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GNU General Public License
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/* * Copyright (c) 2012, the Last.fm Java Project and Committers All rights * reserved. Redistribution and use of this software in source and binary forms, * with or without modification, are permitted provided that the following * conditions are met: - Redistributions of source code must retain the above * copyright notice, this list of conditions and the following disclaimer. - * Redistributions in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. THIS SOFTWARE IS * PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO * EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. *///ww w. j a va 2 s .c o m package com.paperairplane.music.share.utils.lastfm; import static com.paperairplane.music.share.utils.lastfm.StringUtilities.encode; import static com.paperairplane.music.share.utils.lastfm.StringUtilities.map; import android.content.Context; import com.paperairplane.music.share.utils.lastfm.Result.Status; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import java.io.BufferedWriter; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.net.HttpURLConnection; import java.net.Proxy; import java.net.URL; import java.util.Iterator; import java.util.Map; import java.util.Map.Entry; import java.util.WeakHashMap; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; /** * The <code>Caller</code> class handles the low-level communication between the * client and last.fm.<br/> * Direct usage of this class should be unnecessary since all method calls are * available via the methods in the <code>Artist</code>, <code>Album</code>, * <code>User</code>, etc. classes. If specialized calls which are not covered * by the Java API are necessary this class may be used directly.<br/> * Supports the setting of a custom {@link Proxy} and a custom * <code>User-Agent</code> HTTP header. * * @author Janni Kovacs */ public class Caller { private final static String PARAM_API_KEY = "api_key"; private final static String DEFAULT_API_ROOT = "http://ws.audioscrobbler.com/2.0/"; private static Caller mInstance = null; private final String apiRootUrl = DEFAULT_API_ROOT; private final String userAgent = "Apollo"; private Result lastResult; /** * @param context The {@link Context} to use */ private Caller(final Context context) { } /** * @param context The {@link Context} to use * @return A new instance of this class */ public final static synchronized Caller getInstance(final Context context) { if (mInstance == null) { mInstance = new Caller(context.getApplicationContext()); } return mInstance; } /** * @param method * @param apiKey * @param params * @return * @throws CallException */ public Result call(final String method, final String apiKey, final String... params) { return call(method, apiKey, map(params)); } /** * Performs the web-service call. If the <code>session</code> parameter is * <code>non-null</code> then an authenticated call is made. If it's * <code>null</code> then an unauthenticated call is made.<br/> * The <code>apiKey</code> parameter is always required, even when a valid * session is passed to this method. * * @param method The method to call * @param apiKey A Last.fm API key * @param params Parameters * @param session A Session instance or <code>null</code> * @return the result of the operation */ public Result call(final String method, final String apiKey, Map<String, String> params) { params = new WeakHashMap<String, String>(params); InputStream inputStream = null; // no entry in cache, load from web if (inputStream == null) { // fill parameter map with apiKey and session info params.put(PARAM_API_KEY, apiKey); try { final HttpURLConnection urlConnection = openPostConnection(method, params); inputStream = getInputStreamFromConnection(urlConnection); if (inputStream == null) { lastResult = Result.createHttpErrorResult(urlConnection.getResponseCode(), urlConnection.getResponseMessage()); return lastResult; } } catch (final IOException ignored) { } } try { final Result result = createResultFromInputStream(inputStream); lastResult = result; return result; } catch (final IOException ignored) { } catch (final SAXException ignored) { } return null; } /** * Creates a new {@link HttpURLConnection}, sets the proxy, if available, * and sets the User-Agent property. * * @param url URL to connect to * @return a new connection. * @throws IOException if an I/O exception occurs. */ public HttpURLConnection openConnection(final String url) throws IOException { final URL u = new URL(url); HttpURLConnection urlConnection; urlConnection = (HttpURLConnection)u.openConnection(); urlConnection.setRequestProperty("User-Agent", userAgent); urlConnection.setUseCaches(true); return urlConnection; } /** * @param method * @param params * @return * @throws IOException */ private HttpURLConnection openPostConnection(final String method, final Map<String, String> params) throws IOException { final HttpURLConnection urlConnection = openConnection(apiRootUrl); urlConnection.setRequestMethod("POST"); urlConnection.setDoOutput(true); urlConnection.setUseCaches(true); final OutputStream outputStream = urlConnection.getOutputStream(); final BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream)); final String post = buildPostBody(method, params); writer.write(post); writer.close(); return urlConnection; } /** * @param connection * @return * @throws IOException */ private InputStream getInputStreamFromConnection(final HttpURLConnection connection) throws IOException { final int responseCode = connection.getResponseCode(); if (responseCode == HttpURLConnection.HTTP_FORBIDDEN || responseCode == HttpURLConnection.HTTP_BAD_REQUEST) { return connection.getErrorStream(); } else if (responseCode == HttpURLConnection.HTTP_OK) { return connection.getInputStream(); } return null; } /** * @param inputStream * @return * @throws SAXException * @throws IOException */ private Result createResultFromInputStream(final InputStream inputStream) throws SAXException, IOException { final Document document = newDocumentBuilder().parse( new InputSource(new InputStreamReader(inputStream, "UTF-8"))); final Element root = document.getDocumentElement(); // lfm element final String statusString = root.getAttribute("status"); final Status status = "ok".equals(statusString) ? Status.OK : Status.FAILED; if (status == Status.FAILED) { final Element errorElement = (Element)root.getElementsByTagName("error").item(0); final int errorCode = Integer.parseInt(errorElement.getAttribute("code")); final String message = errorElement.getTextContent(); return Result.createRestErrorResult(errorCode, message); } else { return Result.createOkResult(document); } } /** * @return */ private DocumentBuilder newDocumentBuilder() { try { final DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance(); return builderFactory.newDocumentBuilder(); } catch (final ParserConfigurationException e) { // better never happens throw new RuntimeException(e); } } /** * @param method * @param params * @param strings * @return */ private String buildPostBody(final String method, final Map<String, String> params, final String... strings) { final StringBuilder builder = new StringBuilder(100); builder.append("method="); builder.append(method); builder.append('&'); for (final Iterator<Entry<String, String>> it = params.entrySet().iterator(); it.hasNext();) { final Entry<String, String> entry = it.next(); builder.append(entry.getKey()); builder.append('='); builder.append(encode(entry.getValue())); if (it.hasNext() || strings.length > 0) { builder.append('&'); } } int count = 0; for (final String string : strings) { builder.append(count % 2 == 0 ? string : encode(string)); count++; if (count != strings.length) { if (count % 2 == 0) { builder.append('&'); } else { builder.append('='); } } } return builder.toString(); } }