public WebFile getFile(String fileName) {
		Matcher m = ext.matcher(fileName);
		if(m.matches()) {
			String g1 = m.group(1);
			if(theMap.containsKey(g1)) {
				try {
					return theMap.get(g1).getDeclaredConstructor(String.class).newInstance(fileName);
				} catch (Exception e) {
					System.out.println("FUBAR");
				}
			}
		}
		return null;
	}

Pattern ext = Pattern.compile(".*\\.(.+)");

package server;

import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.reflections.Reflections;

public class WebFileFactory {
	private static Map<String, Class<? extends WebFile>> theMap;
	private static final Pattern ext = Pattern.compile(".*\\.(.+)");

	static {
		Reflections reflections = new Reflections("server.fileTypes");
		Set<Class<? extends WebFile>> subtypes = reflections.getSubTypesOf(WebFile.class);

package server.fileTypes;

import server.Types;
import server.WebFile;

import java.io.File;
import java.util.List;

@Types ( knownTypes = {"txt", "text"} )
public class TextFile implements WebFile {
	public TextFile(String file) {

	}


	@Override
	public WebFile createWebFile(File f) {
		return null;
	}

	@Override
	public List<String> getFileTypes() {
		return null;
	}

	@Override
	public String getStatusLine() {
		return null;
	}

	@Override
	public String getEntityHeader() {
		return null;

package server;

import org.junit.Test;
import server.fileTypes.TextFile;

import static org.junit.Assert.assertTrue;

public class WebFileFactoryTest {
	@Test
	public void testGetFile() throws Exception {
		WebFile file = WebFileFactory.getFile("foo.txt");
		assertTrue(file instanceof TextFile);
	}
}

import static org.junit.Assert.assertTrue;