose coupling

• It’s much better than J2EE

Do we still need it?

• JEE 5 has a similar programming model

• Seam is a much better web framework

Where to start

• http://springframework.org

• Reference documentation

• Spring Pet store

Spring related

• Spring Webflow

• Spring security (acegi)

• Spring webservices

• Spring integration

Enjoy your evening