Building RESTful applications using Spring MVC
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The document discusses the implementation of RESTful applications using Spring MVC, detailing REST concepts, architecture design, and practical coding examples. It explains key REST principles such as identifiable resources, uniform interfaces, stateless conversations, and hypermedia support, providing code samples for creating a REST API with Spring MVC. Additionally, it highlights the use of Spring features to handle RESTful services, including annotations for request mapping and response handling.
Building RESTful applications using Spring MVC
- 1. Restful applications using Spring MVC Kamal Govindraj TenXperts Technologies
- 2. About Me Programming for 13 Years Architect @ TenXperts Technologies Trainer / Consultant @ SpringPeople Technologies Enteprise applications leveraging open source frameworks (spring,hibernate, gwt,jbpm..) Key contributor to InfraRED & Grails jBPM plugin (open source)
- 3. Agenda What is REST? REST Concepts RESTful Architecture Design Spring @MVC Implement REST api using Spring @MVC 3.0
- 4. What is REST? Representational State Transfer Term coined up by Roy Fielding − Author of HTTP spec Architectural style Architectural basis for HTTP − Defined a posteriori
- 5. Core REST Concepts Identifiable Resources Uniform interface Stateless conversation Resource representations Hypermedia
- 6. Identifiable Resources Everything is a resource − Customer − Order − Catalog Item Resources are accessed by URIs
- 7. Uniform interface Interact with Resource using single, fixed interface GET /orders - fetch list of orders GET /orders/1 - fetch order with id 1 POST /orders – create new order PUT /orders/1 – update order with id 1 DELETE /orders/1 – delete order with id 1 GET /customers/1/order – all orders for customer with id 1
- 8. Resource representations More that one representation possible − text/html, image/gif, application/pdf Desired representation set in Accept HTTP header − Or file extension Delivered representation show in Content- Type Access resources through representation Prefer well-known media types
- 9. Stateless conversation Server does not maintain state − Don’t use the Session! Client maintains state through links Very scalable Enforces loose coupling (no shared session knowledge)
- 10. Hypermedia Resources contain links Client state transitions are made through these links Links are provided by server Example <oder ref=”/order/1”> <customer ref=”/customers/1”/> <lineItems> <lineItem item=”/catalog/item/125” qty=”10”/> <lineItem item=”/catalog/item/150” qty=”5”> </lineItems> </oder>
- 12. RESTful application design Identify resources − Design URIs Select representations − Or create new ones Identify method semantics Select response codes
- 13. Implement Restful API using Spring MVC
- 14. Spring @MVC @Controller public class AccountController { @Autowired AccountService accountService; @RequestMapping("/details") public String details(@RequestParam("id")Long id, Model model) { Account account = accountService.findAccount(id); model.addAttribute(account); return "account/details"; } } account/details.jsp <h1>Account Details</h1> <p>Name : ${account.name}</p> <p>Balance : ${account.balance}</p> ../details?id=1
- 15. RESTful support in Spring 3.0 Extends Spring @MVC to handle URL templates - @PathVariable Leverages Spring OXM module to provide marshalling / unmarshalling (castor, xstream, jaxb etc) @RequestBody – extract request body to method parameter @ResponseBody – render return value to response body using converter – no views required
- 16. REST controller @Controller public class AccountController { @RequestMapping(value="/accounts",method=RequestMethod.GET) @ResponseBody public AccountList getAllAcccount() { } @RequestMapping(value="/accounts/${id}",method=RequestMethod.GET) @ResponseBody public Account getAcccount(@PathVariable("id")Long id) { } @RequestMapping(value="/accounts/",method=RequestMethod.POST) @ResponseBody public Long createAcccount(@RequestBody Account account) { } @RequestMapping(value="/accounts/${id}",method=RequestMethod.PUT) @ResponseBody public Account updateAcccount(@PathVariable("id")Long id, @RequestBody Account account) { } @RequestMapping(value="/accounts/${id}",method=RequestMethod.DELETE) @ResponseBody public void deleteAcccount(@PathVariable("id")Long id) { } }
- 17. web.xml <servlet> <servlet-name>rest-api</servlet-name> <servlet-class>org....web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>rest-api</servlet-name> <url-pattern>/rest/*</url-pattern> </servlet-mapping>
- 18. rest-api-servlet-context.xml <bean id="marshaller" class="...oxm.xstream.XStreamMarshaller"> <property name="aliases"> <map> <entry key="category" value="...domain.Category"/> <entry key="catalogItem" value="...domain.CatalogItem"/> </map> </property> </bean>
- 19. rest-api-servlet-context.xml <bean class="...mvc.annotation.AnnotationMethodHandlerAdapter"> <property name="messageConverters"> <util:list> <bean class="...http.converter.xml.MarshallingHttpMessageConverter"> <constructor-arg ref="marshaller" /> </bean> <bean class="...http.converter.StringHttpMessageConverter" /> </util:list> </property> </bean>
- 20. Invoke REST services The new RestTemplate class provides client- side invocation of a RESTful web-service HTTP RestTemplate Method Method DELETE delete(String url, String... urlVariables) GET getForObject(String url, Class<t> responseType, String … urlVariables) HEAD headForHeaders(String url, String… urlVariables) OPTIONS optionsForAllow(String url, String… urlVariables) POST postForLocation(String url, Object request, String… urlVariables) PUT put(String url, Object request, String…urlVariables)
- 21. REST template example AccountList accounts = restTemplate.getForObject("/accounts/",AccountList.class); Account account = restTemplate.getForObject("/accounts/${id}",Account.class ,"1"); restTemplate.postForLocation("/accounts/", account); restTemplate.put("/accounts/${id}",account,"1"); restTemplate.delete("/accounts/${id}", "1");
- 22. Demo
- 23. Questions?
- 24. Thank You