volker.streaming.music.lastfm.LastFmApi.java Source code

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Here is the source code for volker.streaming.music.lastfm.LastFmApi.java

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package volker.streaming.music.lastfm;

/*
 * #%L
 * NowPlaying
 * %%
 * Copyright (C) 2013 Volker Lanting
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the 
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public 
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/gpl-3.0.html>.
 * #L%
 */

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Iterator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.Consts;
import org.apache.http.HttpMessage;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.config.ConnectionConfig;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;

import volker.streaming.music.Track;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Contains java calls for some of the LastFM API calls.
 * 
 * @author Volker Lanting
 */
public class LastFmApi {

    private static final Log LOG = LogFactory.getLog(LastFmApi.class);

    private final LastFmConfig config;

    public LastFmApi(LastFmConfig config) {
        this.config = config;
        LOG.info("Created API with config:" + config.toString());
    }

    public Track getNowPlaying() {
        Track result = null;

        // setup API url
        URI uri = null;
        try {
            uri = getApiUri().addParameter("method", "user.getrecenttracks").addParameter("user", config.getUser())
                    .addParameter("api_key", config.getApiKey()).addParameter("format", "json")
                    .addParameter("limit", "1").addParameter("extended", "0").build();
        } catch (URISyntaxException e) {
            LOG.fatal("Configuration error. Invalid API url.", e);
            return null;
        }

        // setup the request
        CloseableHttpClient client = getClient().build();
        HttpGet getRequest = new HttpGet(uri);
        setHeaders(getRequest);

        // execute the request
        CloseableHttpResponse response = null;
        try {
            response = client.execute(getRequest);
        } catch (IOException e) {
            LOG.fatal("Failed to execute request.", e);
            close(response, client);
            return null;
        }

        // read the response
        InputStream responseStream = null;
        JsonNode root = null;
        try {
            ObjectMapper mapper = new ObjectMapper();
            responseStream = response.getEntity().getContent();
            root = mapper.readTree(responseStream);
            LOG.info("Last FM API returned :" + root.toString());
        } catch (JsonProcessingException e1) {
            LOG.fatal("Returned JSON was invalid.", e1);
            close(response, client);
            return null;
        } catch (IOException e1) {
            LOG.fatal("Failed to read response stream.", e1);
            close(response, client);
            return null;
        } finally {
            close(responseStream);
        }

        if (root.hasNonNull("error")) {
            LOG.error("Error returned by API: " + (root.hasNonNull("message") ? root.get("message").asText() : ""));
        } else {
            JsonNode recentTracks = root.get("recenttracks");
            Iterator<JsonNode> tracks;
            if (recentTracks.hasNonNull("track")) {
                tracks = recentTracks.get("track").elements();
            } else {
                // no tracks ever listened to
                tracks = new ArrayList<JsonNode>().iterator();
            }
            if (tracks.hasNext()) {
                JsonNode mostRecent = tracks.next();
                if (mostRecent.hasNonNull("@attr")) {
                    JsonNode attr = mostRecent.get("@attr");
                    if (attr.hasNonNull("nowplaying") && attr.get("nowplaying").asBoolean()) {
                        // mostRecent is the currently playing track
                        try {
                            result = LastFmTrackFactory.fromJson(mostRecent);
                        } catch (IllegalArgumentException e) {
                            LOG.error("JSON response contained an invalid Track.", e);
                        }
                    }
                }
            }
        }

        // close stuff
        close(response, client);
        return result;
    }

    private static void close(Closeable... cs) {
        for (Closeable c : cs) {
            try {
                if (c != null)
                    c.close();
            } catch (IOException e) {
                LOG.error("Failed to properly close something.", e);
            }
        }
    }

    // -----------------------
    // Private helper methods
    // -----------------------

    /*
     * Returns a URIBuilder for the LastFM api. You just have to add any params.
     */
    private URIBuilder getApiUri() {
        return new URIBuilder().setScheme(config.getApiScheme()).setHost(config.getApiBase())
                .setPath(config.getApiPath());
    }

    // Get HttpClient with UTF8 Charset
    private static HttpClientBuilder getClient() {
        // use utf8 encoding as requested by Last FM
        ConnectionConfig conConfig = ConnectionConfig.custom().setCharset(Consts.UTF_8).build();
        return HttpClients.custom().setDefaultConnectionConfig(conConfig);
    }

    // sets some headers
    private static void setHeaders(HttpMessage message) {
        // Last FM requests setting a user agent
        // we can trust Apache to set the default
        // we expect json
        message.setHeader("Accept", "application/json");
    }
}