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This project contains some of the configurable modules used within the
Heritrix application to crawl the web. The modules in this project can
be used in applications other than Heritrix, however.
/*
* This file is part of the Heritrix web crawler (crawler.archive.org).
*
* Licensed to the Internet Archive (IA) by one or more individual
* contributors.
*
* The IA 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.archive.modules.extractor;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.commons.httpclient.URIException;
import org.apache.commons.lang.StringEscapeUtils;
import org.archive.io.ReplayCharSequence;
import org.archive.modules.CrawlURI;
import org.archive.util.TextUtils;
import org.archive.util.UriUtils;
/**
* A simple extractor which finds HTTP URIs inside XML/RSS files,
* inside attribute values and simple elements (those with only
* whitespace + HTTP URI + whitespace as contents).
*
* NOTE: This processor may open a ReplayCharSequence from the
* CrawlURI's Recorder, without closing that ReplayCharSequence, to allow
* reuse by later processors in sequence. In the usual (Heritrix) case, a
* call after all processing to the Recorder's endReplays() method ensures
* timely close of any reused ReplayCharSequences. Reuse of this processor
* elsewhere should ensure a similar cleanup call to Recorder.endReplays()
* occurs.
*
* @author gojomo
*/
public class ExtractorXML extends ContentExtractor {
@SuppressWarnings("unused")
private static final long serialVersionUID = 3L;
private static Logger logger =
Logger.getLogger(ExtractorXML.class.getName());
static final Pattern XML_URI_EXTRACTOR = Pattern
.compile("(?s)[\"\'>]\\s*(?:\\s\'\"@]+)\\s*(?:\\]\\]>)?[\"\'<]");
// GROUPS:
// (G1) possible uri
public ExtractorXML() {
}
@Override
protected boolean shouldExtract(CrawlURI curi) {
String mimeType = curi.getContentType();
// first check for xml mimetype or file extension
// application/vnd.openxmlformats.* seem to be zip archives
if (mimeType != null
&& (mimeType.toLowerCase().indexOf("xml") >= 0 && !mimeType
.matches("(?i)application/vnd.openxmlformats.*"))
|| curi.toString().toLowerCase().endsWith(".rss")
|| curi.toString().toLowerCase().endsWith(".xml")) {
return true;
}
// check if content starts with xml preamble "\\s]).*")) {
return true;
}
return false;
}
/**
* @param curi Crawl URI to process.
*/
@Override
protected boolean innerExtract(CrawlURI curi) {
ReplayCharSequence cs = null;
Charset contentDeclaredEncoding = null;
try {
// if charset not spec'd in http header look for
if (!curi.containsContentTypeCharsetDeclaration()) {
String contentPrefix = curi.getRecorder().getContentReplayPrefixString(50);
contentDeclaredEncoding = getContentDeclaredCharset(curi, contentPrefix);
if(!curi.getRecorder().getCharset().equals(contentDeclaredEncoding) && contentDeclaredEncoding!=null) {
String newContentPrefix = curi.getRecorder().getContentReplayPrefixString(50,contentDeclaredEncoding);
Charset reflexiveCharset = getContentDeclaredCharset(curi, newContentPrefix);
if(contentDeclaredEncoding.equals(reflexiveCharset)) {
// content-declared charset is self-consistent; use
curi.getAnnotations().add("usingCharsetInXML:"+contentDeclaredEncoding);
curi.getRecorder().setCharset(contentDeclaredEncoding);
} else {
// error: declared charset not evident once put into effect
curi.getAnnotations().add("inconsistentCharsetInXML:"+contentDeclaredEncoding);
// so, ignore in favor of original default
}
}
}
cs = curi.getRecorder().getContentReplayCharSequence();
numberOfLinksExtracted.addAndGet(processXml(this, curi, cs));
// Set flag to indicate that link extraction is completed.
return true;
} catch (IOException e) {
logger.severe("Failed getting ReplayCharSequence: " + e.getMessage());
}
return false;
}
protected Charset getContentDeclaredCharset(CrawlURI curi, String contentPrefix) {
Matcher m = TextUtils.getMatcher("(?s)<\\?xml\\s+[^>]*encoding=['\"]([^'\"]+)['\"]", contentPrefix);
String charsetName = null;
try {
if(m.find()) {
charsetName = m.group(1);
return Charset.forName(charsetName);
}
} catch (IllegalArgumentException iae) {
logger.log(Level.INFO,"Unknown content-encoding '"+charsetName+"' declared; using default");
curi.getAnnotations().add("unsatisfiableCharsetInXML:"+charsetName);
} finally {
TextUtils.recycleMatcher(m);
}
return null;
}
public static long processXml(Extractor ext,
CrawlURI curi, CharSequence cs) {
long foundLinks = 0;
Matcher matcher = XML_URI_EXTRACTOR.matcher(cs);
while (matcher.find()) {
String xmlUri = StringEscapeUtils.unescapeXml(matcher.group(1));
if (UriUtils.isVeryLikelyUri(xmlUri)) {
foundLinks++;
try {
// treat as speculative, as whether context really
// intends to create a followable/fetchable URI is
// unknown
int max = ext.getExtractorParameters().getMaxOutlinks();
addRelativeToBase(curi, max, xmlUri,
LinkContext.SPECULATIVE_MISC, Hop.SPECULATIVE);
} catch (URIException e) {
// There may not be a controller (e.g. If we're being run
// by the extractor tool).
ext.logUriError(e, curi.getUURI(), xmlUri);
}
}
}
return foundLinks;
}
}