Snippet

Custom HandlerMethodArgumentResolver for Clean Controllers

Custom argument resolvers allow you to automatically inject complex objects into controller methods based on request data like headers or session attributes. This keeps your controllers clean and removes repetitive boiler-plate code for extracting common data.

snippet.java

java

@Component
public class UserContextResolver implements HandlerMethodArgumentResolver {
    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.getParameterType().equals(UserContext.class);
    }
 
    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavc, NativeWebRequest request, WebDataBinderFactory dbf) {
        String userId = request.getHeader("X-User-ID");
        return new UserContext(userId);
    }
}
 
@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Autowired private UserContextResolver userContextResolver;
    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
        resolvers.add(userContextResolver);
    }
}

spring

Breakdown

supportsParameter(MethodParameter parameter)

Checks if the resolver supports the specific method parameter type.

resolveArgument(...)

The logic to extract data from the request and construct the argument object.

addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers)

Registers the custom resolver within the Spring MVC configuration.

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Custom HandlerMethodArgumentResolver for Clean Controllers

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