Request URL is a URL that the user will use to access our web application. In this tutorial, we will learn how to define a request URL for a controller in Spring MVC.
Define the request URL
A controller can handle one or more requests with different request URLs. Spring MVC gives us the @RequestMapping annotation to define a request URL.
In the example of the previous tutorial, you see that the HomeController has defined a request URL:
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@RequestMapping(value = "/", method = RequestMethod.GET) |
Controller with 1 request URL
If the @RequestMapping annotation with the request URL is defined only above the definition of a class, then this controller handles only one request.
For example:
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package com.huongdanjava.springmvc; import java.text.DateFormat; import java.util.Date; import java.util.Locale; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; /** * Handles requests for the application home page. */ @Controller @RequestMapping(value = "/", method = RequestMethod.GET) public class HomeController { private static final Logger logger = LoggerFactory.getLogger(HomeController.class); /** * Simply selects the home view to render by returning its name. */ @RequestMapping public String home(Locale locale, Model model) { logger.info("Welcome home! The client locale is {}.", locale); Date date = new Date(); DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale); String formattedDate = dateFormat.format(date); model.addAttribute("serverTime", formattedDate ); return "home"; } } |
In this case, if we add another method with the @RequestMapping annotation without the request URL:
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package com.huongdanjava.springmvc; import java.text.DateFormat; import java.util.Date; import java.util.Locale; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; /** * Handles requests for the application home page. */ @Controller @RequestMapping(value = "/", method = RequestMethod.GET) public class HomeController { private static final Logger logger = LoggerFactory.getLogger(HomeController.class); /** * Simply selects the home view to render by returning its name. */ @RequestMapping public String home(Locale locale, Model model) { logger.info("Welcome home! The client locale is {}.", locale); Date date = new Date(); DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale); String formattedDate = dateFormat.format(date); model.addAttribute("serverTime", formattedDate); return "home"; } @RequestMapping public String login() { return "login"; } } |
then when we run, we get an error immediately:
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Caused by: java.lang.IllegalStateException: Ambiguous mapping found. Cannot map 'homeController' bean method public java.lang.String com.huongdanjava.springmvc.HomeController.home(java.util.Locale,org.springframework.ui.Model) to {[/],methods=[GET],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already 'homeController' bean method public java.lang.String com.huongdanjava.springmvc.HomeController.login() mapped. at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:183) at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:147) at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:109) at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initApplicationContext(AbstractHandlerMethodMapping.java:89) at org.springframework.context.support.ApplicationObjectSupport.initApplicationContext(ApplicationObjectSupport.java:119) at org.springframework.web.context.support.WebApplicationObjectSupport.initApplicationContext(WebApplicationObjectSupport.java:72) at org.springframework.context.support.ApplicationObjectSupport.setApplicationContext(ApplicationObjectSupport.java:73) at org.springframework.context.support.ApplicationContextAwareProcessor.invokeAwareInterfaces(ApplicationContextAwareProcessor.java:117) at org.springframework.context.support.ApplicationContextAwareProcessor.postProcessBeforeInitialization(ApplicationContextAwareProcessor.java:92) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:394) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1448) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519) ... 66 more |
Controller with multiple request URLs
If the @RequestMapping annotation with the request URL is defined in the methods, the controller can handle many different requests.
The following example of the HomeController class can handle two requests that come from the user including the home page and the login page:
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package com.huongdanjava.springmvc; import java.text.DateFormat; import java.util.Date; import java.util.Locale; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; /** * Handles requests for the application home page. */ @Controller public class HomeController { private static final Logger logger = LoggerFactory.getLogger(HomeController.class); /** * Simply selects the home view to render by returning its name. */ @RequestMapping(value = "/", method = RequestMethod.GET) public String home(Locale locale, Model model) { logger.info("Welcome home! The client locale is {}.", locale); Date date = new Date(); DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale); String formattedDate = dateFormat.format(date); model.addAttribute("serverTime", formattedDate); return "home"; } @RequestMapping(value = "/login") public String login() { return "login"; } } |
You can also define a method that handles many requests by defining the request URL as follows:
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package com.huongdanjava.springmvc; import java.text.DateFormat; import java.util.Date; import java.util.Locale; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; /** * Handles requests for the application home page. */ @Controller public class HomeController { private static final Logger logger = LoggerFactory.getLogger(HomeController.class); /** * Simply selects the home view to render by returning its name. */ @RequestMapping(value = { "/home", "/login", "/logout" }, method = RequestMethod.GET) public String home(Locale locale, Model model) { logger.info("Welcome home! The client locale is {}.", locale); Date date = new Date(); DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale); String formattedDate = dateFormat.format(date); model.addAttribute("serverTime", formattedDate); return "home"; } } |
Concatenate request URL
In case where both class and method are declared with the @RequestMapping annotation along with the request URL, then the request URL which used by the user to access a given page must be the request URL of the class plus the method’s request URL.
I have the following example:
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package com.huongdanjava.springmvc; import java.text.DateFormat; import java.util.Date; import java.util.Locale; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; /** * Handles requests for the application home page. */ @Controller @RequestMapping("test") public class HomeController { private static final Logger logger = LoggerFactory.getLogger(HomeController.class); /** * Simply selects the home view to render by returning its name. */ @RequestMapping(value = "home", method = RequestMethod.GET) public String home(Locale locale, Model model) { logger.info("Welcome home! The client locale is {}.", locale); Date date = new Date(); DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale); String formattedDate = dateFormat.format(date); model.addAttribute("serverTime", formattedDate); return "home"; } } |
In the above example, I have declared the @RequestMapping annotation both on the class (“test”) and method (“home”), the URL request that the user needs to access the home page must be “/test/home”. ”
Result:
