Java:
基本認証を使用したHTTPリクエストの送信

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.util.Base64;

String username = "user";
String password = "pass";
String encodedCredentials = Base64.getEncoder().encodeToString((username + ":" + password).getBytes());

HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
        .uri(URI.create("http://example.com"))
        .header("Authorization", "Basic " + encodedCredentials)
        .build();

client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
        .thenApply(HttpResponse::body)
        .thenAccept(System.out::println)
        .join();