Spring Integration - ErrorMessageExceptionTypeRouter NullPointerException - how to fix it?

Question

I made a simple test and it dosen't work.

@RunWith(SpringRunner.class)
@SpringBootTest
@ContextConfiguration(classes = {SIConfiguration.class, ExceptionTypeRouter.class})
public class ExceptionTypeRouterTest {

    @Autowired
    @Qualifier("inDefaultChannel")
    private DirectChannel in;

    @Test
    public void fistRouteTest() {

        in.send(new GenericMessage<>("ready!"));

    }
}


@Configuration
@Slf4j
public class ExceptionTypeRouter {

    @Bean
    @Qualifier("inDefaultChannel")
    public DirectChannel inDefaultChannel() {
        return MessageChannels
                .direct()
                .get();
    }

    @Bean
    @Qualifier("directErrorChannel")
    public DirectChannel directErrorChannel() {
        return MessageChannels
                .direct()
                .get();
    }

    @Bean
    public ErrorMessageExceptionTypeRouter errorMessageExceptionTypeRouter() {
        ErrorMessageExceptionTypeRouter router = new ErrorMessageExceptionTypeRouter();
        router.setChannelMapping(IOException.class.getName(), "directErrorChannel");
        router.setChannelMapping(NullPointerException.class.getName(), "directErrorChannel");
        router.setDefaultOutputChannel(outDefaultChannel());

        return router;
    }
}    

The proplem is somwhere here. Caze this.getApplicationContext() is null.

 private Class<?> resolveClassFromName(String className) {
        try {
            return ClassUtils.forName(className, this.getApplicationContext().getClassLoader());
        } catch (ClassNotFoundException var3) {
            throw new IllegalStateException("Cannot load class for channel mapping.", var3);
        }
    }

Error log:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'errorMessageExceptionTypeRouter' defined in integration.exceptiondemo.configuration.router.ExceptionTypeRouter: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework. integration.router.ErrorMessageExceptionTypeRouter]: Factory method 'errorMessageExceptionTypeRouter' threw exception; nested exception is java.lang.NullPointerException

Answer 1

Agreed. That's bug in the ErrorMessageExceptionTypeRouter.

When you call setChannelMapping() it doesn't check for the this.initialized and try to call the mentioned resolveClassFromName() when we don't have ApplicationContext populated yet.

Please, raise a JIRA to fix it: https://jira.spring.io/projects/INT

Meanwhile as a workaround you should consider to use setChannelMappings(Map<String, String>) instead:

@Bean
public ErrorMessageExceptionTypeRouter errorMessageExceptionTypeRouter() {
    ErrorMessageExceptionTypeRouter router = new ErrorMessageExceptionTypeRouter();
    Map<String, String> mappings = new HashMap<>();
    mappings.put(IOException.class.getName(), "directErrorChannel");
    mappings.put(NullPointerException.class.getName(), "directErrorChannel");
    router.setChannelMappings(mappings);
    router.setDefaultOutputChannel(outDefaultChannel());

    return router;
}