Spring training

Spring Training TechFerry Infotech Pvt. Ltd. (http://www.techferry.com/)

Conversations Introduction to Spring Concepts: Annotations, MVC, IOC/DI, Auto wiring Spring Bean/Resource Management Spring MVC, Form Validations. Unit Testing Spring Security – Users, Roles, Permissions. Code Demo CRUD using Spring, Hibernate, MySQL. Spring security example. REST/jQuery/Ajax example

Spring - Introduction Exercise: What do we need in an enterprise application? Database Access, Connection Pools? Transactions? Security, Authentication, Authorization? Business Logic Objects? Workflow/Screen Flow? Messaging/emails? Service Bus? Concurrency/Scalability? Can somebody wire all the needed components? Do we have to learn everything before we can start?

Hello Spring Spring is potentially a one-stop shop, addressing most infrastructure concerns of typical web applications so you focus only on your business logic. Spring is both comprehensive and modular use just about any part of it in isolation, yet its architecture is internally consistent. maximum value from your learning curve.

What is Spring? Open source and lightweight web-application framework Framework for wiring the entire application Collection of many different components Reduces code and speeds up development Spring is essentially a technology dedicated to enabling you to build applications using POJOs.

Why Spring? Spring Enables POJO Programming Application code does not depend on spring API’s Dependency Injection and Inversion of Control simplifies coding Promotes decoupling and re-usability Features: Lightweight Inversion of Control (IoC) Aspect oriented (AOP) MVC Framework Transaction Management JDBC Ibatis / Hibernate

What else Spring do? Spring Web Flow Spring Integration Spring Web-Services Spring MVC Spring Security Spring Batch Spring Social Spring Mobile ... and let it ever expand ...

Inversion of Control/Dependency Injection "Don't call me, I'll call you." IoC moves the responsibility for making things happen into the framework Eliminates lookup code from within the application Loose coupling, minimum effort and least intrusive mechanism

IOC/DI Non IOC Example: class MovieLister... private MovieFinder finder; public MovieLister() { finder = new MovieFinderImpl(); } public interface MovieFinder { List findAll(); } class MovieFinderImpl ... { public List findAll() { ... } }

IOC/DI IoC Example: DI exists in major two variants: Setter Injection public class MovieLister { private MovieFinder movieFinder; public void setMovieFinder(MovieFinder movieFinder) { this.movieFinder = movieFinder; } } Constructor Injection public class MovieLister{ private MovieFinder movieFinder; public MovieLister(MovieFinder movieFinder) { this.movieFinder = movieFinder; } }

Code Demo .... Annotations: @Component, @Service, @Repository Annotation: @Autowire web.xml - Context loader listener to scan components <context:annotation-config /> <context:component-scan base-package="..." /> Spring Bean Management

Bean Scopes singleton Scopes a single bean definition to a single object instance per Spring IoC container. prototype Scopes a single bean definition to any number of object instances. request Scopes a single bean definition to the lifecycle of a single HTTP request. session Scopes a single bean definition to the lifecycle of a HTTP Session. global session Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a portlet context.

Prototype Beans Use @Scope("prototype") Caution: dependencies are resolved at instantiation time. It does NOT create a new instance at runtime more than once.

Bean Scopes Contd.. As a rule of thumb, you should use the prototype scope for all beans that are stateful, while the singleton scope should be used for stateless beans. RequestContextListener is needed in web.xml for request/session scopes. Annotation:@Scope("request") @Scope("prototype") Homework: Singleton bean referring a prototype/request bean? @Qualifier, Method Injection. Hate Homework? Stick to stateless beans. :)

Wiring Beans no No autowiring at all. Bean references must be defined via a ref element. This is the default. byName Autowiring by property name. byType Allows a property to be autowired if there is exactly one bean of the property type in the container. If there is more than one, a fatal exception is thrown. constructor This is analogous to byType , but applies to constructor arguments. autodetect Chooses constructor or byType through introspection of the bean class.

Homework :) What wiring method is used with @Autowire annotation? Other annotations you may find useful: @Required @Resource Also review the Spring annotation article: http://www.techferry.com/articles/spring-annotations.html

MVC - Model View Controller Better organization and code reuse. Separation of Concern Can support multiple views

Spring MVC Code Demo .... Annotations: @Controller, @RequestMapping, @ModelAttribute, @PathVariable Spring DispatcherServlet config - just scan controllers web.xml - Context loader listener to scan other components ResourceBundleMessageSource and <spring:message> tag Reference: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html @RequestMapping Details Handler method arguments and Return Types

Pre-populate Model and Session Objects @Controller @RequestMapping("/owners/{ownerId}/pets/{petId}/edit") @SessionAttributes("pet") public class EditPetForm { @ModelAttribute("types") public Collection<PetType> populatePetTypes() { return this.clinic.getPetTypes(); } @RequestMapping(method = RequestMethod.POST) public String processSubmit(@ModelAttribute("pet") Pet pet, BindingResult result, SessionStatus status) { new PetValidator().validate(pet, result); if (result.hasErrors()) { return "petForm"; }else { this.clinic.storePet(pet); status.setComplete(); return "redirect:owner.do?ownerId=" + pet.getOwner().getId(); } } }

Form Validation Code Demo ... BindingResult Validator.validate() <form:errors> tag Alternative: Hibernate Validator can also be used for annotation based validation. public class PersonForm { @NotNull @Size(max=64) private String name; @Min(0) private int age; } @RequestMapping("/foo") public void processFoo(@Valid Foo foo) { /* ... */ }

Unit Testing @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = { "/spring-servlet-test.xml" }) @Test Other useful Annotations: @DirtiesContext @ExpectedException(SomeBusinessException.class) @Timed(millis=1000) @NotTransactional

Spring Security Code Demo ... <sec:authorize> tag Annotations: @PreAuthorize applicationContext-security.xml DB Schema: Users, Authorities

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