LyricsService.java

/*
 This file is part of Subsonic.

 Subsonic 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.

 Subsonic 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 Subsonic.  If not, see <http://www.gnu.org/licenses/>.

 Copyright 2009 (C) Sindre Mehus
 */
package net.sourceforge.subsonic.ajax;

import net.sourceforge.subsonic.Logger;
import net.sourceforge.subsonic.util.StringUtil;

import org.apache.http.client.HttpClient;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.client.BasicResponseHandler;
import org.apache.http.params.HttpConnectionParams;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.Namespace;
import org.jdom.input.SAXBuilder;

import java.io.IOException;
import java.io.StringReader;

/**
 * Provides AJAX-enabled services for retrieving song lyrics from chartlyrics.com.
 * <p/>
 * See http://www.chartlyrics.com/api.aspx for details.
 * <p/>
 * This class is used by the DWR framework (http://getahead.ltd.uk/dwr/).
 *
 * @author Sindre Mehus
 */
public class LyricsService {

    private static final Logger LOG = Logger.getLogger(LyricsService.class);

    /**
     * Returns lyrics for the given song and artist.
     *
     * @param artist The artist.
     * @param song   The song.
     * @return The lyrics, never <code>null</code> .
     */
    public LyricsInfo getLyrics(String artist, String song) {
        try {

            artist = StringUtil.urlEncode(artist);
            song = StringUtil.urlEncode(song);

            String url = "http://api.chartlyrics.com/apiv1.asmx/SearchLyric?artist=" + artist + "&song=" + song;
            String xml = executeGetRequest(url);

            SearchLyricResult searchResult = parseSearchLyric(xml);
            if (searchResult == null) {
                return new LyricsInfo();
            }

            // Wait a little while, otherwise chartlyrics refuses the request
            Thread.sleep(1000);

            url = "http://api.chartlyrics.com/apiv1.asmx/GetLyric?lyricId=" + searchResult.getId() + "&lyricCheckSum=" + searchResult.getChecksum();
            xml = executeGetRequest(url);
            return parseSearchResult(xml);

        } catch (Exception x) {
            LOG.warn("Failed to get lyrics for song '" + song + "'.", x);
            return new LyricsInfo();
        }
    }

    private SearchLyricResult parseSearchLyric(String xml) throws Exception {
        SAXBuilder builder = new SAXBuilder();
        Document document = builder.build(new StringReader(xml));

        Element root = document.getRootElement();
        Namespace ns = root.getNamespace();
        Element element = root.getChild("SearchLyricResult", ns);
        if (element == null) {
            return null;
        }

        String id = element.getChildText("LyricId", ns);
        String checksum = element.getChildText("LyricChecksum", ns);

        if (id == null || checksum == null) {
            return null;
        }

        return new SearchLyricResult(id, checksum);
    }

    private LyricsInfo parseSearchResult(String xml) throws Exception {
        SAXBuilder builder = new SAXBuilder();
        Document document = builder.build(new StringReader(xml));

        Element root = document.getRootElement();
        Namespace ns = root.getNamespace();

        String lyric = root.getChildText("Lyric", ns);
        String song =  root.getChildText("LyricSong", ns);
        String artist =  root.getChildText("LyricArtist", ns);

        return new LyricsInfo(lyric, artist, song);
    }

    private String executeGetRequest(String url) throws IOException {
        HttpClient client = new DefaultHttpClient();
        HttpConnectionParams.setConnectionTimeout(client.getParams(), 15000);
        HttpConnectionParams.setSoTimeout(client.getParams(), 15000);
        HttpGet method = new HttpGet(url);
        try {

            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            return client.execute(method, responseHandler);

        } finally {
            client.getConnectionManager().shutdown();
        }
    }

    private static class SearchLyricResult {

        private final String id;
        private final String checksum;

        private SearchLyricResult(String id, String checksum) {
            this.id = id;
            this.checksum = checksum;
        }

        public String getId() {
            return id;
        }

        public String getChecksum() {
            return checksum;
        }
    }
}