Springboot/Angular2 – How to handle HTML5 urls?

In my Spring Boot applications (version 1 and 2), my static resources are at a single place :

src/main/resources/static

static being a folder recognized by Spring Boot to load static resources.

Then the idea is to customize the Spring MVC configuration.
The simpler way is using Spring Java configuration.

I implement WebMvcConfigurer to override addResourceHandlers().
I add in a single ResourceHandler to the current ResourceHandlerRegistry.
The handler is mapped on every request and I specify classpath:/static/ as resource location value (you may of course adding others if required).
I add a custom PathResourceResolver anonymous class to override getResource(String resourcePath, Resource location).
And the rule to return the resource is the following : if the resource exists and is readable (so it is a file), I return it. Otherwise, by default I return the index.html page. Which is the expected behavior to handle HTML 5 urls.

Spring Boot 1.X Application :

Extending org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter is the way.
The class is an adapter of the WebMvcConfigurer interface
with empty methods allowing sub-classes to override only the methods they’re interested in.

Here is the full code :

import java.io.IOException;

import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
import org.springframework.web.servlet.resource.PathResourceResolver;

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {

       
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

    registry.addResourceHandler("/**/*")
        .addResourceLocations("classpath:/static/")
        .resourceChain(true)
        .addResolver(new PathResourceResolver() {
            @Override
            protected Resource getResource(String resourcePath,
                Resource location) throws IOException {
                  Resource requestedResource = location.createRelative(resourcePath);
                  return requestedResource.exists() && requestedResource.isReadable() ? requestedResource
                : new ClassPathResource("/static/index.html");
            }
        });
    }
}

Spring Boot 2.X Application :

org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter was deprecated.
Implementing directly WebMvcConfigurer is the way now as it is still an interface but it has now default methods (made possible by a Java 8 baseline) and can be implemented directly without the need for the adapter.

Here is the full code :

import java.io.IOException;

import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.resource.PathResourceResolver;

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

      registry.addResourceHandler("/**/*")
        .addResourceLocations("classpath:/static/")
        .resourceChain(true)
        .addResolver(new PathResourceResolver() {
            @Override
            protected Resource getResource(String resourcePath,
                Resource location) throws IOException {
                Resource requestedResource = location.createRelative(resourcePath);
                return requestedResource.exists() && requestedResource.isReadable() ? requestedResource
                : new ClassPathResource("/static/index.html");
            }
        });
    }
}

EDIT to address some comments :

For those that store their static resources at another location as src/main/resources/static, change the value of the var args parameter of addResourcesLocations() consequently.
For example if you have static resources both in static and in the public folder (no tried) :

  registry.addResourceHandler("/**/*")
    .addResourceLocations("classpath:/static/", "/public")