Spring3.0 - Core

New features of Spring 3.0

Ø  Spring Expression Language

Ø  IoC enhancements/Java based bean metadata

Ø  General-purpose type conversion system and field formatting system

Ø  Object to XML mapping functionality (OXM) moved from Spring Web Services project

Ø  Comprehensive REST support

Ø  @MVC additions

Ø  Declarative model validation

Ø  Early support for Java EE 6

Ø  Embedded database support

2.5.1 Core APIs updated for Java 5

Ø  BeanFactory interface returns typed bean instances as far as possible:

                      T getBean(Class<T> requiredType)

                      T getBean(String name, Class<T> requiredType)

                      Map<String, T> getBeansOfType(Class<T> type) 

Ø  Spring's TaskExecutor interface now extends java.util.concurrent.Executor:

                     extended AsyncTaskExecutor supports standard Callables with Futures

Ø  New Java 5 based converter API and SPI:

                      stateless ConversionService and Converters

                      superseding standard JDK PropertyEditors

Advantages of autowiring.

Ø  It can significantly reduce the volume of configuration required.

Ø  It can cause configuration to keep itself up to date as your objects evolve. For example, if you need to add an additional dependency to a class, that dependency can be satisfied automatically without the need to modify configuration. Thus there may be a strong case for autowiring during development, without ruling out the option of switching to explicit wiring when the code base becomes more stable.

Disadvantages of autowiring:

Ø  Spring is careful to avoid guessing in case of ambiguity which might have unexpected results, the relationships between Spring-managed objects are no longer documented explicitly.

Ø  Wiring information may not be available to tools that may generate documentation from a Spring container.

Bean scopes

Ø  singleton

Ø  prototype

Ø  request

Ø  session

Ø  global-session- if not portlet based application it will act like session

Dependency check modes

Ø  none- no dependency checking

Ø  simple- To check look for primitive types and collections if not unsatisfieddependencyexception will be thrown

Ø  objects- To check for objects  if not unsatisfieddependencyexception will be thrown

Ø  all- of all types primitive,objects,collection and so on.

           <bean id="CustomerBean" class="com.mkyong.common.Customer"                                           dependency-check="simple">

Creating our own Annotation based bean

Ø  @Required  - Helps to ensure the autowire object should be instantiated

      empty interface should be declared with

Ø  @Retention(RetentionPolicy.RUNTIME)

Ø  @Target(ElementType.MEthod)

Ø  @{empty interface name} on autowiring the element [ provide above the setter  method]

Bean instantiation through class

Ø  @Configuration - Provided for class that is to be configured as config file

Ø  @Bean(name="ab") - Provided for autowired bean class [instead of giving in <bean > tag we can use it like this]

Ø  AnnotationConfigApplicationContext(AppCofg.class) -
Helps to call the configuration class

postconstructor preconstructor

Ø  @PostConstruct

Ø  @PreConstruct

Annotated to call and after the method in the class

Pre-Post callback methods

Ø  int-method - called after the constructor & @postconstruct is called

Ø  destroy-method - called after @preconstruct is called [ like finally block]

interfaces - intializingbean,disposablebean

Ø  initializingbean- afterPropertySet method has to be implemented

Ø  disposblebean - destroy method should be implemented