Network

Network.java

public final class Network {
  private Network() {
  }

  public static @NonNull String doGetRequest(@NonNull String service, @NonNull String resource,
      @NonNull List<Pair<String, String>> params, @NonNull List<Pair<String, String>> headers) throws IOException {
    HttpURLConnection httpURLConnection = null;
    try {
      URL url = new URL(
          service + "/" + Uri.encode(resource) + (params.isEmpty() ? "" : "&" + convertPairToParamString(params)));
      httpURLConnection = (HttpURLConnection) url.openConnection();
      httpURLConnection.setRequestMethod("GET");
      makeHeaders(httpURLConnection, headers);
      httpURLConnection.connect();
      return convertStreamToString(httpURLConnection.getInputStream());
    } catch (Exception e) {
      throw new IOException();
    } finally {
      if (httpURLConnection != null) {
        httpURLConnection.disconnect();
      }
    }
  }

  public static @NonNull String doPostRequest(@NonNull String service, @NonNull String resource,
      @NonNull List<Pair<String, String>> params, @NonNull List<Pair<String, String>> headers) throws IOException {
    HttpURLConnection httpURLConnection = null;
    try {
      URL url = new URL(service + "/" + Uri.encode(resource));
      httpURLConnection = (HttpURLConnection) url.openConnection();
      httpURLConnection.setRequestMethod("POST");
      makeHeaders(httpURLConnection, headers);
      OutputStreamWriter writer = new OutputStreamWriter(httpURLConnection.getOutputStream());
      writer.write(convertPairToParamString(params));
      writer.close();
      httpURLConnection.connect();
      return convertStreamToString(httpURLConnection.getInputStream());
    } catch (Exception e) {
      throw new IOException();
    } finally {
      if (httpURLConnection != null) {
        httpURLConnection.disconnect();
      }
    }
  }

  private static void makeHeaders(@NonNull HttpURLConnection httpURLConnection,
      @NonNull List<Pair<String, String>> headers) {
    for (Pair<String, String> pair : headers) {
      httpURLConnection.setRequestProperty(pair.first, pair.second);
    }
  }

  private static @NonNull String convertPairToParamString(List<Pair<String, String>> params) {
    StringBuilder result = new StringBuilder();
    boolean first = true;

    for (Pair<String, String> pair : params) {
      if (first) {
        first = false;
      } else {
        result.append("&");
      }

      result.append(Uri.encode(pair.first));
      result.append("=");
      result.append(Uri.encode(pair.second));
    }
    return result.toString();
  }

  private static @NonNull String convertStreamToString(@NonNull InputStream inputStream) throws IOException {
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
    StringBuilder stringBuilder = new StringBuilder();
    String line;
    try {
      while ((line = bufferedReader.readLine()) != null) {
        stringBuilder.append(line).append("\n");
      }
    } catch (IOException e) {
      throw new IOException();
    } finally {
      try {
        inputStream.close();
      } catch (IOException ignored) {
      }
    }
    return stringBuilder.toString();
  }
}