| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.felix.dm.lambda.samples.future; |
| |
| import static org.apache.felix.dm.lambda.DependencyManagerActivator.component; |
| |
| import java.io.IOException; |
| import java.net.URL; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Scanner; |
| import java.util.concurrent.CompletableFuture; |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| |
| import org.apache.felix.dm.Component; |
| import org.osgi.service.log.LogService; |
| |
| /** |
| * Provides all hrefs found from a given web page. |
| */ |
| public class PageLinksImpl implements PageLinks { |
| private LogService m_log; |
| private final static String HREF_PATTERN = "<a\\s+href\\s*=\\s*(\"[^\"]*\"|[^\\s>]*)\\s*>"; |
| private List<String> m_links; // web page hrefs (links). |
| private String m_url; |
| |
| PageLinksImpl(String url) { |
| m_url = url; |
| } |
| |
| void bind(LogService log) { |
| m_log = log; |
| } |
| |
| void init(Component c) { |
| // asynchronously download the content of the URL specified in the constructor. |
| CompletableFuture<List<String>> futureLinks = CompletableFuture.supplyAsync(() -> download(m_url)) |
| .thenApply(this::parseLinks); |
| |
| // Add the future dependency so we'll be started once the CompletableFuture "futureLinks" has completed. |
| component(c, comp -> comp.withFuture(futureLinks, future -> future.complete(this::setLinks))); |
| } |
| |
| // Called when our future has completed. |
| void setLinks(List<String> links) { |
| m_links = links; |
| } |
| |
| // once our future has completed, our component is started. |
| void start() { |
| m_log.log(LogService.LOG_WARNING, "Service starting: number of links found from Felix web site: " + m_links.size()); |
| } |
| |
| @Override |
| public List<String> getLinks() { |
| return m_links; |
| } |
| |
| private String download(String url) { |
| try (Scanner in = new Scanner(new URL(url).openStream())) { |
| StringBuilder builder = new StringBuilder(); |
| while (in.hasNextLine()) { |
| builder.append(in.nextLine()); |
| builder.append("\n"); |
| } |
| return builder.toString(); |
| } catch (IOException ex) { |
| RuntimeException rex = new RuntimeException(); |
| rex.initCause(ex); |
| throw rex; |
| } |
| } |
| |
| private List<String> parseLinks(String content) { |
| Pattern pattern = Pattern.compile(HREF_PATTERN, Pattern.CASE_INSENSITIVE); |
| Matcher matcher = pattern.matcher(content); |
| List<String> result = new ArrayList<>(); |
| while (matcher.find()) |
| result.add(matcher.group(1)); |
| return result; |
| } |
| } |