Spring 3.x - Spring MVC

Spring MVCGuy Nir

January 2012

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» About Spring MVC» Architecture and design» Handler mapping» Controllers» View resolvers» Annotation driven» Summary

Agenda

Spring MVC

About Spring MVC

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» Top-level project at Spring framework Acknowledged that web is a crucial part of JEE world. Provide first-class support for web technologies• Markup generators (JSP, Velocity, Freemarker, etc …)• REST support.

» Integrates web and Spring core.

About

Spring MVC

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» Introduced with Spring 1.0 (August 2003)» Led by Rod Johnson and Juergen Hoeller» Introduced due the poor design of other frameworks

Struts Jakarta

AboutHistory

Spring MVC

Architecture and design

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Spring MVC


ServletServlet Application Context

Application Context Spring MVCSpring MVC

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» Open-close principle [1]

Open for extension, closed for modification.» Convention over configuration. [2]

» Model-View-Controller (MVC) driven. [3]

» Clear separation of concerns.

Architecture and designDesign guidelines

Spring MVC

[1] Bob Martin, The Open-Closed Principle[2] Convention over configuration[3] Model View Controller – GoF design pattern

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» Tightly coupled with HTTP Servlet API.» Request-based model.» Takes a strategy approach. [4]

» All activity surrounds the DispatcherServlet.

Architecture and designDesign guidelines - continued

Spring MVC

[4] Strategy – GoF design pattern

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Architecture and designweb.xml

Spring MVC

1 <web-app> 2 3 <servlet> 4 <servlet-name>petshop</servlet-name> 5 <servlet-class> 6 org.springframework.web.servlet.DispatcherServlet 7 </servlet-class> 8 <load-on-startup>1</load-on-startup> 9 </servlet>1011 <servlet-mapping>12 <servlet-name>petshop</servlet-name>13 <url-pattern>*.do</url-pattern>14 </servlet-mapping>15 16 </web-app>

1 <web-app> 2 3 <servlet> 4 <servlet-name>petshop</servlet-name> 5 <servlet-class> 6 org.springframework.web.servlet.DispatcherServlet 7 </servlet-class> 8 <load-on-startup>1</load-on-startup> 9 </servlet>1011 <servlet-mapping>12 <servlet-name>petshop</servlet-name>13 <url-pattern>*.do</url-pattern>14 </servlet-mapping>15 16 </web-app>

Servlet nameServlet name

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Architecture and designApplication context lookup

Spring MVC

<servlet-name><servlet-name> /WEB-INF/<servlet-name>-servlet.xml/WEB-INF/<servlet-name>-servlet.xml

petshoppetshop /WEB-INF/petshop-servlet.xml/WEB-INF/petshop-servlet.xml

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Architecture and designSpring MVC approach

Spring MVC

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Spring MVC


DispatcherServlet

DispatcherServlet

Incoming request

Outgoing response

Controller(Bean)

Controller(Bean)

Delegate

Rendered response

View renderer

View renderer

Model(JavaBean)Model

(JavaBean)

11 22

33

4 (?)4 (?)

5 (?)5 (?)66

Application context

Application context

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Spring MVC


DispatcherServlet

DispatcherServlet ControllerController

View renderer

View renderer

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Dispatcher servlet flow

Spring MVC

IncomingHTTP request

Set localeSet locale

Simple controller adapter


Annotation-based adapter


Another servlet adapter


Interceptors(postHandle)


Interceptors(preHandle)

Interceptors(preHandle) Handler adapterHandler adapter View

rendererView

renderer

LocaleView

Themes

LocaleView

ThemesSecurity

authorizationSecurity

authorization

Exception handler

Exception handler

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Spring MVC


Set localeSet locale










Interceptors(preHandle) Handler adapterHandler adapter View

rendererView

renderer

Exception handler

Exception handler

LocaleView

Themes

LocaleView

ThemesSecurity

authorizationSecurity

authorization

Controller View

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Spring MVC








Handler adapterHandler adapter Viewrenderer

Viewrenderer

Exception handler

Exception handler



public interface HandlerInterceptor {

public boolean preHandle(HttpServletRequest request,

HttpServletResponse response,

Object handler) throws Exception {

// Pre-processing callback.}

}


public boolean preHandle(HttpServletRequest request,

HttpServletResponse response,

Object handler) throws Exception {

// Pre-processing callback.}

}

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Spring MVC

IncomingHTTP request View

rendererView

renderer

Exception handler

Exception handler

Handler adapterHandler adapter







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Spring MVC








Handler adapterHandler adapter Viewrenderer

Viewrenderer

Exception handler

Exception handler


public void postHandle(HttpServletRequest request,

HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

// Post-processing callback.}

}


public void postHandle(HttpServletRequest request,

HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

// Post-processing callback.}

}



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Spring MVC









Exception handler

Exception handler

Viewrenderer

Viewrenderer

Locate current locale

Locate current locale

Render the appropriate

view

Render the appropriate

view

• ResourceBundleViewResolver• UrlBasedViewResolver• FreeMarkerViewResolver• VelocityLayoutViewResolver• JasperReportsViewResolver• InternalResourceViewResolver• XsltViewResolver• TilesViewResolver• XmlViewResolver• BeanNameViewResolver

• ResourceBundleViewResolver• UrlBasedViewResolver• FreeMarkerViewResolver• VelocityLayoutViewResolver• JasperReportsViewResolver• InternalResourceViewResolver• XsltViewResolver• TilesViewResolver• XmlViewResolver• BeanNameViewResolver

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Viewrenderer

Viewrenderer






Spring MVC









Exception handler

Exception handler

DefaultHandlerExceptionResolverDefaultHandlerExceptionResolver

Handler mapping

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» Maps between an incoming request and the appropriate controller.

Handler mapping

Spring MVC



Controller bean-name mapping

Controller class-name mapping

Static mapping

Based on annotations

[GET] http://host.com/services/userInfo.do[GET] http://host.com/services/userInfo.do

Handlers from application contextHandlers from application context

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» Dispatcher servlet: Search for all beans derived from org.springframework.web.servlet.HandlerMapping

Traverse all handlers. For each handler:• Check if handler can resolve request to a controller.• Delegate control to the controller.

Handler mapping

Spring MVC

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Handler mapping

Spring MVC

1 <?xml version="1.0" encoding="UTF-8"?> 2 3 <beans> 4 5  6 <bean class="org.springframework...ControllerClassNameHandlerMapping"/> 7 8  9 <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">10 <property name="mappings">11 <value>12 /info.do=personalInformationController13 </value>14 </property>15 </bean>16 17 <bean id="personalInformationController“18 class="com.cisco.mvc.controllers.PersonalInformationController"/>19 20 </beans>

1 <?xml version="1.0" encoding="UTF-8"?> 2 3 <beans> 4 5  6 <bean class="org.springframework...ControllerClassNameHandlerMapping"/> 7 8  9 <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">10 <property name="mappings">11 <value>12 /info.do=personalInformationController13 </value>14 </property>15 </bean>16 17 <bean id="personalInformationController“18 class="com.cisco.mvc.controllers.PersonalInformationController"/>19 20 </beans>

Controllers

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Controllers

Spring MVC

public interface Controller {

public ModelAndView handleRequest(HttpServletRequest request,HttpServletResponse response) throws Exception;

}

public interface Controller {

public ModelAndView handleRequest(HttpServletRequest request,HttpServletResponse response) throws Exception;

}

View:Object ?

View:Object ?

Model:Key/Value map

Model:Key/Value map

Model+

View

Model+

View

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Controllers

Spring MVC

1 public class LoginController implements Controller { 2 3 @Override 4 public ModelAndView handleRequest(HttpServletRequest request, 5 HttpServletResponse response) 6 throws Exception { 7 String username = request.getParameter("j_username"); 8 String password = request.getParameter("j_password"); 9 if (!validateUser(username, password)) {10 return new ModelAndView("invalidUsername.jsp", "uname", username);11 } else {12 return new ModelAndView("portal.jsp");13 }14 }1516 private boolean validateUser(String username, String password) {17 // Validate user ...18 }19 }

1 public class LoginController implements Controller { 2 3 @Override 4 public ModelAndView handleRequest(HttpServletRequest request, 5 HttpServletResponse response) 6 throws Exception { 7 String username = request.getParameter("j_username"); 8 String password = request.getParameter("j_password"); 9 if (!validateUser(username, password)) {10 return new ModelAndView("invalidUsername.jsp", "uname", username);11 } else {12 return new ModelAndView("portal.jsp");13 }14 }1516 private boolean validateUser(String username, String password) {17 // Validate user ...18 }19 }

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Controllers

Spring MVC

1 public class LoginController implements Controller { 2 3 @Override 4 public ModelAndView handleRequest(HttpServletRequest request, 5 HttpServletResponse response) 6 throws Exception { 7 String username = request.getParameter("j_username"); 8 String password = request.getParameter("j_password"); 9 if (!validateUser(username, password)) {10 int retryCount = Integer.parseInt(request.getParameter("retries"));11 Map<String, Object> model = new Map<String, Object>();12 model.put("uname", username);13 model.put(“retryCount“, retryCount + 1);1415 return new ModelAndView("invalidUsername.jsp", model);16 } else {17 return new ModelAndView("portal.jsp");18 }19 }20 }


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Controllers

Spring MVC



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Controllers

Spring MVC

<< interface >>Controller


MyControllerMyController

Handle incoming requests

Handle incoming requests

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Controllers

Spring MVC



<< abstract>>AbstractController



• supportedMethods (GET, POST, …)

• requireSession (true/false)• synchronize (true/false)• Cache control

• supportedMethods (GET, POST, …)

• requireSession (true/false)• synchronize (true/false)• Cache control

public ModelAndView handleRequest(HttpServletRequest request,HttpServletResponse

response)throws Exception { ... }

public ModelAndView handleRequest(HttpServletRequest request,HttpServletResponse


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Controllers

Spring MVC






<< abstract>>AbstractUrlViewController

<< abstract>>AbstractUrlViewController

Resolve controller based on URLResolve controller based on URL

public ModelAndView handleRequestInt(

HttpServletRequest request,HttpServletResponse


public ModelAndView handleRequestInt(

HttpServletRequest request,HttpServletResponse


View resolvers

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» Resolve a view object to actual rendered output.» Isolate application logic from underlying view

implementation. Each view is identified by a discrete object (e.g.: name). Each view is resolved to a different renderer.

View resolvers

Spring MVC

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View resolvers

Spring MVC

View resolverView resolver

XmlViewResolver

ResourceBundleViewResolver

FreeMarkerViewResolver

UrlBasedViewResolver

View: “login”View: “login”

View handlersView handlers

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View resolvers

Spring MVC

<?xml version="1.0" encoding="UTF-8"?>

<beans>

<bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver"> <property name="prefix" value="/WEB-INF/pages/" /> <property name="suffix" value=".jsp" /> </bean>

</beans>

<?xml version="1.0" encoding="UTF-8"?>

<beans>

<bean id="viewResolver" class="org.springframework.web.servlet.view.UrlBasedViewResolver"> <property name="prefix" value="/WEB-INF/pages/" /> <property name="suffix" value=".jsp" /> </bean>

</beans>

View: “login”View: “login” /WEB-INF/pages/login.jsp/WEB-INF/pages/login.jsp

Annotation driven

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» Allow us to specify all mapping and handling via annotations.

Annotation driven

Spring MVC

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Annotation drivenBasic request mapping

Spring MVC

1 @Controller 2 public class CalcController { 3 4 // [GET] http://host.com/example/calculate?first=NNN&second=MMM 5 @RequestMapping("/calculate") 6 public String calculate(HttpServletRequest request) { 7 String first = request.getParameter("first"); 8 String second = request.getParameter("second"); 9 10 int firstInt = Integer.parseInt(first);11 int secondInt = Integer.parseInt(second);12 13 return Integer.toString(firstInt + secondInt);14 }15 }

1 @Controller 2 public class CalcController { 3 4 // [GET] http://host.com/example/calculate?first=NNN&second=MMM 5 @RequestMapping("/calculate") 6 public String calculate(HttpServletRequest request) { 7 String first = request.getParameter("first"); 8 String second = request.getParameter("second"); 9 10 int firstInt = Integer.parseInt(first);11 int secondInt = Integer.parseInt(second);12 13 return Integer.toString(firstInt + secondInt);14 }15 }

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Annotation drivenSelecting method type

Spring MVC

1 @Controller 2 public class CalcController { 3 4 // [POST] http://host.com/example/calculate?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate", method = RequestMethod.POST) 6 public String calculate(HttpServletRequest request) { 7 String first = request.getParameter("first"); 8 String second = request.getParameter("second"); 9 10 int firstInt = Integer.parseInt(first);11 int secondInt = Integer.parseInt(second);12 13 return Integer.toString(firstInt + secondInt);14 }15 }

1 @Controller 2 public class CalcController { 3 4 // [POST] http://host.com/example/calculate?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate", method = RequestMethod.POST) 6 public String calculate(HttpServletRequest request) { 7 String first = request.getParameter("first"); 8 String second = request.getParameter("second"); 9 10 int firstInt = Integer.parseInt(first);11 int secondInt = Integer.parseInt(second);12 13 return Integer.toString(firstInt + secondInt);14 }15 }

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Annotation drivenAccessing request parameters

Spring MVC

1 @Controller 2 public class CalcController { 3 4 // [POST] http://host.com/example/calculate?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate", method = RequestMethod.POST) 6 public String calculate(@RequestParam("first") int first, 7 @RequestParam(“second") int second) { 8 return Integer.toString(first + second); 9 }10 }

1 @Controller 2 public class CalcController { 3 4 // [POST] http://host.com/example/calculate?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate", method = RequestMethod.POST) 6 public String calculate(@RequestParam("first") int first, 7 @RequestParam(“second") int second) { 8 return Integer.toString(first + second); 9 }10 }

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Annotation drivenMultiple handlers per controller

Spring MVC

1 @Controller 2 public class CalcController { 3 4 // [POST] http://host.com/example/calculate/add?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate/add", method = RequestMethod.POST) 6 public String calculate(@RequestParam("first") int first, 7 @RequestParam(“second") int second) { 8 return Integer.toString(first + second); 9 }

4 // [POST] http://host.com/example/calculate/sub?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate/sub", method = RequestMethod.GET) 6 public String calculate(@RequestParam("first") int first, 7 @RequestParam(“second") int second) { 8 return Integer.toString(first - second); 9 }10 }

1 @Controller 2 public class CalcController { 3 4 // [POST] http://host.com/example/calculate/add?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate/add", method = RequestMethod.POST) 6 public String calculate(@RequestParam("first") int first, 7 @RequestParam(“second") int second) { 8 return Integer.toString(first + second); 9 }

4 // [POST] http://host.com/example/calculate/sub?first=NNN&second=MMM 5 @RequestMapping(value = "/calculate/sub", method = RequestMethod.GET) 6 public String calculate(@RequestParam("first") int first, 7 @RequestParam(“second") int second) { 8 return Integer.toString(first - second); 9 }10 }

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Annotation drivenURI template

Spring MVC

1 @Controller 2 public class WeatherController { 3 4 // [GET] http://host.com/weather/972/TelAviv 5 @RequestMapping(value = "/weather/{countryCode}/{cityName}") 6 public ModelAndView getWeather(@PathVariable("countryCode") int countryCode, 7 @PathVariable("cityName") String cityName) { 8 ModelAndView mav = new ModelAndView(); 9 // Fill in model the relevant information.10 // Select a view appropriate for country.11 return mav;12 }13 }


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Annotation drivenURI template

Spring MVC



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Annotation drivenException handling

Spring MVC

1 @Controller 2 public class WeatherController { 3 4 @ExceptionHandler(IllegalArgumentException.class) 5 public String handleException(IllegalArgumentException ex, 6 HttpServletResponse response) { 7 return ex.getMessage(); 8 } 9 }

1 @Controller 2 public class WeatherController { 3 4 @ExceptionHandler(IllegalArgumentException.class) 5 public String handleException(IllegalArgumentException ex, 6 HttpServletResponse response) { 7 return ex.getMessage(); 8 } 9 }

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Annotation drivenFile upload example

Spring MVC

@Controllerpublic class FileUploadController {

@RequestMapping(value = "/uploadFile", method = RequestMethod.POST) public String handleFormUpload(@RequestParam("name") String filename, @RequestParam("file") MultipartFile file) {

if (success) { return "redirect:uploadSuccess"; } else { return "redirect:uploadFailure"; } }}


@RequestMapping(value = "/uploadFile", method = RequestMethod.POST) public String handleFormUpload(@RequestParam("name") String filename, @RequestParam("file") MultipartFile file) {

if (success) { return "redirect:uploadSuccess"; } else { return "redirect:uploadFailure"; } }}

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Annotation drivenCookies

Spring MVC


@RequestMapping(“/portal”) public String enterPortal(@CookieValue(“lastVisited“) Date lastVisited) { }

@RequestMapping(“/console”) public String enterPortal( @CookieValue(value = “lastVisited“, required = “true”) Date lastVisited) { }}


@RequestMapping(“/portal”) public String enterPortal(@CookieValue(“lastVisited“) Date lastVisited) { }

@RequestMapping(“/console”) public String enterPortal( @CookieValue(value = “lastVisited“, required = “true”) Date lastVisited) { }}

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Annotation drivenSession attributes

Spring MVC

1 @Controller 2 @SessionAttributes("userid") 3 public class PersonalInformationController { 4 5 @RequestMapping("/loginCheck") 6 public String checkUserLoggedIn(@ModelAttribute("userid") int id) { 7 // ... 8 } 9 }

1 @Controller 2 @SessionAttributes("userid") 3 public class PersonalInformationController { 4 5 @RequestMapping("/loginCheck") 6 public String checkUserLoggedIn(@ModelAttribute("userid") int id) { 7 // ... 8 } 9 }

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Annotation drivenApplication context configuration

Spring MVC

1 <?xml version="1.0" encoding="UTF-8"?> 2 3 <beans> 4 5  6 <context:annotation-config /> 7 8  9 <context:component-scan base-package="com.cisco.mvc" />10 11 12 <mvc:annotation-driven/>13 14 <mvc:interceptors>15 </mvc:interceptors>16 17 </beans>

1 <?xml version="1.0" encoding="UTF-8"?> 2 3 <beans> 4 5  6 <context:annotation-config /> 7 8  9 <context:component-scan base-package="com.cisco.mvc" />10 11 12 <mvc:annotation-driven/>13 14 <mvc:interceptors>15 </mvc:interceptors>16 17 </beans>

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Annotation drivenApplication context configuration - continued

Spring MVC

1 <?xml version="1.0" encoding="UTF-8"?> 2 3 <beans> 4 5 <mvc:interceptors> 6 <bean class="com.cisco.mvc.interceptors.SecurityInterceptor"/> 7 </mvc:interceptors> 8 9 <mvc:resources mapping="/static/**" location="/pages/"/>1011 <mvc:view-controller path="/" view-name=“homePage"/>12 13 </beans>

1 <?xml version="1.0" encoding="UTF-8"?> 2 3 <beans> 4 5 <mvc:interceptors> 6 <bean class="com.cisco.mvc.interceptors.SecurityInterceptor"/> 7 </mvc:interceptors> 8 9 <mvc:resources mapping="/static/**" location="/pages/"/>1011 <mvc:view-controller path="/" view-name=“homePage"/>12 13 </beans>

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» Spring MVC provide a clear separation between a model, view and controller

» Provide both XML-based and annotation-based approaches.

» Enriched by Spring application context.» Provide a broad range of pre-configured facilities.» Takes convention over configuration approach.» Uses open-close principle.

Summary

Spring MVC

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» Spring MVC reference guide: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/mvc.html

SummaryReferences

Spring MVC

Q & A

Technology

Spring 3.x - Spring MVC