Little class to upload a binary file to an http server

FileUploader.java

import java.io.BufferedInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Reader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.nio.file.Files;

// For https://www.reddit.com/r/javahelp/comments/hjzr16/javagroovy_script_for_uploading_a_file_in_chunks/

public class FileUploader {

    // From: https://stackoverflow.com/questions/2469451/upload-files-from-java-client-to-a-http-server

    public static void main(String[] args) throws Exception {
        String url = "https://httpbin.org/post";
        String charset = "UTF-8";
        File binaryFile = new File("lil_file.pro");
        String boundary = Long.toHexString(System.currentTimeMillis()); // Just generate some unique random value.
        String CRLF = "\r\n"; // Line separator required by multipart/form-data.

        URLConnection connection = new URL(url).openConnection();
        connection.setDoOutput(true);
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);

        // Using the try with ressource construct
        try (OutputStream output = connection.getOutputStream();
                PrintWriter writer = new PrintWriter(new OutputStreamWriter(output, charset), true);) {

            // Send binary file.
            writer.append("--" + boundary).append(CRLF);
            writer.append(
                    "Content-Disposition: form-data; name=\"binaryFile\"; filename=\"" + binaryFile.getName() + "\"")
                    .append(CRLF);
            writer.append("Content-Type: " + URLConnection.guessContentTypeFromName(binaryFile.getName())).append(CRLF);
            writer.append("Content-Transfer-Encoding: binary").append(CRLF);
            writer.append(CRLF).flush();
            Files.copy(binaryFile.toPath(), output);
            output.flush(); // Important before continuing with writer!
            writer.append(CRLF).flush(); // CRLF is important! It indicates end of boundary.

            // End of multipart/form-data.
            writer.append("--" + boundary + "--").append(CRLF).flush();
        }

        // Request is lazily fired whenever you need to obtain information about
        // response.
        int responseCode = ((HttpURLConnection) connection).getResponseCode();
        System.out.println(responseCode); // Should be 200
        printFromStream(((HttpURLConnection) connection).getInputStream());
    }

    // From: Java Network Programming, 4th Edition. by Elliotte Rusty Harold p.234 
    private static void printFromStream(InputStream raw) throws IOException {
        try (InputStream buffer = new BufferedInputStream(raw)) {
            Reader reader = new InputStreamReader(buffer);
            int c;
            while ((c = reader.read()) != -1) {
                System.out.print((char) c);
            }
        }
    }

}

lil_file.pro

mortal(X):-person(X).
person(plato).
person(socrate).
person(zeno).
person(aristototle).

mortal_report:-
    write("Known mortals are"),nl,
    mortal(X),
    write(X),nl,
    fail.

sample_console_output.txt

200
{
  "args": {},
  "data": "",
  "files": {
    "binaryFile": "mortal(X):-person(X).\r\nperson(plato).\r\nperson(socrate).\r\nperson(zeno).\r\nperson(aristototle).\r\n\r\nmortal_report:-\r\n    write(\"Known mortals are\"),nl,\r\n    mortal(X),\r\n    write(X),nl,\r\n    fail.\r\n\r\n"
  },
  "form": {},
  "headers": {
    "Accept": "text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2",
    "Content-Length": "363",
    "Content-Type": "multipart/form-data; boundary=173113555f4",
    "Host": "httpbin.org", 
    "User-Agent": "Java/1.8.0_252",
    "X-Amzn-Trace-Id": "Root=1-5efe42e7-53ca46de7ee58a318cdd0e2a"
  }, 
  "json": null,
  "origin": "105.300.51.17",
  "url": "https://httpbin.org/post"
}