Add exports for dynamic layers

FeatureRichLayerCreation.java

/*
 * For modules on the boot-layer one can add exports using --add-exports but it looks like there's no
 * public API to do the same when constructing a custom layer
 */
package javamodules;

import java.lang.ModuleLayer.Controller;
import java.lang.module.Configuration;
import java.lang.module.ModuleFinder;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;


public class FeatureRichLayerCreation {

	private static Path JAVAFX_MODULES = Paths.get("/Users/tomschindl/Downloads/javafx-sdk-11/lib");

	@SuppressWarnings("deprecation")
	public static void main(String[] args) throws Throwable {
		System.err.println("VERSION: " + System.getProperty("java.version"));
		Path[] array = Files.list(JAVAFX_MODULES) //
				.filter(p -> {
					String name = p.getFileName().toString();
					return name.startsWith("javafx.") && name.endsWith(".jar");
				}) //
				.toArray(i -> new Path[i]);
		Set<String> modules = Stream.of(array) //
				.map(Path::getFileName) //
				.map(Path::toString) //
				.map(n -> n.substring(0, n.length() - ".jar".length())) //
				.collect(Collectors.toSet());
		
		URL[] urls = Stream.of(array).map( Path::toFile).map( f -> {
			try {
				return f.toURL();
			} catch(Throwable t) {
				return null;	
			}
		} ).toArray( i -> new URL[i]);
		
		
		URLClassLoader c = new URLClassLoader(urls, FeatureRichLayerCreation.class.getClassLoader()) {
			protected java.lang.Class<?> findClass(String moduleName, String name) {
				try {
					return findClass(name);	
				} catch (ClassNotFoundException e) {}
				return null;
			}
			
			protected URL findResource(String moduleName, String name) throws java.io.IOException {
				return findResource(name);
			}
		};

		ModuleFinder fxModuleFinder = ModuleFinder.of(array);
		ModuleFinder empty = ModuleFinder.of(new Path[0]);
		ModuleLayer bootLayer = ModuleLayer.boot();
		Configuration configuration = bootLayer.configuration();
		Configuration newConfiguration = configuration.resolve(fxModuleFinder, empty, modules);
		
		Controller moduleLayerController = ModuleLayer.defineModules(newConfiguration, Arrays.asList(bootLayer), s -> c);
		ModuleLayer moduleLayer = moduleLayerController.layer();
		
		moduleLayerController.addExports(moduleLayer.findModule("javafx.base").get(), "com.sun.javafx.runtime", FeatureRichLayerCreation.class.getModule());
		
		ClassLoader loader = moduleLayer.findLoader("javafx.base");
		
		System.err.println(loader.loadClass("javafx.beans.property.SimpleStringProperty").newInstance());
		System.err.println(loader.loadClass("com.sun.javafx.runtime.VersionInfo").newInstance());
		Class<?> loadClass = loader.loadClass("com.sun.glass.utils.NativeLibLoader");
		System.err.println(loadClass.getModule());
		
		// we need to overwrite findResource(String,String)
		System.err.println(loadClass.getResource("NativeLibLoader.class"));
		// we need to overwrite findClass(String,String)
		System.err.println(Class.forName(moduleLayer.findModule("javafx.base").get(), "javafx.beans.property.SimpleIntegerProperty"));
		
		
		c.close();
	}
}