how to add RequestMappingHandlerMapping and ResourceHandlers to a springMVC configuration class

I didn't get from your question why you can't use WebMvcConfigurationSupport. If by what you mentioned "...unfortunatly i have already extended WebMvcConfigurationSupport class for resource's mapping..." you rather meant that you've already extended the WebMvcConfigurerAdapter, you should be aware that WebMvcConfigurationSupport exposes exactly the same method.

Anyways, following should be a working java config for Spring MVC 3.1 version

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurationSupport {

    @Override
    @Bean
    public RequestMappingHandlerMapping requestMappingHandlerMapping() {
        RequestMappingHandlerMapping hm = super.requestMappingHandlerMapping();
        hm.setUseSuffixPatternMatch(false);
        return hm;
    }

    @Bean
    public InternalResourceViewResolver configureInternalResourceViewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        return resolver;
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations(
                "/resources/");
    }
}

Overriding requestMappingHandlerMapping using WebMvcConfigurationSupport, may turn off your spring boot's default configurations. A better way could be to use WebMvcRegistrations as,

@Configuration
static class CustomRequestMappingHandlerMapping {

    @Bean
    public WebMvcRegistrationsAdapter webMvcRegistrationsHandlerMapping() {
        return new WebMvcRegistrationsAdapter() {
            @Override
            public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
                return new MyRequestMappingHandlerMapping();
            }
        };
    }
}

And since Spring Boot 2.0.0 you could use WebMvcRegistrations directly

@Configuration
public class WebMvcConfig  {
    @Bean
    public WebMvcRegistrations webMvcRegistrationsHandlerMapping() {
        return new WebMvcRegistrations() {
            @Override
            public RequestMappingHandlerMapping getRequestMappingHandlerMapping() {
                return new CustomRequestMappingHandlerMapping();
            }
        };
    }
}