Spring Boot 2 - request mapping with wildcard parameter (/path/**)

In this short article, we would like to show how to get wildcard request parameters (under stars parameter from /some/path/**) from URL in Spring Boot 2.

Quick solution:

package example.controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.PathMatcher;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.HandlerMapping;

import javax.servlet.http.HttpServletRequest;

@Controller
public class ExampleController {

    @Autowired
    private PathMatcher pathMatcher;

    private String getWildcardParam(HttpServletRequest request) {
        String patternAttribute = (String) request.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
        String mappingAttribute = (String) request.getAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE);
        return this.pathMatcher.extractPathWithinPattern(patternAttribute, mappingAttribute);
    }

    @RequestMapping(
            method = RequestMethod.GET,
            value = "/items/{itemId}/**"
    )
    public ResponseEntity<String> getItem(HttpServletRequest request, @PathVariable String itemId) {
        String wildcardParam = this.getWildcardParam(request);  // <--- extracts all data located under **

        // Some logic here ...
    }
}

Reusable @WildcardParam annotation

This section contains an example source code, how to create and use simple @WildcardParam annotation.

Simple steps:

1. create wildcard annotation to simplify controller mappings usage,
2. register wildcard annotation in application configuration,
3. use wildcard parameters in @PathVariable way.

ExampleController.java file:

package example.controllers;

import example.annotations.WildcardParam;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.HandlerMapping;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.Part;
import java.io.IOException;
import java.net.URISyntaxException;
import java.util.Collection;
import java.util.function.Function;

@Controller
public class ExampleController {

    @RequestMapping(
            method = RequestMethod.GET,
            value = "/items/{itemId}/**"
    )
    public ResponseEntity<String> getItem(
            @PathVariable String itemId,
            @WildcardParam String itemResource  // <--- contains all data located under **
    ) {
        // Some logic here ...
    }
}

WildcardParam.java file:

package example.annotations;

import org.springframework.core.MethodParameter;
import org.springframework.util.PathMatcher;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import org.springframework.web.servlet.HandlerMapping;

import javax.servlet.http.HttpServletRequest;
import java.lang.annotation.*;

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
public @interface WildcardParam {

    class Resolver implements HandlerMethodArgumentResolver {

        private PathMatcher pathMatcher;

        public Resolver(PathMatcher pathMatcher) {
            this.pathMatcher = pathMatcher;
        }

        @Override
        public boolean supportsParameter(MethodParameter methodParameter) {
            Annotation annotation = methodParameter.getParameterAnnotation(WildcardParam.class);
            return annotation != null;
        }

        @Override
        public Object resolveArgument(MethodParameter methodParameter, ModelAndViewContainer modeContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
            HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
            if (servletRequest == null) {
                return null;
            }
            String patternAttribute = (String) servletRequest.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
            String mappingAttribute = (String) servletRequest.getAttribute(HandlerMapping.PATH_WITHIN_HANDLER_MAPPING_ATTRIBUTE);
            return this.pathMatcher.extractPathWithinPattern(patternAttribute, mappingAttribute);
        }
    }
}

MVCConfig.java file:

package example.config;

import example.annotations.WildcardParam;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.PathMatcher;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import java.util.List;

@Configuration
public class MVCConfig implements WebMvcConfigurer {

    @Autowired
    private PathMatcher pathMatcher;  // or replace it with bean creation function

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
        resolvers.add(new WildcardParam.Resolver(this.pathMatcher));
    }
}

See also

1. Spring Boot 2 - request mapping with not decoded PathVariable (/path/{pathVariable})