Main.java

package xyz.behrang.uploader;

import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpRequest.BodyPublisher;
import java.net.http.HttpRequest.BodyPublishers;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Duration;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class package xyz.behrang.uploader;

import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpRequest.BodyPublisher;
import java.net.http.HttpRequest.BodyPublishers;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.time.Duration;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class Main {
    public static void main(String[] args) {
        final var threadCount = 2;
        final var threads = new ArrayList<Thread>();

        for (int i = 0; i < threadCount; i++) {
            threads.add(new Thread(new Uploader()));
        }

        threads.forEach(Thread::start);
        threads.forEach(t -> {
            try {
                t.join();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        });
    }
}

class Uploader implements Runnable {

    @Override
    public void run() {
        try {
            final var client =
                    HttpClient.newBuilder()
                              .connectTimeout(Duration.ofSeconds(10))
                              .version(HttpClient.Version.HTTP_1_1)
                              .build();

            final var body = new HashMap<>();
            body.put("document", Paths.get("/home/behrangsa/Data/arxiv/arXiv_pdf_0001_001.tar"));

            final var request =
                    HttpRequest.newBuilder()
                               .uri(URI.create("http://localhost:8080/file-server/sync/upload"))
                               .header("Content-Type", "multipart/form-data; boundary=foobarbaz")
                               .timeout(Duration.ofSeconds(10))
                               .POST(ofMimeMultipartData(body, "foobarbaz"))
                               .build();

            final var response = client.send(request, HttpResponse.BodyHandlers.ofString());

            System.out.println(response.statusCode());
            System.out.println(response.body());
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    // Copied from https://github.com/ralscha/blog2019/blob/master/java11httpclient/client/src/main/java/ch/rasc/httpclient/File.java#L69-L92
    public static BodyPublisher ofMimeMultipartData(Map<Object, Object> data, String boundary) throws IOException {
        final var byteArrays = new ArrayList<byte[]>();
        final var separator = ("--" + boundary + "\r\nContent-Disposition: form-data; name=").getBytes(StandardCharsets.UTF_8);
        for (final var entry : data.entrySet()) {
            byteArrays.add(separator);

            if (entry.getValue() instanceof Path) {
                var path = (Path) entry.getValue();
                String mimeType = Files.probeContentType(path);
                byteArrays.add(("\"" + entry.getKey() + "\"; filename=\"" + path.getFileName()
                                + "\"\r\nContent-Type: " + mimeType + "\r\n\r\n").getBytes(StandardCharsets.UTF_8));
                byteArrays.add(Files.readAllBytes(path));
                byteArrays.add("\r\n".getBytes(StandardCharsets.UTF_8));
            } else {
                byteArrays.add(("\"" + entry.getKey() + "\"\r\n\r\n" + entry.getValue() + "\r\n").getBytes(StandardCharsets.UTF_8));
            }
        }

        byteArrays.add(("--" + boundary + "--").getBytes(StandardCharsets.UTF_8));

        return BodyPublishers.ofByteArrays(byteArrays);
    }
} {
    public static void main(String[] args) {
        final var threadCount = 2;
        final var threads = new ArrayList<Thread>();

        for (int i = 0; i < threadCount; i++) {
            threads.add(new Thread(new Uploader()));
        }

        threads.forEach(Thread::start);
        threads.forEach(t -> {
            try {
                t.join();
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        });
    }
}

class Uploader implements Runnable {

    @Override
    public void run() {
        try {
            final var client =
                    HttpClient.newBuilder()
                              .connectTimeout(Duration.ofSeconds(10))
                              .version(HttpClient.Version.HTTP_1_1)
                              .build();

            final var body = new HashMap<>();
            body.put("document", Paths.get("/home/behrangsa/Data/arxiv/arXiv_pdf_0001_001.tar"));

            final var request =
                    HttpRequest.newBuilder()
                               .uri(URI.create("http://localhost:8080/file-server/sync/upload"))
                               .header("Content-Type", "multipart/form-data; boundary=foobarbaz")
                               .timeout(Duration.ofSeconds(10))
                               .POST(ofMimeMultipartData(body, "foobarbaz"))
                               .build();

            final var response = client.send(request, HttpResponse.BodyHandlers.ofString());

            System.out.println(response.statusCode());
            System.out.println(response.body());
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    // Copied from https://github.com/ralscha/blog2019/blob/master/java11httpclient/client/src/main/java/ch/rasc/httpclient/File.java#L69-L92
    public static BodyPublisher ofMimeMultipartData(Map<Object, Object> data, String boundary) throws IOException {
        final var byteArrays = new ArrayList<byte[]>();
        final var separator = ("--" + boundary + "\r\nContent-Disposition: form-data; name=").getBytes(StandardCharsets.UTF_8);
        for (final var entry : data.entrySet()) {
            byteArrays.add(separator);

            if (entry.getValue() instanceof Path) {
                var path = (Path) entry.getValue();
                String mimeType = Files.probeContentType(path);
                byteArrays.add(("\"" + entry.getKey() + "\"; filename=\"" + path.getFileName()
                                + "\"\r\nContent-Type: " + mimeType + "\r\n\r\n").getBytes(StandardCharsets.UTF_8));
                byteArrays.add(Files.readAllBytes(path));
                byteArrays.add("\r\n".getBytes(StandardCharsets.UTF_8));
            } else {
                byteArrays.add(("\"" + entry.getKey() + "\"\r\n\r\n" + entry.getValue() + "\r\n").getBytes(StandardCharsets.UTF_8));
            }
        }

        byteArrays.add(("--" + boundary + "--").getBytes(StandardCharsets.UTF_8));

        return BodyPublishers.ofByteArrays(byteArrays);
    }
}