How to convert a subdomain to a path with Embedded Tomcat 8 and Spring boot

Question

How to rewrite subdomains to paths?

Example:

• foo.bar .example.com --> example.com /foo/bar

Or better woul

Answer 1

Another way to solve this issue: Do it in Controller itself. This is in my opinion better way than with filter because:

• filter catches every request. Here you can better controll which requests should be delivered with 'subdomain pattern'. As example I've choosen /subdomain2path.
• You don't have to change/wrap URI/URLs and forward via filter chain again.
• All logic is in this controller

Methods getSubdomain and reverseDomain are same as in answer before.

This is the impl:

@RestController
@RequestMapping("/subdomain2path")
public class Subdomain2PathController {

    @RequestMapping("/")
    public FileSystemResource deliver(final HttpServletRequest request) {
        final Domain subdomain = getSubdomain(request.getServerName());

        String file = "/";
        if (subdomain.hasSubdomain()) {
            file = subdomain.getSubdomainAsPath();
        }

        return new FileSystemResource(getStaticFile(file));
    }

    private Domain getSubdomain(final String domain) {
        final String[] domainParts = domain.split("\\.");
        String mainDomain;
        String subDomain = null;

        final int dpLength = domainParts.length;
        if (dpLength > 2) {
            mainDomain = domainParts[dpLength - 2] + "." + domainParts[dpLength - 1];

            subDomain = reverseDomain(domainParts);
        } else {
            mainDomain = domain;
        }

        return new Domain(mainDomain, subDomain);
    }

    private String reverseDomain(final String[] domainParts) {
        final List subdomainList = Arrays.stream(domainParts, 0, domainParts.length - 2)//
                .collect(Collectors.toList());

        Collections.reverse(subdomainList);

        return subdomainList.stream().collect(Collectors.joining("."));
    }

    private File getStaticFile(final String path) {
        try {
            // TODO handle correct
            return new File(Subdomain2PathController.class.getResource("/static/" + path + "/index.html").toURI());
        } catch (final Exception e) {
            throw new RuntimeException("not found");
        }
    }
}

Domain class is same as in answer before:

public static class Domain {
    private final String maindomain;
    private final String subdomain;

    public Domain(final String maindomain, final String subdomain) {
        this.maindomain = maindomain;
        this.subdomain = subdomain;
    }

    public String getMaindomain() {
        return maindomain;
    }

    public String getSubdomain() {
        return subdomain;
    }

    public boolean hasSubdomain() {
        return subdomain != null;
    }

    public String getSubdomainAsPath() {
        return "/" + subdomain.replaceAll("\\.", "/") + "/";
    }
}