Java tutorial
/* * Copyright (C) 2011 Erwin Betschart * * This file is part of Deshortener. * * 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/>. */ package ch.lipsch.deshortener; import java.io.IOException; import java.util.HashSet; import java.util.Set; import org.apache.http.Header; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.params.HttpClientParams; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.params.HttpParams; import android.net.Uri; import android.util.Log; /** * The Deshortener is responsible to resolve shortened url to the normal urls. * * @author Erwin Betschart */ public final class Deshortener { /** * Contains all the possible result states of a deshortening action. */ public enum ResultType { SUCCESS, NETWORK_ERROR, SHOWS_PREVIEW, CANNOT_DESHORTEN }; /** Contains all hosts which show a preview. */ private static final Set<String> PREVIEW_HOSTS = new HashSet<String>(); private static final String LOG_TAG = Deshortener.class.getName(); static { fillPreviewHosts(); } /** * Deshortens the provided uri. * * @param uriToDeshorten * The uri to deshorten. * @return Returns the result of the deshorten process. The result is only * successful when the given uri returns an 30x. Then value of the * Location header is returned within the result. * @throws IllegalArgumentException * If the provided uri is invalid. */ public static Result deshorten(Uri uriToDeshorten) { // Checks if the url shortener shows a preview if (checkForPreview(uriToDeshorten)) { return new Result(ResultType.SHOWS_PREVIEW); } // Open the network connetion HttpGet get = new HttpGet(uriToDeshorten.toString()); DefaultHttpClient client = new DefaultHttpClient(); HttpParams clientParams = client.getParams(); HttpClientParams.setRedirecting(clientParams, false); HttpResponse response = null; try { response = client.execute(get); } catch (ClientProtocolException e) { Log.e(LOG_TAG, "Unable to communicate to shortened url: " + uriToDeshorten.toString(), e); return new Result(ResultType.NETWORK_ERROR); } catch (IOException e) { Log.e(LOG_TAG, "Unable to communicate to shortened url: " + uriToDeshorten.toString(), e); return new Result(ResultType.NETWORK_ERROR); } // Check for redirection boolean isRedirection = ((response.getStatusLine().getStatusCode() == HttpStatus.SC_MOVED_PERMANENTLY) || (response.getStatusLine().getStatusCode() == HttpStatus.SC_MOVED_TEMPORARILY) || (response.getStatusLine().getStatusCode() == HttpStatus.SC_SEE_OTHER)); if (response != null && isRedirection) { Header header = response.getFirstHeader("Location"); String redirectValue = header.getValue(); Uri deshortenedUri = Uri.parse(redirectValue); return new Result(deshortenedUri); } else { return new Result(ResultType.CANNOT_DESHORTEN); } } private static void fillPreviewHosts() { PREVIEW_HOSTS.add("cli.gs"); } private static boolean checkForPreview(Uri uri) { return PREVIEW_HOSTS.contains(uri.getHost()); } /** * The result of a deshortening action. */ public final static class Result { private final ResultType resultType; private final Uri uri; /** * Creates a successful result. * * @param deshortenedUri * The successful deshortened uri. * @throws NullPointerException * Is thrown in case deshortenedUri is <code>null.</code> */ public Result(Uri deshortenedUri) { if (deshortenedUri == null) { throw new NullPointerException("deshortenedUri must not be null"); } uri = deshortenedUri; resultType = ResultType.SUCCESS; } /** * Creates an unsuccessful result. * * @param unsuccessfulReason * The failure reason. * @throws IllegalArgumentException * In case the provided reason was successful. */ public Result(ResultType unsuccessfulReason) { uri = null; resultType = unsuccessfulReason; if (wasSuccessful()) { throw new IllegalArgumentException("unsuccessfulReason must not be " + ResultType.SUCCESS); } } /** * Delivers the type of this result object. Provides information about * the type of error that occurred during the deshortening action. * * @return The type of result. */ public ResultType getResultType() { return resultType; } /** * Determines if the deshortening action was successfull or not. * * @return <code>true</code> if the deshortening action was successful * else <code>false</code>. */ public boolean wasSuccessful() { return ResultType.SUCCESS.equals(resultType); } /** * Delivers the deshortened uri. * * @return The deshortened uri. * @throws IllegalStateException * Must not be called in case of an unsuccessful result that * is {@linkplain Result#wasSuccessful()} returns * <code>false</code>. */ public Uri getDeshortenedUri() { if (!wasSuccessful()) { throw new IllegalStateException( "Cannot deliver deshortened uri. Result must be of type " + ResultType.SUCCESS); } return uri; } @Override public String toString() { StringBuilder stringRep = new StringBuilder("Deshortened result: ["); stringRep.append(resultType.toString()).append("]"); if (wasSuccessful()) { stringRep.append("; URL: ").append(getDeshortenedUri().toString()); } return stringRep.toString(); } } }