Java class to get the audio features of some songs from Spotify's official API.

SpotiDump.java

package eus.unai.spotidump;

import com.google.gson.Gson;
import com.google.gson.internal.LinkedTreeMap;
import com.opencsv.CSVReader;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import java.io.FileReader;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.*;
import java.util.stream.Collectors;

public class SpotiDump {

    private static final String ACCESS_TOKEN = System.getenv("ACCESS_TOKEN");

    private static final String TRACK_URL = "https://open.spotify.com/track/";
    private static final String GET_TRACKS = "https://api.spotify.com/v1/tracks/?ids=";
    private static final String GET_ALBUMS = "https://api.spotify.com/v1/albums/?ids=";
    private static final String GET_FEATURES = "https://api.spotify.com/v1/audio-features/";

    private static final Integer LOOP_SIZE = 11;

    public static void main(String [] args) throws Exception {
        Set<String> idSet = new HashSet<>();
        try (CSVReader csvReader = new CSVReader(new FileReader("daily-200.csv"))) {
            Iterator<String []> it = csvReader.iterator();
            while (it.hasNext()) {
                String [] songURL = it.next()[4].split("/");
                String id = songURL[songURL.length - 1];
                if (!"".equals(id)) idSet.add(id);
            }
        }
        String [] ids = idSet.toArray(new String [0]);
        HttpClient client = new DefaultHttpClient();
        Gson gson = new Gson();
        try (PrintWriter writer = new PrintWriter(new FileWriter("spotify.csv"))) {
            writer.println("URL,release-date,genres,danceability,energy,speechiness,valence,tempo");
            for (int i = 0; i < ids.length; i += LOOP_SIZE) {
                int retry = 3;
                while (retry > 0) {
                    try {
                        String requestIds = String.join(",", Arrays.copyOfRange(ids, i, i + LOOP_SIZE));
                        System.out.println(requestIds);
                        HttpGet getSongs = new HttpGet(GET_TRACKS + requestIds);
                        getSongs.addHeader("Authorization", "Bearer " + ACCESS_TOKEN);
                        LinkedTreeMap<String, Object> songsResponse = gson.fromJson(EntityUtils.toString(client.execute(getSongs).getEntity(), "UTF-8"), LinkedTreeMap.class);
                        List<LinkedTreeMap<String, Object>> tracks = (List) songsResponse.get("tracks");
                        String albumIds = tracks.stream().map(SpotiDump::albumIdFromTracks).collect(Collectors.joining(","));
                        HttpGet getAlbums = new HttpGet(GET_ALBUMS + albumIds);
                        getAlbums.addHeader("Authorization", "Bearer " + ACCESS_TOKEN);
                        LinkedTreeMap<String, Object> albumsResponse = gson.fromJson(EntityUtils.toString(client.execute(getAlbums).getEntity(), "UTF-8"), LinkedTreeMap.class);
                        List<LinkedTreeMap<String, Object>> albums = (List) albumsResponse.get("albums");
                        for (int j = i; j < i + LOOP_SIZE; j++) {
                            String id = ids[j];
                            System.out.println(id);
                            HttpGet getFeatures = new HttpGet(GET_FEATURES + id);
                            getFeatures.addHeader("Authorization", "Bearer " + ACCESS_TOKEN);
                            LinkedTreeMap<String, Object> featuresResponse = gson.fromJson(EntityUtils.toString(client.execute(getFeatures).getEntity(), "UTF-8"), LinkedTreeMap.class);
                            String danceability = featuresResponse.getOrDefault("danceability", "").toString();
                            String energy = featuresResponse.getOrDefault("energy", "").toString();
                            String speechiness = featuresResponse.getOrDefault("speechiness", "").toString();
                            String valence = featuresResponse.getOrDefault("valence", "").toString();
                            String tempo = featuresResponse.getOrDefault("tempo", "").toString();
                            writer.println(String.format("%s%s,%s,%s,%s,%s,%s,%s,%s",
                                    TRACK_URL, id, releaseDateFromAlbum(albums.get(j - i)), genresFromAlbum(albums.get(j - i)),
                                    danceability, energy, speechiness, valence, tempo));
                        }
                        break;
                    } catch (NullPointerException e) {
                        e.printStackTrace();
                        Thread.sleep(5000);
                        retry--;
                    }
                }
            }
        }
    }

    private static String albumIdFromTracks(LinkedTreeMap<String, Object> tracks) {
        return ((LinkedTreeMap<String, Object>) tracks.get("album")).get("id").toString();
    }

    private static String genresFromAlbum(LinkedTreeMap<String, Object> albums) {
        List<String> genres = ((List<String>) albums.get("genres"));
        if (genres.isEmpty()) return "";
        else return genres.get(0);
    }

    private static String releaseDateFromAlbum(LinkedTreeMap<String, Object> albums) {
        return albums.get("release_date").toString();
    }

}