Pierre De Rop | 6e8f921 | 2016-02-20 21:44:59 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one |
| 3 | * or more contributor license agreements. See the NOTICE file |
| 4 | * distributed with this work for additional information |
| 5 | * regarding copyright ownership. The ASF licenses this file |
| 6 | * to you under the Apache License, Version 2.0 (the |
| 7 | * "License"); you may not use this file except in compliance |
| 8 | * with the License. You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, |
| 13 | * software distributed under the License is distributed on an |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 15 | * KIND, either express or implied. See the License for the |
| 16 | * specific language governing permissions and limitations |
| 17 | * under the License. |
| 18 | */ |
Pierre De Rop | faca289 | 2016-01-31 23:27:05 +0000 | [diff] [blame] | 19 | package org.apache.felix.dm.lambda.samples.future; |
| 20 | |
| 21 | import static org.apache.felix.dm.lambda.DependencyManagerActivator.component; |
| 22 | |
| 23 | import java.io.IOException; |
| 24 | import java.net.URL; |
| 25 | import java.util.ArrayList; |
| 26 | import java.util.List; |
| 27 | import java.util.Scanner; |
| 28 | import java.util.concurrent.CompletableFuture; |
| 29 | import java.util.regex.Matcher; |
| 30 | import java.util.regex.Pattern; |
| 31 | |
| 32 | import org.apache.felix.dm.Component; |
| 33 | import org.osgi.service.log.LogService; |
| 34 | |
| 35 | /** |
| 36 | * Provides all hrefs found from a given web page. |
| 37 | */ |
| 38 | public class PageLinksImpl implements PageLinks { |
| 39 | private LogService m_log; |
| 40 | private final static String HREF_PATTERN = "<a\\s+href\\s*=\\s*(\"[^\"]*\"|[^\\s>]*)\\s*>"; |
| 41 | private List<String> m_links; // web page hrefs (links). |
| 42 | private String m_url; |
| 43 | |
| 44 | PageLinksImpl(String url) { |
| 45 | m_url = url; |
| 46 | } |
| 47 | |
| 48 | void bind(LogService log) { |
| 49 | m_log = log; |
| 50 | } |
| 51 | |
| 52 | void init(Component c) { |
| 53 | // asynchronously download the content of the URL specified in the constructor. |
| 54 | CompletableFuture<List<String>> futureLinks = CompletableFuture.supplyAsync(() -> download(m_url)) |
| 55 | .thenApply(this::parseLinks); |
| 56 | |
| 57 | // Add the future dependency so we'll be started once the CompletableFuture "futureLinks" has completed. |
Pierre De Rop | 1152750 | 2016-02-18 21:07:16 +0000 | [diff] [blame] | 58 | component(c, comp -> comp.withFuture(futureLinks, future -> future.complete(this::setLinks))); |
Pierre De Rop | faca289 | 2016-01-31 23:27:05 +0000 | [diff] [blame] | 59 | } |
| 60 | |
| 61 | // Called when our future has completed. |
| 62 | void setLinks(List<String> links) { |
| 63 | m_links = links; |
| 64 | } |
| 65 | |
| 66 | // once our future has completed, our component is started. |
| 67 | void start() { |
Pierre De Rop | 1152750 | 2016-02-18 21:07:16 +0000 | [diff] [blame] | 68 | m_log.log(LogService.LOG_WARNING, "Service starting: number of links found from Felix web site: " + m_links.size()); |
Pierre De Rop | faca289 | 2016-01-31 23:27:05 +0000 | [diff] [blame] | 69 | } |
| 70 | |
| 71 | @Override |
| 72 | public List<String> getLinks() { |
| 73 | return m_links; |
| 74 | } |
| 75 | |
| 76 | private String download(String url) { |
| 77 | try (Scanner in = new Scanner(new URL(url).openStream())) { |
| 78 | StringBuilder builder = new StringBuilder(); |
| 79 | while (in.hasNextLine()) { |
| 80 | builder.append(in.nextLine()); |
| 81 | builder.append("\n"); |
| 82 | } |
| 83 | return builder.toString(); |
| 84 | } catch (IOException ex) { |
| 85 | RuntimeException rex = new RuntimeException(); |
| 86 | rex.initCause(ex); |
| 87 | throw rex; |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | private List<String> parseLinks(String content) { |
| 92 | Pattern pattern = Pattern.compile(HREF_PATTERN, Pattern.CASE_INSENSITIVE); |
| 93 | Matcher matcher = pattern.matcher(content); |
| 94 | List<String> result = new ArrayList<>(); |
| 95 | while (matcher.find()) |
| 96 | result.add(matcher.group(1)); |
| 97 | return result; |
| 98 | } |
| 99 | } |