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 API’s.

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 ClassPathXmlApplicationContext("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 <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"/>

23. 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">

24. 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”

25. Web Initialization • Web applications may use ContextLoaderListener to initialize Spring web.xml <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> Automatically done by Spring DispatcherServlet

26. 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>

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 <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>

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 <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>

34. 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" /> 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 <bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean" lazy-init="default" autowire="default" dependency-check="default"> <property name="jndiName"> <value>com.bt.bbv.r1oss</value> </property> </bean> <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate" lazy-init="default" autowire="default" dependency-check="default"> <property name="dataSource"> <ref bean="dataSource" /> </property> </bean> </beans>

39. 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); }

40. 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()]);

41. 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()]); } }

42. 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>

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 • <plug-in className="org.springframework.web.struts.ContextLoaderPlugIn"><set-propertyproperty="contextConfigLocation" value="/WEB-INF/spring/core/spring-advice.xml,/WEB-INF/spring/core/spring-dao.xml,/WEB-INF/spring/core/spring-email.xml,/WEB-INF/spring/core/spring-services.xml,/WEB-INF/spring/core/spring-tasks.xml,/WEB-INF/spring/core/spring-webservices.xml" /> • </plug-in>