/*
* 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.tika.utils;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Inspired from Nutch code class OutlinkExtractor. Apply regex to extract
* content
*
*
*/
public class RegexUtils {
/**
* Regex pattern to get URLs within a plain text.
*
* @see <a
* href="http://www.truerwords.net/articles/ut/urlactivation.html">http://www.truerwords.net/articles/ut/urlactivation.html
* </a>
*/
private static final String LINKS_REGEX =
"([A-Za-z][A-Za-z0-9+.-]{1,120}:"
+ "[A-Za-z0-9/](([A-Za-z0-9$_.+!*,;/?:@&~=-])|%[A-Fa-f0-9]{2}){1,333}"
+ "(#([a-zA-Z0-9][a-zA-Z0-9$_.+!*,;/?:@&~=%-]{0,1000}))?)";
private static final Pattern LINKS_PATTERN = Pattern.compile(LINKS_REGEX, Pattern.CASE_INSENSITIVE + Pattern.MULTILINE);
/**
* Extract urls from plain text.
*
* @param content The plain text content to examine
* @return List of urls within found in the plain text
*/
public static List<String> extractLinks(String content) {
if (content == null || content.length() == 0) {
return Collections.emptyList();
}
List<String> extractions = new ArrayList<String>();
final Matcher matcher = LINKS_PATTERN.matcher(content);
while (matcher.find()) {
extractions.add(matcher.group());
}
return extractions;
}
}