@Controller marked class cannot implements Comparator [SPR-5935]

[spring-projects-issues]

Robert Kristofic opened SPR-5935 and commented

If you have @Controller marked class which implements Comparator.

Exception:

javax.servlet.ServletException: No adapter for handler
[plaut.jfos.module.dashboard.web.controller.PartnerDetailController@2f1f479a]:
Does your handler implement a supported interface like Controller?
org.springframework.web.servlet.DispatcherServlet.getHandlerAdapter
(DispatcherServlet.java:1091)
org.springframework.web.servlet.DispatcherServlet.doDispatch
(DispatcherServlet.java:874)
org.springframework.web.servlet.DispatcherServlet.doService
(DispatcherServlet.java:809)
org.springframework.web.servlet.FrameworkServlet.processRequest
(FrameworkServlet.java:571)
org.springframework.web.servlet.FrameworkServlet.doPost
(FrameworkServlet.java:511)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal
(CharacterEncodingFilter.java:96)
org.springframework.web.filter.OncePerRequestFilter.doFilter
(OncePerRequestFilter.java:76)
org.springframework.security.util.FilterChainProxy
$VirtualFilterChain.doFilter(FilterChainProxy.java:359)
org.springframework.security.ui.logout.LogoutFilter.doFilterHttp
(LogoutFilter.java:89)
org.springframework.security.ui.SpringSecurityFilter.doFilter
(SpringSecurityFilter.java:53)
org.springframework.security.util.FilterChainProxy
$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
org.springframework.security.ui.AbstractProcessingFilter.doFilterHttp
(AbstractProcessingFilter.java:271)
org.springframework.security.ui.SpringSecurityFilter.doFilter
(SpringSecurityFilter.java:53)
org.springframework.security.util.FilterChainProxy
$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
org.springframework.security.ui.x509.X509ProcessingFilter.doFilter
(X509ProcessingFilter.java:137)
org.springframework.security.util.FilterChainProxy
$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
plaut.jfos.framework.server.JfosContextOUSetterFilter.doFilter
(JfosContextOUSetterFilter.java:59)
org.springframework.security.util.FilterChainProxy
$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp
(HttpSessionContextIntegrationFilter.java:235)
org.springframework.security.ui.SpringSecurityFilter.doFilter
(SpringSecurityFilter.java:53)
org.springframework.security.util.FilterChainProxy
$VirtualFilterChain.doFilter(FilterChainProxy.java:371)
org.springframework.security.util.FilterChainProxy.doFilter
(FilterChainProxy.java:174)
org.springframework.security.util.FilterToBeanProxy.doFilter
(FilterToBeanProxy.java:99)

Controller code (not complete):

@Controller
public class PartnerDetailController extends AbstractDashboardController implements Comparator<OrganizationUnit> {

//....

@RequestMapping(value = "/dashboard/partnerdetail.do")
public String process(@ModelAttribute("formData") PartnerDetailForm formData, HttpSession session) {

    formData.setOrganizationUnits(Collections.sort(codeListService.getOrganizationUnits(), this));

    return "/dashboard/partnerdetail.jsp";
}

// ....

@Override
public int compare(OrganizationUnit o1, OrganizationUnit o2) {
    if(o1 == null || o1.getLabel() == null) {
        return -1;
    }
    else if(o2 == null || o2.getLabel() == null) {
        return 1;
    }
    else return o1.getLabel().compareTo(o2.getLabel());
}

}

If you remove Comparator interface and compare, everything is OK.

---

Affects: 2.5.5

Issue Links:

• MVC Annotation Inheritance [SPR-6093] #10761 MVC Annotation Inheritance

[spring-projects-issues]

Juergen Hoeller commented

This looks like a side effect of proxying: You are probably proxying your controller using AOP, which by default chooses to proxy interfaces only if interfaces are being declared; otherwise it chooses a CGLIB class proxy. So implementing the Comparator interface might surprisingly switch from class proxy to interface proxy here.

Make sure to specify proxy-target-class="true" when proxying annotated controllers. And make sure to use 3.0 RC1 or later in order for proxied controllers to work reliably.

Juergen