simple java file upload server

FileUploadServer

#!/usr/bin/java --source 21

import java.io.*;
import java.net.*;
import java.nio.file.*;

import com.sun.net.httpserver.*;

public class FileUploadServer implements HttpHandler {
	public static void main(String[] args) throws IOException {
		if (args.length != 2) {
			System.out.printf("Usage:  %s <port> <root>%n", FileUploadServer.class.getName());
			System.exit(1);
		}

		var root = Path.of(args[1]);
		var port = Integer.parseInt(args[0]);

		if (!Files.isDirectory(root)) {
			System.out.printf("Root %s is not a directory%n", root);
			System.exit(1);
		}

		var server = HttpServer.create();

		server.createContext("/", new FileUploadServer(root));
		server.bind(new InetSocketAddress(port), 0);
		server.start();
	}

	private final Path root;
	private final HttpHandler delegate;

	public FileUploadServer(Path root) {
		this.root = root;
		this.delegate = SimpleFileServer.createFileHandler(root.toAbsolutePath());
	}

	private void handlePut(HttpExchange exchange) throws IOException {
		try (exchange) {
			URI accessibleURL;
			Path destination;

			if (exchange.getRequestURI().getPath().equals("/") || exchange.getRequestURI().getPath().isEmpty()) {
				var filename = randomAlphaNumeric(10);
				destination = root.resolve(filename);
				accessibleURL = exchange.getRequestURI().resolve(filename);
			} else {
				destination = root.resolve(exchange.getRequestURI().getPath());
				accessibleURL = exchange.getRequestURI();
			}

			Files.createDirectories(destination.getParent());
			Files.write(destination, exchange.getRequestBody().readAllBytes());

			System.out.println(accessibleURL);
			if (accessibleURL.getHost() == null)
				accessibleURL = new URI("http", null, exchange.getLocalAddress().getHostName(), exchange.getLocalAddress().getPort(), accessibleURL.getPath(), null, null);

			exchange.sendResponseHeaders(201, accessibleURL.toString().length());
			exchange.getResponseBody().write(accessibleURL.toString().getBytes());
		} catch (URISyntaxException e) {
			throw new RuntimeException(e);
		}
	}

	@Override
	public void handle(HttpExchange exchange) throws IOException {
		switch (exchange.getRequestMethod()) {
			case "GET" -> delegate.handle(exchange);
			case "PUT" -> handlePut(exchange);
		}
	}

	private static String randomAlphaNumeric(int count) {
		var builder = new StringBuilder();
		for (int i = 0; i < count; i++) {
			builder.append((char) (Math.random() * 26 + 'a'));
		}
		return builder.toString();
	}
}