Java 8+ HTTP Client.

HttpClient.java

import io.swagger.v3.oas.models.PathItem.HttpMethod;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.stream.Collectors;
import lombok.NoArgsConstructor;
import lombok.SneakyThrows;
import lombok.extern.java.Log;
import lombok.val;

/**
 * Utility HTTP 1.1 client for requesting to other external API.
 */
@Log
@NoArgsConstructor(staticName = "create")
public class HttpClient {

  /**
   * Extracts the content requested from a URL.
   *
   * @param url The URL to source from.
   * @return The extraction content in string form.
   * @since 1.0-SNAPSHOT.
   */
  @SneakyThrows
  public String sourceFrom(final String url) {
    val conn = (HttpURLConnection) new URL(url).openConnection();
    conn.setRequestMethod(HttpMethod.GET.name());

    if (conn.getResponseCode() != HttpURLConnection.HTTP_OK) {
      throw new IllegalStateException(
        "Not satisfiable status code: [" + conn.getResponseCode() + "]");
    }

    try (val stream = new BufferedReader(
      new InputStreamReader(conn.getInputStream()))) {
      return stream.lines().collect(Collectors.joining());
    }
  }