Spring 3.1 to 3.2 in a Nutshell - Spring I/O 2012

Spring 3.1 to 3.2
in a Nutshell
Sam Brannen
Swiftmind

Speaker Profile
• Spring & Java consultant @ Swiftmind
• Developing Java for over 14 years
• Spring Framework Core Developer
• Spring Trainer
• Lead author of “Spring in a Nutshell”

Agenda
• Major Themes in 3.x
• Environment and Profiles
• Java-based Configuration
• Testing
• Caching
• MVC and REST
• Servlet 3.0
• 3.2 Roadmap

Java EE 6 support: JPA 2.0, JSF 2.0

Major Themes in Spring 3.1
– Environment abstraction
– Java-based application configuration
– @Configuration class test support
– High-level cache API
– Customizable @MVC processing
– Flash maps and redirect attributes
– Explicit support for Servlet 3.0

Environment Abstraction
– Injectable environment abstraction API
• org.springframework.core.env.Environment

– Two core concepts
• Property Sources
• Bean Profiles

Property Source: Bean Profile:

A variety of sources: property A logical group of bean
files, system properties, definitions. Registered only if
servlet context, JNDI, etc. the profile is active.

Property Source Abstraction
– Property source

– Property resolution

– Placeholders

PropertySource(s)
– PropertySource
• a single property source

– PropertySources
• a hierarchy of PropertySource objects
• potentially varying across deployment environments

Property Resolution SPI

– org.springframework.core.env.PropertyResolver

– Environment extends PropertyResolver

Custom Placeholder Resolution

– dependent on the actual environment

– PropertySourcesPlaceholderConfigurer
supersedes PropertyPlaceholderConfigurer

Managing Property Sources
– Stand-alone code

– Web application
• Implement ApplicationContextInitializer
• Register via contextInitializerClasses context parameter in
web.xml

Accessing Properties
– By injecting the Environment

Bean Definition Profiles
– Logical grouping of bean definitions
• for activation in specific environments
• e.g., dev, staging, prod
• possibly different deployment platforms

– Configuration
• XML via <beans profile=“…”>
• Java-based configuration via @Profile

Configuring Profiles in XML
– All bean definitions

– Subset of bean definitions

Configuring Profiles in Java Config

– @Profile can also be used on components
• @Component, @Service, @Repository, etc. 26

Profile Activation Options
– programmatically

– system property

– in web.xml

– in tests via @ActiveProfiles

Activating Profiles…
programmatically

via system properties

-Dspring.profiles.active=“dev”

-Dspring.profiles.default=“common”

in web apps

in integration tests

Java Config ~= XML
– XML namespaces  @Enable*
– FactoryBeans  builders
– GenericXmlContextLoader 
AnnotationConfigContextLoader

– Not a one-to-one mapping
• Make the most of what Java has to offer
• Intuitive annotation-oriented container configuration

Typical Infrastructure Setup
– Transactions

– Scheduling

– MVC customization

– AOP

@Enable* Annotations
– Applied at the class-level on @Configuration
classes

– Roughly equivalent to their XML namespace
counterparts

@Enable* in 3.1
– @EnableTransactionManagement
– @EnableCaching
– @EnableAsync
– @EnableScheduling
– @EnableAspectJAutoProxy
– @EnableLoadTimeWeaving
– @EnableSpringConfigured
– @EnableWebMvc

Hibernate and JPA
– Hibernate LocalSessionFactoryBuilder API
• Hibernate 4 replacement for both
LocalSessionFactoryBean and
AnnotationSessionFactoryBean

– XML-free JPA configuration
• LocalContainerEntityManagerFactoryBean has a
new property
• packagesToScan: analogous to
AnnotationSessionFactoryBean

Java Configuration Example

Actually:
LocalSessionFactoryBuilder

New Testing Features in 3.1
– @Configuration class support
– Environment profile support
– SmartContextLoader
– AnnotationConfigContextLoader
– DelegatingSmartContextLoader
– Updated context cache key generation

SmartContextLoader SPI
– Supersedes ContextLoader
– Strategy for loading application contexts
– From @Configuration classes or resource
locations
– Supports environment profiles

@ContextConfiguration
accepts a new `classes` attribute...

Caching Abstraction
– Declarative caching for Spring applications
• Minimal impact on code
• Plug in various caching solutions

Caching Abstraction
– Key annotations
• @Cacheable
• @CacheEvict

Cache Key
– All method arguments used by default

– Use SpEL to select more specifically (use
class, method, or argument name)

Cache Providers (1/2)
– Cache and CacheManager SPI
• org.springframework.cache

– Cache Implementations
• EhCacheCache
• ConcurrentMapCache and
ConcurrentMapCacheFactoryBean

Cache Providers (2/2)
– CacheManager Implementations
• EhCacheCacheManager
• ConcurrentMapCacheManager
• SimpleCacheManager
• NoOpCacheManager

– Any other implementation can be plugged in
• GemFire, Coherence, etc.

Cache Configuration
– Cache namespace
• <cache:annotation-driven />
• “cacheManager” bean

@MVC 3.0 Config
– Built-in defaults
• Based on DispatcherServlet.properties

– Spring MVC namespace
• <mvc:annotation:driven>, <mvc:interceptors>, …

Java-based @MVC 3.1 Config
– Most Spring MVC configuration is in Java already
• @Controller, @RequestMapping, etc.

– Servlet 3.0 enhancements will further reduce the
need for web.xml

– XML namespace is convenient but …
• Not transparent
• Not easy to offer the right degree of customization

– … What should a Java equivalent to the MVC
namespace look like?

@EnableWebMvc
– Enables Spring MVC default configuration
• Registers components expected by the
DispatcherServlet

– Allows for configuration similar to the
Spring MVC namespace
• … and the DispatcherServlet.properties combined

A More Complete Example …
– Add component scanning for @Controllers
and other beans

Q: Where is the “Enabled”
Configuration ?!
– A: a framework-provided @Configuration class
(actually DelegatingWebMvcConfiguration)

How Do I Customize All This?
– Simply implement the WebMvcConfigurer
interface
Allows selective overriding

HandlerMethod Abstraction
– HandlerMethod
• A proper abstraction for the selected “handler” in Spring MVC

– Not just for @RequestMapping methods
• Also @InitBinder, @ModelAttribute, @ExceptionHandler
methods

– “HandlerMethod” support classes
• RequestMappingHandlerMapping
• RequestMappingHandlerAdapter
• ExceptionHandlerExceptionResolver

Path Variables in the Model
– @PathVariable arguments automatically
added to the model

These can be deleted

URI Templates in Redirect Strings
– URL templates supported in “redirect:”
strings

Expanded from model attributes,
which now include @PathVariables

URI Template Vars in Data Binding
– URI template variables used in data binding

Matching MediaTypes < @MVC 3.1
– Using the 'headers' condition

Matching MediaTypes in @MVC 3.1
– The 'consumes' and 'produces' conditions

If not matched, results in:
UNSUPPORTED_MEDIA_TYPE (415)

If not matched, results in:
NOT_ACCEPTABLE (406)

Servlet 3.0 Containers

• Tomcat 7 and GlassFish 3
– Explicitly supported

• While preserving compatibility with Servlet
2.4+

XML-free Web-app Config
• Support for XML-free web application setup
– no web.xml

• Made possible via:
– Servlet 3.0's ServletContainerInitializer
– Spring 3.1's
AnnotationConfigWebApplicationContext
– Spring 3.1’s environment abstraction

Native Servlet 3.0 in @MVC
• Asynchronous request processing

• Standard Servlet 3.0 file upload
– behind Spring's MultipartResolver abstraction

"c:" Namespace
– Shortcut for <constructor-arg>
• inline argument values
• analogous to existing "p:" namespace
– Use of constructor argument names
• recommended for readability
• debug symbols have to be available in the
application's class files

Spring 3.1 in a Nutshell
• Environment and Profiles
• Java-based Configuration and @Enable*
• Testing with @Configuration and Profiles
• Cache Abstraction
• MVC and REST Improvements
• Servlet 3.0
• c: Namespace

Build System & Source Control
• Moved from Subversion to Git(hub)
– Spring 3.1.1
– github.com/SpringSource/spring-framework

• Moving from Spring Build (i.e., Ant + Ivy) to
Gradle

• SPR-8120

Servlet 3.0/3.1 Async Requests
• Servlet 3.0/3.1 asynchronous request
processing
– Explicit support in Spring @MVC

• SPR-8517

Java EE 7
• JPA 2.1 (JSR-338)
– Building on JPA 2.0 support in Spring 3.0
– SPR-8194

• JSF 2.2 (JSR-344)
– Specification compatibility
– SPR-8104

• JMS 2.0 (JSR-343)
– Long overdue, major overhaul to JMS
– Exploring a native JMS API style for use with Spring
– SPR-8197

Caching
• Support for JCache (JSR-107) compliant cache providers
– JCacheCacheManager/Cache adapters for Spring's SPI
– JCacheManager/JCacheFactoryBean

• Support for JCache's standardized caching annotations
– ideally automatically through Spring’s
<cache:annotation-driven>

• SPR-8774

Validation
• Bean Validation 1.1 (JSR-349)
– Specification compatibility
– Building on 1.0 support in Spring 3.0

• SPR-8199

Spring Core
• Migrate from CGLIB to Javassist
– For class-based proxies (AOP)
– SPR-8190

• Bean definition visibility and overriding
– Final bean definitions
– Profile-scoped beans
– @Bean methods override XML beans
– SPR-8189

Spring MVC Testing Support
• Unit tests with Mock MVC classes
– Simulates the DispatcherServlet

• Integration tests with XmlWebApplicationContext
– Configured via @ContextConfiguration and other
annotations
– Loaded via a new ContextLoader

Further Resources
• Spring Framework
– http://springframework.org
– Spring Reference Manual
– JavaDoc
• Spring Forums
– http://forum.springframework.org
• Spring JIRA
– http://jira.springframework.org

Blogs
• SpringSource Team Blog – category 3.1
– http://blog.springsource.com/category/spring/31/

• Swiftmind Blog
– http://www.swiftmind.com/blog/

Q&A

Sam Brannen

twitter: @sam_brannen
www.slideshare.net/sbrannen
www.swiftmind.com

“Spring in a Nutshell”
http://oreilly.com/catalog/9780596801946
available from O’Reilly in 2012

Spring 3.1 to 3.2 in a Nutshell - Spring I/O 2012

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