org.apache.tika.parser.html.HtmlParser Maven / Gradle / Ivy
/*
* 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.parser.html;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.tika.exception.TikaException;
import org.apache.tika.io.CloseShieldInputStream;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.mime.MediaType;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.Parser;
import org.apache.tika.parser.txt.CharsetDetector;
import org.apache.tika.parser.txt.CharsetMatch;
import org.apache.tika.utils.CharsetUtils;
import org.ccil.cowan.tagsoup.HTMLSchema;
import org.ccil.cowan.tagsoup.Schema;
import org.xml.sax.ContentHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
/**
* HTML parser. Uses TagSoup to turn the input document to HTML SAX events,
* and post-processes the events to produce XHTML and metadata expected by
* Tika clients.
*/
public class HtmlParser implements Parser {
private static final Set SUPPORTED_TYPES =
Collections.unmodifiableSet(new HashSet(Arrays.asList(
MediaType.text("html"),
MediaType.application("xhtml+xml"),
MediaType.application("vnd.wap.xhtml+xml"),
MediaType.application("x-asp"))));
// Use the widest, most common charset as our default.
private static final String DEFAULT_CHARSET = "windows-1252";
// TIKA-357 - use bigger buffer for meta tag sniffing (was 4K)
private static final int META_TAG_BUFFER_SIZE = 8192;
private static final Pattern HTTP_EQUIV_PATTERN = Pattern.compile(
"(?is) getSupportedTypes(ParseContext context) {
return SUPPORTED_TYPES;
}
/**
* TIKA-332: Check for meta http-equiv tag with charset info in
* HTML content.
*
* TODO: Move this into core, along with CharsetDetector
*/
private String getEncoding(InputStream stream, Metadata metadata) throws IOException {
stream.mark(META_TAG_BUFFER_SIZE);
char[] buffer = new char[META_TAG_BUFFER_SIZE];
InputStreamReader isr = new InputStreamReader(stream, "us-ascii");
int bufferSize = isr.read(buffer);
stream.reset();
if (bufferSize != -1) {
String metaString = new String(buffer, 0, bufferSize);
Matcher m = HTTP_EQUIV_PATTERN.matcher(metaString);
if (m.find()) {
// TIKA-349: flexible handling of attributes
// We have one or more x or x=y attributes, separated by ';'
String[] attrs = m.group(1).split(";");
for (String attr : attrs) {
String[] keyValue = attr.trim().split("=");
if ((keyValue.length == 2) && keyValue[0].equalsIgnoreCase("charset")) {
// TIKA-459: improve charset handling.
String charset = CharsetUtils.clean(keyValue[1]);
if (CharsetUtils.isSupported(charset)) {
metadata.set(Metadata.CONTENT_ENCODING, charset);
return charset;
}
}
}
}
}
// No (valid) charset in a meta http-equiv tag, see if it's in the passed content-encoding
// hint, or the passed content-type hint.
CharsetDetector detector = new CharsetDetector();
String incomingCharset = metadata.get(Metadata.CONTENT_ENCODING);
String incomingType = metadata.get(Metadata.CONTENT_TYPE);
if (incomingCharset == null && incomingType != null) {
// TIKA-341: Use charset in content-type
MediaType mt = MediaType.parse(incomingType);
if (mt != null) {
String charset = mt.getParameters().get("charset");
if ((charset != null) && Charset.isSupported(charset)) {
incomingCharset = charset;
}
}
}
if (incomingCharset != null) {
detector.setDeclaredEncoding(incomingCharset);
}
// TIKA-341 without enabling input filtering (stripping of tags) the
// short HTML tests don't work well.
detector.enableInputFilter(true);
detector.setText(stream);
for (CharsetMatch match : detector.detectAll()) {
if (Charset.isSupported(match.getName())) {
metadata.set(Metadata.CONTENT_ENCODING, match.getName());
// TIKA-339: Don't set language, as it's typically not a very good
// guess, and it can create ambiguity if another (better) language
// value is specified by a meta tag in the HTML (or via HTTP response
// header).
/*
String language = match.getLanguage();
if (language != null) {
metadata.set(Metadata.CONTENT_LANGUAGE, match.getLanguage());
metadata.set(Metadata.LANGUAGE, match.getLanguage());
}
*/
break;
}
}
String encoding = metadata.get(Metadata.CONTENT_ENCODING);
if (encoding == null) {
if (Charset.isSupported(DEFAULT_CHARSET)) {
encoding = DEFAULT_CHARSET;
} else {
encoding = Charset.defaultCharset().name();
}
metadata.set(Metadata.CONTENT_ENCODING, encoding);
}
return encoding;
}
public void parse(
InputStream stream, ContentHandler handler,
Metadata metadata, ParseContext context)
throws IOException, SAXException, TikaException {
// The getEncoding() method depends on the mark feature
if (!stream.markSupported()) {
stream = new BufferedInputStream(stream);
}
// Protect the stream from being closed by CyberNeko
// TODO: Is this still needed, given our use of TagSoup?
stream = new CloseShieldInputStream(stream);
// Prepare the input source using the encoding hint if available
InputSource source = new InputSource(stream);
source.setEncoding(getEncoding(stream, metadata));
// Get the HTML mapper from the parse context
HtmlMapper mapper =
context.get(HtmlMapper.class, new HtmlParserMapper());
// Parse the HTML document
org.ccil.cowan.tagsoup.Parser parser =
new org.ccil.cowan.tagsoup.Parser();
// Instantiating HTMLSchema is heavy, therefore reuse a cached instance
parser.setProperty(org.ccil.cowan.tagsoup.Parser.schemaProperty, HTML_SCHEMA);
parser.setContentHandler(new XHTMLDowngradeHandler(
new HtmlHandler(mapper, handler, metadata)));
parser.parse(source);
}
/**
* @deprecated This method will be removed in Apache Tika 1.0.
*/
public void parse(
InputStream stream, ContentHandler handler, Metadata metadata)
throws IOException, SAXException, TikaException {
parse(stream, handler, metadata, new ParseContext());
}
/**
* Maps "safe" HTML element names to semantic XHTML equivalents. If the
* given element is unknown or deemed unsafe for inclusion in the parse
* output, then this method returns null and the element
* will be ignored but the content inside it is still processed. See
* the {@link #isDiscardElement(String)} method for a way to discard
* the entire contents of an element.
*
* Subclasses can override this method to customize the default mapping.
*
* @deprecated Use the {@link HtmlMapper} mechanism to customize
* the HTML mapping. This method will be removed in Tika 1.0.
* @since Apache Tika 0.5
* @param name HTML element name (upper case)
* @return XHTML element name (lower case), or
* null if the element is unsafe
*/
protected String mapSafeElement(String name) {
return DefaultHtmlMapper.INSTANCE.mapSafeElement(name);
}
/**
* Checks whether all content within the given HTML element should be
* discarded instead of including it in the parse output. Subclasses
* can override this method to customize the set of discarded elements.
*
* @deprecated Use the {@link HtmlMapper} mechanism to customize
* the HTML mapping. This method will be removed in Tika 1.0.
* @since Apache Tika 0.5
* @param name HTML element name (upper case)
* @return true if content inside the named element
* should be ignored, false otherwise
*/
protected boolean isDiscardElement(String name) {
return DefaultHtmlMapper.INSTANCE.isDiscardElement(name);
}
/**
* @deprecated Use the {@link HtmlMapper} mechanism to customize
* the HTML mapping. This method will be removed in Tika 1.0.
**/
public String mapSafeAttribute(String elementName, String attributeName) {
return DefaultHtmlMapper.INSTANCE.mapSafeAttribute(elementName,attributeName) ;
}
/**
* Adapter class that maintains backwards compatibility with the
* protected HtmlParser methods. Making HtmlParser implement HtmlMapper
* directly would require those methods to be public, which would break
* backwards compatibility with subclasses.
*
* @deprecated Use the {@link HtmlMapper} mechanism to customize
* the HTML mapping. This class will be removed in Tika 1.0.
*/
private class HtmlParserMapper implements HtmlMapper {
public String mapSafeElement(String name) {
return HtmlParser.this.mapSafeElement(name);
}
public boolean isDiscardElement(String name) {
return HtmlParser.this.isDiscardElement(name);
}
public String mapSafeAttribute(String elementName, String attributeName){
return HtmlParser.this.mapSafeAttribute(elementName,attributeName);
}
}
}