Ambiguous mapping found with ControllerClassNameHandlerMapping - spring

Question

How to map requests to methods without explicit annotations on top of methods? For instance, the following request:
http://somedomain:8080/SampleSpring/access/loginFailed
should be mapped to
"loginFailed" method of "AccessController" without the need of explicit annotation on method like:
#RequestMapping("/access/loginFailed")
Here is my spring configuration:
<context:component-scan base-package="com.robikcodes.samplespring"/>
<mvc:annotation-driven/>
<bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping">
<property name="basePackage" value="com.robikcodes.samplespring.controller"/>
<property name="caseSensitive" value="true"/>
<property name="defaultHandler">
<bean class="org.springframework.web.servlet.mvc.UrlFilenameViewController"/>
</property>
</bean>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"/>
</bean>
Here is my controller:
#Controller
public class AccessController{
#RequestMapping(method = RequestMethod.GET)
public void login(ModelMap m) {}
#RequestMapping(method = RequestMethod.GET)
public String loginFailed(ModelMap m) {
m.addAttribute("error", "true");
return "access/login";
}
#RequestMapping(method = RequestMethod.GET)
public String logout(ModelMap m) {
m.addAttribute("logoutStatus","true");
return "access/login";
}
}
I got the following error (seems like only login method was mapped properly):
org.apache.catalina.LifecycleException: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping found. Cannot map 'accessController' bean method
public java.lang.String com.robikcodes.samplespring.controller.AccessController.logout(org.springframework.ui.ModelMap)
to {[],methods=[GET],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already 'accessController' bean method
public void com.robikcodes.samplespring.controller.AccessController.login(org.springframework.ui.ModelMap) mapped.

Answer 1

You're using ControllerClassNameHandlerMapping with an assumption that is not correct; from Java doc:
Implementation of HandlerMapping that follows a simple convention for
generating URL path mappings from the class names of registered
Controller beans as well as #Controller annotated beans.
The documentation does not say that it also follows method names. The main reference of comparing "handler mappings" for your controller is the #RequestMapping annotations put on your methods. So, with your controller Spring reads them as:
{methods=[GET],params=[],headers=[],consumes=[],produces=[],custom=[]}
for all the defined methods in AccessController that has the following #RequestMapping:
#RequestMapping(method = RequestMethod.GET)
That's why you see the ambiguous exception.
To my understanding, the cleanest solution is to use value attribute of #RequestMapping to define different request URIs. It's not really recommended to go for a solution that tries to map request URIs to method names.