URLConnectionHttpClientWrapper.java

/*
 * Copyright (C) 2021 B3Partners B.V.
 *
 * SPDX-License-Identifier: MIT
 *
 */

package nl.b3p.brmo.util.http.wrapper;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URLConnection;
import nl.b3p.brmo.util.http.HttpClientWrapper;
import nl.b3p.brmo.util.http.HttpResponseWrapper;

/**
 * Wraps a standard Java HttpURLConnection or HttpsURLConnection.
 *
 * @author Matthijs Laan
 */
public class URLConnectionHttpClientWrapper
    implements HttpClientWrapper<HttpURLConnection, HttpURLConnection> {
  @Override
  public HttpResponseWrapper request(URI uri, String... requestHeaders) throws IOException {
    URLConnection connection = uri.toURL().openConnection();
    if (!(connection instanceof HttpURLConnection)) {
      throw new IllegalArgumentException("Expected HttpURLConnection instance for URI " + uri);
    }
    HttpURLConnection httpURLConnection = (HttpURLConnection) connection;
    httpURLConnection.setInstanceFollowRedirects(true);
    if (requestHeaders.length % 2 != 0) {
      throw new IllegalArgumentException();
    }
    for (int i = 0; i < requestHeaders.length; i += 2) {
      httpURLConnection.setRequestProperty(requestHeaders[i], requestHeaders[i + 1]);
    }

    beforeRequest(httpURLConnection);
    httpURLConnection.connect();

    return wrapResponse(httpURLConnection);
  }

  /**
   * Called before doing a request, override to modify or log it.
   *
   * @param httpURLConnection The HttpURLConnection that will be used, can be modified
   */
  @Override
  public void beforeRequest(HttpURLConnection httpURLConnection) {}

  /**
   * Wraps a HttpURLConnection after HttpURLConnection.connect() has been called, override to modify
   * or log it.
   *
   * @param httpURLConnection The URL connection to be wrapped
   * @return The wrapped response
   */
  @Override
  public HttpResponseWrapper wrapResponse(HttpURLConnection httpURLConnection) {
    return new HttpResponseWrapper() {
      @Override
      public int getStatusCode() throws IOException {
        return httpURLConnection.getResponseCode();
      }

      @Override
      public String getHeader(String header) {
        return httpURLConnection.getHeaderField(header);
      }

      @Override
      public InputStream getResponseBody() throws IOException {
        return httpURLConnection.getInputStream();
      }
    };
  }
}