/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright (c) 2013-2015 Oracle and/or its affiliates. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can
* obtain a copy of the License at
* http://glassfish.java.net/public/CDDL+GPL_1_1.html
* or packager/legal/LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at packager/legal/LICENSE.txt.
*
* GPL Classpath Exception:
* Oracle designates this particular file as subject to the "Classpath"
* exception as provided by Oracle in the GPL Version 2 section of the License
* file that accompanied this code.
*
* Modifications:
* If applicable, add the following below the License Header, with the fields
* enclosed by brackets [] replaced by your own identifying information:
* "Portions Copyright [year] [name of copyright owner]"
*
* Contributor(s):
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
package org.glassfish.jersey.examples.shortener.webapp.service;
import java.net.URI;
import java.util.concurrent.ConcurrentMap;
import javax.ws.rs.core.UriBuilder;
import org.glassfish.jersey.examples.shortener.webapp.domain.ShortenedLink;
import org.glassfish.jersey.internal.util.collection.DataStructures;
/**
* Service responsible for shortening links and storing shortened links in memory.
*
* @author Michal Gajdos
*/
public final class ShortenerService {
private static final String ALPHABET = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
private static final int BASE = ALPHABET.length();
private static final ConcurrentMap<String, ShortenedLink> store = DataStructures.createConcurrentMap();
public static ShortenedLink shortenLink(final URI baseUri, final String link) {
// Remove this condition if you want to create different shortened links for the same URI.
if (store.containsKey(encode(link))) {
return store.get(encode(link));
}
String path = link;
ShortenedLink shortenedLink;
do {
path = encode(path);
shortenedLink = new ShortenedLink(URI.create(link),
UriBuilder.fromUri(baseUri).path("i").path(path).build(),
UriBuilder.fromUri(baseUri).path("r").path(path).build());
} while (store.putIfAbsent(path, shortenedLink) != null);
return store.get(path);
}
public static ShortenedLink getLink(final String link) {
return store.get(link);
}
public static boolean containsLink(final ShortenedLink link) {
return store.containsValue(link);
}
/**
* Implementation details described at http://stackoverflow.com/a/742047/290799.
*/
private static String encode(final String link) {
final StringBuilder builder = new StringBuilder();
// NOTE: Math.abs(Integer.MIN_VALUE) = Integer.MIN_VALUE (negative value)
int hash = Math.abs(link.hashCode());
while (hash > 0 || hash == Integer.MIN_VALUE) {
builder.append(ALPHABET.charAt(Math.abs(hash % BASE)));
hash = Math.abs(hash / BASE);
}
return builder.reverse().toString();
}
}