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Spring Web MVC
- 1. Spring Web MVC By: ZeeshanHanif Sr. Software Engineer Etilize Pvt. Ltd. A GfK Product data company
- 2. Agenda What isspring MVC Features Spring MVC Workflow Important Components of Spring MVC Demo – External configuration Demo – Annotation Convention over Configuration World without Rules Demo – Form Submission Demo – Session Storage Demo – REST based URL Demo – Ajax
- 3. Prerequisite Spring Core IOC & Dependency Injection
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- 5. Spring MVC TheSpring Web MVC Framework is a robust, flexible, and well-designed framework for rapidly developing web applications using the MVC design pattern.
- 6. Features Clear separationof roles. Each role — controller, validator, command object, form object, model object, handler mapping, view resolver and so on. Powerful and straightforward configuration of both framework and application classes as JavaBeans Adaptability and flexibility. Define any controller method signature you need for a given scenario
- 7. Features (cont.) Useexisting business objects as command or form objects instead of mirroring them to extend a particular framework base class Flexible model transfer. Model transfer with a name/value Map supports easy integration with any view technology A simple yet powerful JSP tag library Easier testing REST based URL support
- 8. Spring MVC Workflow Source:www.springsource.org
- 9. Important Components DispatcherServlet Controller HandlerMapping/@RequestMapping ModelAndView Model & @ModelAttribute ViewResolver
- 10. DispatcherServlet The DispatcherServlet follows the Front Controller Design Pattern for handling Client Requests. It means that whatever Url comes from the Client, this Servlet will intercept the Client Request before passing the Request Object to the Controller.
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- 12. Controller Controllers arecomponents that are being called by the Dispatcher Servlet for doing any kind of Business Logic Spring Distribution already comes with a variety of Controller Components each doing a specific purpose - spring 2.x SimpleFormController AbstractController MultiActionController Spring 3 Controller @Controller Annotation
- 13. Controller (Cont.) OldSchool of Spring MVC public class MySimpleController extends AbstractController { public ModelAndView handleRequestInternal (HttpServletRequest request, HttpServletResponse response) { return new ModelAndView("myView"); } }
- 14. Controller (Cont.) SpringMVC 3.0 @Controller public class DemoSpring3Controller { @RequestMapping("/demoSpring3") public ModelAndView helloWorld() { String msg = "Hello Spring 3 World! Etilize -- GfK"; return new ModelAndView("demosp", "message", msg); } } <context:component-scan base-package="com.gfk.etilize.controller" />
- 15. HandlerMapping A HandlerMapping provides an abstract way that tell how the Client's Url has to be mapped to the Handlers. Four concrete variation of Handler Mapping are available BeanNameUrl HandlerMapping CommonsPathMap HandlerMapping ControllerClassName HandlerMapping SimpleUrl HandlerMapping
- 16. HandlerMapping (Cont.) BeanNameUrlHandlerMapping URL request http://localhost:8080/spweb/showStudents Bean Mapping <beans> <bean id="beanNameUrl" class="org.springframework.web.servlet.handler. BeanNameUrlHandlerMapping"/> <bean name="/showStudents.jsp" class="com.gfk.etilize.ShowStudentsController"> </bean> </beans>
- 17. HandlerMapping (Cont.) SimpleUrlHandlerMapping <beanid="urlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHan dlerMapping"> <property name="urlMap"> <map> <entry key="/demoSpring.gfk"> <ref bean="demoSpringController"/> </entry> </map> </property> </bean> <bean id="demoSpringController" class="com.gfk.etilize.controller.DemoSpringController" />
- 18. HandlerMapping (Cont.) Spring3.0 uses @RequestMapping for Mapping @Controller public class DemoSpring3Controller { @RequestMapping("/demoSpring3") public ModelAndView helloWorld() { String msg = "Hello Spring 3 World"; return new ModelAndView("demosp", "message", msg); } }
- 19. ModelAndView ModelandView isreturned by the Controller object back to the Dispatcher Servlet. This class is just a Container class for holding the Model and the View information. This way of specifying a View is called a Logical View. It means that demosp either can point to something called demosp.jsp or demosp.pdf or demosp.xml ModelAndView(viewName, “Key”, object); return new ModelAndView("demosp", "message", msg);
- 20. Model & @ModelAttribute Model object Automatically created on every request @RequestMapping public void showList(Model model){ model.addAttribute("studentList", studentService.getAllStudents()); } Implicitly added to Model and can be accessed with key “student” @RequestMapping public Student showList(){ return studentService.getStudent(); }
- 21. Model & @ModelAttribute @ModelAttribute– customized name @RequestMapping public @ModelAttribute(“stu”) Student showList(){ return studentService.getStudent(); } @ModelAttribute – Form values @RequestMapping("/new") public ModelAndView getStudentForm(){ return new ModelAndView("studentForm","student",new Student()); } <form:form action="add.gfk" method="POST" commandName=" student " > Name:<form:input path="name" size="60" /><br> <input type="submit" value="Register" /></td> </form:form> @RequestMapping public void saveStudent(@ModelAttribute Student stu){ studentService.saveStudent(stu); }
- 22. View Resolver Themapping between the Logical name and the Physical View Location is taken care by the View Resolver object. Spring comes with a set of Built-In Spring Resolvers. We can write Custom View Resolvers by implementing the org.springframework.web.servlet.ViewResolver interface
- 23. View Resolver (Cont.) BeanNameViewResolver FreeMarkerViewResolver InternalResourceViewResolver JasperReportsViewResolver ResourceBundleViewResolver UrlBasedViewResolver VelocityLayoutViewResolver VelocityViewResolver XmlViewResolver XsltViewResolver
- 24. View Resolver (Cont.) InternalResourceViewResolver Controller returns - new ModelAndView("myView1") <bean id="viewResolver“ class="org.springframework.web.servlet.view.InternalResourceVie wResolver"> <property name="prefix"> <value>/WEB-INF/</value> </property> <property name="suffix"> <value>.jsp</value> </property> </bean> the prefix + the logical View Name + the suffix /WEB-INF/myView.jsp
- 25. View Resolver (Cont.) BeanNameViewResolver One of the dis-advantage of using InternalResourceViewResolver is that the name of the View file (jsp or pdf) must be present in the Web Application Context. Dynamically generated View files may not be possible. In such a case, we may use the BeanName ViewResolver which will dynamically generate View in Pdf or Excel Formats.
- 26. View Resolver (Cont.) Controllerreturns - new ModelAndView(“excel") <bean id="beanNameResolver" class="org.springframework.web.servlet.view.BeanNameViewReso lver"/> <bean id = “excel" class = "MyExcelGenerator"/>
- 27. Demo – Externalconfiguration Demo – Annotation
- 28. Convention over Configuration Write less code, get consistency Conventions available for Request mapping View name selection Model population
- 29. Convention over Configuration Mapping By RequestMapping @Controller public class DemoSpring3Controller { @RequestMapping("/demoSpring3") public void helloWorld(){} }
- 30. Convention over Configuration @Controller publicclass StudentController { @RequestMapping public void listAll(Model model){ model.addAttribute(new Student("Test",23)); } } GET /student/listAll Mapping of class and method name View with method name selected from request path Model key generated from object type
- 31. Convention over Configuration Mapping By Convention @Controller public class StudentController { URL /student/showList , View showList.jsp @RequestMapping public void showList(Model model){} URL /student/getStudent, View getStudent.jsp @RequestMapping public Student getStudent(){ … return stu; } }
- 32. World without Rules Return Type? Return Type Can be: ModelAndViewObject Model Map View String Void Any Custom or built-in datatype e.g. Student, Student[],ArrayList etc.
- 33. World without Rules(Cont.) Parameter Type? Parameter can be in any order: ServletRequest/HttpServletRequest ServletResponse/HttpServletResponse HttpSession InputStream/java.io.Reader OutputStream/java.io.Writer @RequestParam("product") int id or any type @PathVariable String name or any type @CookieValue("cookie_name") String or any type @RequestHeader("content") String or any type @ModelAttribute User us or any custom object Errors BindingResult SessionStatus
- 34. Demo – FormSubmission
- 35. @RequestParam Type Conversion @RequestMapping("/login") publicvoid login(@RequestParam String userName, @RequestParam int age){ } Optional Request parameter -- must use object for optional @RequestMapping("/login") public void login(@RequestParam(required=false) String userName){ }
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- 37. @SessionAttribute @Controller @SessionAttributes("user") public class LoginController{ @RequestMapping("/login") public User login(@RequestParam int id){ return loginService.login(id); } } User Object will be stored in session with key “user”
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- 39. @PathVariable – RESTURLs GET /students/find/5 @RequestMapping(“/find/{id}") public ModelAndView findStudent(@PathVariable int id , Model model){ model.addAttribute("stu", studentService.getStudent(id)); return new ModelAndView("searchStudent"); }
- 40. Demo – @PathVariable– REST URLs
- 41. Demo – Ajax @ResponseBody annotation instructs Spring MVC to serialize the Student to the client. Spring MVC automatically serializes to JSON because the client accepts that content type @RequestMapping(value="/student") public @ResponseBody Student getStudent( @RequestParam int id) { return studentService.getStudent(id); }
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- 43. Source Code http://www.4shared.com/zip/sHRtnXXd/De moSpringMVC.html You can find this presentation on slideshare http://www.slideshare.net/zeeshanhanif
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