Configure additional, dynamic paths to be delivered as static content by Spring Boot in addition to the default static content.

ExtResourcesConfig.java

package com.example.demo;

import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class ExtResourcesConfig {

	public static final class PrefixAndLocation {

		private String path;
		private String location;

		public String getPath() {
			return path;
		}

		public void setPath(String path) {
			this.path = path;
		}

		public String getLocation() {
			return location;
		}

		public void setLocation(String location) {
			this.location = location;
		}
	}

	/**
	 * Use with
	 * <p>
	 * <code>
	 *     ms.additional-resources[0].path = /x/**
	 *     ms.additional-resources[0].location = file:///Users/msimons/tmp/r/
	 * </code>
	 */
	@ConfigurationProperties(prefix = "ms")
	public static class ExResourcesProperties {

		List<PrefixAndLocation> additionalResources = List.of();

		public List<PrefixAndLocation> getAdditionalResources() {
			return additionalResources;
		}

		public void setAdditionalResources(List<PrefixAndLocation> additionalResources) {
			this.additionalResources = additionalResources;
		}
	}

	Logger logger = Logger.getLogger(ExtResourcesConfig.class.getName());

	@Bean
	ExResourcesProperties exResourcesProperties() {
		return new ExResourcesProperties();
	}

	@Bean
	WebMvcConfigurer registerAdditionalResources(@Autowired ExResourcesProperties properties) {

		return new WebMvcConfigurer() {
			@Override public void addResourceHandlers(ResourceHandlerRegistry registry) {
				if (properties.additionalResources.isEmpty()) {
					return;
				}
				properties.additionalResources.forEach(resource -> {
					logger.log(Level.INFO, "Adding {0} with location {1}", new Object[] { resource.getPath(), resource.getLocation() });
					registry.addResourceHandler(resource.getPath()).addResourceLocations(resource.getLocation());
				});
			}
		};
	}
}