How implement the interface FlowExecutionExceptionHandler

问题

I'm trying to customize my application to handle an exception throwed by webflow, the exception is SpelEvaluationException an especialization of EvaluationException. According with the documentation I implemented the interface FlowExecutionExceptionHandler and stayed like below:

@Named
public class PerfilExceptionHandler implements FlowExecutionExceptionHandler {

private static final Logger LOGGER = LoggerFactory.getLogger(PerfilExceptionHandler.class);

@Override
public boolean canHandle(final FlowExecutionException exception) {
    return exception.getCause() instanceof EvaluationException;
}

@Override
public void handle(final FlowExecutionException exception, final RequestControlContext context) {

    LOGGER.info("handling exception {}", exception.getMessage());

    TransitionExecutingFlowExecutionExceptionHandler handler = new TransitionExecutingFlowExecutionExceptionHandler();

    handler.add(CustomException.class, "error");
}

}

Then I have been received a NullPoinerException, follows the stacktrace:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:894)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
br.com.company.portal.web.filter.NegarAcessoSemPerfilAtivoFilter.doFilterInternal(NegarAcessoSemPerfilAtivoFilter.java:49)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:65)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:144)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
org.springframework.security.config.debug.DebugFilter.invokeWithWrappedRequest(DebugFilter.java:69)
org.springframework.security.config.debug.DebugFilter.doFilter(DebugFilter.java:58)
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96

If someone can help me, I'm apreciated

Edit 1

Prasad

Follows the code:

<view-state id="perfil" view="/perfil/add">
    <on-entry>
        <set name="flowScope.urlRedirect" value="requestParameters.url"/>
        <set name="flowScope.mapSistemaPerfis" value="perfilServiceImpl.buscarSistemasComPefis(requestParameters.identificador, requestParameters.idProduto)" />
    </on-entry>

    <transition on="submit" to="savePerfil" />
    <exception-handler bean="perfilExceptionHandler"/>
</view-state>

The error occurs when an user doesn't pass the request parameters required to call method buscarSistemasComPerfis

Tks in advance

回答1:

Instead of implementing FlowExecutionExceptionHandler, try extending TransitionExecutingFlowExecutionExceptionHandler like below:

public class PerfilExceptionHandler extends
        TransitionExecutingFlowExecutionExceptionHandler {

Also, you have given

handler.add(CustomException.class, "error");

Have you defined target state id "error" in your webflow definition?
Using add() inside TransitionExecutingFlowExecutionExceptionHandler.exposeException() method definition would be useful for identifying target state id for a particular exception.

回答2:

Ivan,

Since requestparameters is not present, when spel parser get the expression, it will see like:

     perfilServiceImpl.buscarSistemasComPefis(,);

and so you get SpelEvaluationException. The work around to handle this type of scenario is:

<view-state id="perfil" view="/perfil/add">
<on-entry>
    <set name="flowScope.urlRedirect" value="requestParameters.url"/>
    <set name="requestScope.identificador" value="requestParameters.identificador" type="string"/>
    <set name="requestScope.idProduto" value="requestParameters.idProduto" type="string"/>
    <set name="flowScope.mapSistemaPerfis" value="perfilServiceImpl.buscarSistemasComPefis(requestScope.identificador, requestScope.idProduto)" />
</on-entry>

<transition on="submit" to="savePerfil" />
<exception-handler bean="perfilExceptionHandler"/>

This way even if requestParameters is not passed, your method receives the parameters as null values, which you can handle accordingly.

来源：https://stackoverflow.com/questions/22506859/how-implement-the-interface-flowexecutionexceptionhandler

标签

Spring

spring-webflow