Extending Spring for Custom Usage

  • 3,332 views
Uploaded on

The Spring framework packs a lot of punch, out of the box! The surface-level component model's extraordinarily flexible, and works well with in most situations, but the real power of Spring lays just …

The Spring framework packs a lot of punch, out of the box! The surface-level component model's extraordinarily flexible, and works well with in most situations, but the real power of Spring lays just underneath, in the numerous SPIs that Spring exposes, so that you can tailor the component model to your own use cases. Spring's SPI's are a great example of what Bob Martin describes as the open-closed principle, and it provides the solid underpinnings upon which the other Spring frameworks, including Spring Integration, Spring MVC and Spring Batch are built. In this talk, Josh Long, the Spring developer advocate from SpringSource, provides a walking tour of Spring's extension points.

More in: Technology , Education
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
No Downloads

Views

Total Views
3,332
On Slideshare
0
From Embeds
0
Number of Embeds
1

Actions

Shares
Downloads
38
Comments
0
Likes
3

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Tailoring Spring for Custom Usage • Josh Long, SpringSource, a division of VMware 1Sunday, February 19, 12
  • 2. About Josh Long (Spring Developer Advocate) @starbuxman josh.long@springsource.com th s i is im po rta nt ! 2Sunday, February 19, 12
  • 3. Agenda Explore the value of a framework Exploit some of the lesser known, but powerful, extension hooks in the core Spring framework QA 3Sunday, February 19, 12
  • 4. Spring’s aim: bring simplicity to java development data web tier integration batch access & service tier & mobile processing / NoSQL / RIA messaging Big Data The Spring framework the cloud: lightweight traditional CloudFoundry WebSphere tc Server VMForce JBoss AS Tomcat Google App Engine WebLogic Jetty Amazon Web Services (on legacy versions, too!) 4Sunday, February 19, 12
  • 5. The Spring ApplicationContext • Spring Manages the beans you tell it to manage – use annotations (JSR 250, JSR 330, native) – XML – Java configuration – component scanning • You can of course use all of them! Mix ‘n match • All configuration styles tell the ApplicationContext how to manage your beans 5Sunday, February 19, 12
  • 6. Spring, a walking tour • Demos: – introduce the tool chain – how to “setup” Spring – basic dependency injection • annotations (JSR 250, JSR 330, native) • xml • java configuration 6Sunday, February 19, 12
  • 7. Spring Integration rules!! Not confidential. Tell everyone. 7Sunday, February 19, 12
  • 8. ...but??!? ...what if it doesn’t do what I want? 8Sunday, February 19, 12
  • 9. What is Spring Integration?FLEXIBLE v Not confidential. Tell everyone. 9Sunday, February 19, 12
  • 10. 10Sunday, February 19, 12
  • 11. do NOT reinvent the Wheel! 11Sunday, February 19, 12
  • 12. The Open/Closed Principle "software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification” -Bob Martin 12Sunday, February 19, 12
  • 13. Working with Lots of Beans • One way to selectively augment beans at the lower level: – BeanPostProcessor • are regular beans and are run after the configured beans have been created, but before the context is finished setting up – BeanFactoryPostProcessor • is run before any of the beans definitions are realized • comes before BPP • A more natural alternative is Spring’s AOP support – built on top of AspectJ – provides a very convenient, powerful way to solve cross cutting problems 13Sunday, February 19, 12
  • 14. Spring, a walking tour • Demos: – Bean*PostProcessor – AspectJ 14Sunday, February 19, 12
  • 15. Life Cycles • Life Cycles for different folks – “safe and consistent” - use the interfaces • InitializingBean, DisposableBean • correspond to init-method and destroy-method attributes – Simple and component-centric : use the annotations • @PostConstruct, @PreDestroy • correspond to init-method and destroy-method attributes – More power: SmartLifecycle • gives you the ability to dynamically start and stop beans in a certain order as well as to query whether the bean’s been started or not. 15Sunday, February 19, 12
  • 16. Scopes • Spring beans have scopes – default: singleton – can be: • prototype • HTTP session • HTTP request • HTTP application (servlet, basically) • “step” in Spring batch • thread-local • Spring Web Flow “flow” scoped • Spring Web Flow “conversation scoped” • Spring Web Flow “view” scoped (in JSF) • Activiti BPMN2 process-scoped 16Sunday, February 19, 12
  • 17. Scopes – Implement o.s.beans.factory.config.Scope – register the scope with a o.s.beans.factory.config.CustomScopeConfigurer public interface Scope { Object get(String name, ObjectFactory<?> objectFactory); Object remove(String name); void registerDestructionCallback(String name, Runnable callback); Object resolveContextualObject(String key); String getConversationId(); } 17Sunday, February 19, 12
  • 18. Scopes – Implement o.s.beans.factory.config.Scope – register the scope with a o.s.beans.factory.config.CustomScopeConfigurer public interface Scope { Object get(String name, ObjectFactory<?> objectFactory); map-like lookup of beans in a Object remove(String name); given scope void registerDestructionCallback(String name, Runnable callback); Object resolveContextualObject(String key); String getConversationId(); } 17Sunday, February 19, 12
  • 19. Scopes – Implement o.s.beans.factory.config.Scope – register the scope with a o.s.beans.factory.config.CustomScopeConfigurer public interface Scope { Object get(String name, ObjectFactory<?> objectFactory); map-like lookup of beans in a Object remove(String name); given scope void registerDestructionCallback(String name, Runnable callback); Object resolveContextualObject(String key); well known beans like the HttpServletRequest ‘request’ for String getConversationId(); ‘request’ scope } 17Sunday, February 19, 12
  • 20. Scopes – Implement o.s.beans.factory.config.Scope – register the scope with a o.s.beans.factory.config.CustomScopeConfigurer public interface Scope { Object get(String name, ObjectFactory<?> objectFactory); map-like lookup of beans in a Object remove(String name); given scope void registerDestructionCallback(String name, Runnable callback); Object resolveContextualObject(String key); well known beans like the HttpServletRequest ‘request’ for String getConversationId(); ‘request’ scope } null, or storage specific ‘conversation’ ID 17Sunday, February 19, 12
  • 21. Spring, a walking tour • Demos: – life cycle callbacks – scopes • using • creating your own 18Sunday, February 19, 12
  • 22. Getting Beans from Strange Places • FactoryBeans • Spring Expression Language – convenient way to get at values and inject them • Spring environment specific beans (profiles) – introduced in Spring 3.1 – make it easy to conditionally define an object based on some sort of runtime condition 19Sunday, February 19, 12
  • 23. Getting Beans from Strange Places • FactoryBeans – interface that’s used to provide a reusable definition of how to create a complicated object with many dependencies – Related: Java configuration, and builders • prefer both over FactoryBeans where possible 20Sunday, February 19, 12
  • 24. Getting Beans from Strange Places • Spring Expression Language – convenient way to get at values and inject them – Andy Clement’s a genius – like the Unified JSF EL, on steroids – Can be used in Java, XML • @Value(“#{ ... }”) or value = “#{ .. }” 21Sunday, February 19, 12
  • 25. Getting Beans from Strange Places • Spring profiles • @Profile(“production”) @Configuration ... • <beans profile = ‘production’> ... </beans> – Use System properties or simply specify the active profile on the environment – Use ApplicationContextInitializer in web applications 22Sunday, February 19, 12
  • 26. Getting Beans from Strange Places • An ApplicationContextInitializer public interface ApplicationContextInitializer <C extends ConfigurableApplicationContext> { void initialize(C applicationContext); } 23Sunday, February 19, 12
  • 27. Getting Beans from Strange Places • Demos: – FactoryBeans – SpEL – Profiles • ApplicationContextInitializers 24Sunday, February 19, 12
  • 28. Using Spring’s Resources • Spring supports out of the box ClassPathResource, FileResource system, etc. • Writing your own Resource implementations public interface Resource extends InputStreamSource { boolean exists(); boolean isReadable(); boolean isOpen(); URL getURL() throws IOException; URI getURI() throws IOException; File getFile() throws IOException; long contentLength() throws IOException; long lastModified() throws IOException; Resource createRelative(String relativePath) throws IOException; String getFilename(); String getDescription(); } 25Sunday, February 19, 12
  • 29. Object to XML Marshallers • Easy to add your own Marshaller (and Unmarshaller) public interface Marshaller { boolean supports(Class<?> clazz); void marshal(Object graph, Result result) throws IOException, XmlMappingException; } 26Sunday, February 19, 12
  • 30. Object to XML Marshallers • Demos: – a custom object-to-XML marshaller 27Sunday, February 19, 12
  • 31. REST • Spring MVC for the server @RequestMapping( value = “/crm/customers/{id}” , method =HttpMethod.GET) public @ResponseBody Customer lookupCustomerById( @PathVariable(“id”) long customerId ) { ... return customer; } 28Sunday, February 19, 12
  • 32. REST • RestTemplate for the client (Android, SE, web applications, etc.) RestTemplate rt = new RestTemplate() ; String url = “http://mysvc.cloudfoundry.com/crm/customer/{id}”; Customer customer = rt.getForObject( url, Customer.class, 22); 29Sunday, February 19, 12
  • 33. REST • Both need o.s.http.converter.HttpMessageConverters • Spring supports: – object-to-XML (JAXB as well as any Spring OXM impl) – object-to-JSON – binary data (o.s.resource.Resource references or byte[]) – ATOM/RSS – images • Easy to add your own 30Sunday, February 19, 12
  • 34. Registering a custom HttpMessageConverter @EnableWebMvc public class WebConfiguration extends WebMvcConfigurerAdapter { @Override public void configureMessageConverters( List<HttpMessageConverter<?>> converters) { } } 31Sunday, February 19, 12
  • 35. REST • Demos: – Writing and using a customer HttpMessageConverter 32Sunday, February 19, 12
  • 36. Transactions • Spring supports declarative transaction management – @EnableTransactionManagement or <tx:annotation-driven/> • PlatformTransactionManager implementations used to manage transactions – lots of options out of the box: • AMQP, JMS, JTA, JDBC, JDO, JPA, WebLogic-specific, WebSphere-specific, OC4J-specific, etc. 33Sunday, February 19, 12
  • 37. Transactions • PlatformTransactionManager abstracts the notion of a transactional “unit of work.” public interface PlatformTransactionManager { TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException; void commit(TransactionStatus status) throws TransactionException; void rollback(TransactionStatus status) throws TransactionException; } 34Sunday, February 19, 12
  • 38. Caching • CacheManager’s maintain Caches. – CacheManagers are like ‘connections’ – Caches are like regions of a cache public interface CacheManager { public interface Cache { Cache getCache(String name); Collection<String> getCacheNames(); interface ValueWrapper { } Object get(); } String getName(); Object getNativeCache(); ValueWrapper get(Object key); void put(Object key, Object value); void evict(Object key); void clear(); } 35Sunday, February 19, 12
  • 39. Writing a custom View and View Resolver 36Sunday, February 19, 12
  • 40. Writing a custom View and View Resolver • Easy to add your own View – supported views out of the box: FreeMarker, Velocity, Excel, PDFs, JasperReports, XSLT, Jackson, JSTL, etc. – Lots of contributions from the open source community: • Thymeleaf http://www.thymeleaf.org/ • Mustache by Sean Scanlon https://github.com/sps/mustache-spring-view 37Sunday, February 19, 12
  • 41. Writing a custom View and View Resolver public interface ViewResolver { View resolveViewName(String viewName, Locale locale) throws Exception; } 38Sunday, February 19, 12
  • 42. Writing a custom View and View Resolverpublic interface View { String RESPONSE_STATUS_ATTRIBUTE = View.class.getName() + ".responseStatus"; String getContentType(); void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response) throws Exception;} 39Sunday, February 19, 12
  • 43. Writing a custom View and View Resolver @Bean public ViewResolver myCustomViewResolver(){ ... } if ‘detectAllViewResolvers’ is true, all ViewResolvers types will be registered. @Bean public MyCustomViewResolver viewResolver() { ... } 40Sunday, February 19, 12
  • 44. Writing a custom View and View Resolver @Bean public ViewResolver myCustomViewResolver(){ ... } if ‘detectAllViewResolvers’ is true, all ViewResolvers types will be registered. @Bean public MyCustomViewResolver viewResolver() { ... if ‘detectAllViewResolvers’ is false, it’ll lookup a bean by a } well known name 40Sunday, February 19, 12
  • 45. Writing a custom View and View Resolver • Demo: writing a custom view/view resolver 41Sunday, February 19, 12
  • 46. Writing Adapters in Spring Integration 42Sunday, February 19, 12
  • 47. Writing Adapters in Spring Integration • MessageSource for inbound adapters • MessageHandler for outbound adapters MessageSource MessageHandler 43Sunday, February 19, 12
  • 48. Writing Adapters in Spring Integration • Inbound channel adapter “receives” message from external system inward relative to Spring Integration code package org.springframework.integration.core; public interface MessageSource<T> { org.springframework.integration.Message<T> receive(); } <int:channel id = “in” /> <int:inbound-channel-adapter channel = “in” ref = “myCustomMessageSource” > <int:cron-trigger ... /> </int:inbound-channel-adapter> 44Sunday, February 19, 12
  • 49. Writing Adapters in Spring Integration • Outbound channel adapter “publishes” message from Spring Integration outward relative to Spring Integration code package org.springframework.integration.core; public interface MessageHandler { void handleMessage( org.springframework.integration.Message<?> message) throws org.springframework.integration.MessagingException; } <int:channel id = “out” /> <int:outbound-channel-adapter channel = “out” ref = “myCustomMessageHandler” /> 45Sunday, February 19, 12
  • 50. Spring Integration File System Adapters • Spring Integration provides rich file system adapters – FTP, SFTP, FTPS, files in general – But... what about SMB/CIFS? 46Sunday, February 19, 12
  • 51. Writing Readers and Writers in Spring Batch • ItemReader for inbound adapters • ItemWriters for outbound adapters 47Sunday, February 19, 12
  • 52. Summary / Questions • code: git.springsource.org:spring-samples/spring- samples.git • blog.springsource.org • josh.long@springsource.com • springsource.com/developer/sts 48Sunday, February 19, 12
  • 53. Q&A 49 © 2011 SpringOne 2GX 2011. All rights reserved. Do not distribute without permission.Sunday, February 19, 12