/*
* 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.sax;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
/**
* SAX event handler that serializes the XML document to a character stream.
* The incoming SAX events are expected to be well-formed (properly nested,
* etc.) and to explicitly include namespace declaration attributes and
* corresponding namespace prefixes in element and attribute names.
*
* @since Apache Tika 0.10
*/
public class ToXMLContentHandler extends ToTextContentHandler {
private static class ElementInfo {
private final ElementInfo parent;
private final Map<String, String> namespaces;
public ElementInfo(ElementInfo parent, Map<String, String> namespaces) {
this.parent = parent;
if (namespaces.isEmpty()) {
this.namespaces = Collections.emptyMap();
} else {
this.namespaces = new HashMap<String, String>(namespaces);
}
}
public String getPrefix(String uri) throws SAXException {
String prefix = namespaces.get(uri);
if (prefix != null) {
return prefix;
} else if (parent != null) {
return parent.getPrefix(uri);
} else if (uri == null || uri.length() == 0) {
return "";
} else {
throw new SAXException("Namespace " + uri + " not declared");
}
}
public String getQName(String uri, String localName)
throws SAXException {
String prefix = getPrefix(uri);
if (prefix.length() > 0) {
return prefix + ":" + localName;
} else {
return localName;
}
}
}
private final String encoding;
protected boolean inStartElement = false;
protected final Map<String, String> namespaces =
new HashMap<String, String>();
private ElementInfo currentElement;
/**
* Creates an XML serializer that writes to the given byte stream
* using the given character encoding.
*
* @param stream output stream
* @param encoding output encoding
* @throws UnsupportedEncodingException if the encoding is unsupported
*/
public ToXMLContentHandler(OutputStream stream, String encoding)
throws UnsupportedEncodingException {
super(stream, encoding);
this.encoding = encoding;
}
public ToXMLContentHandler(String encoding) {
super();
this.encoding = encoding;
}
public ToXMLContentHandler() {
super();
this.encoding = null;
}
/**
* Writes the XML prefix.
*/
@Override
public void startDocument() throws SAXException {
if (encoding != null) {
write("<?xml version=\"1.0\" encoding=\"");
write(encoding);
write("\"?>\n");
}
currentElement = null;
namespaces.clear();
}
@Override
public void startPrefixMapping(String prefix, String uri)
throws SAXException {
try {
if (currentElement != null
&& prefix.equals(currentElement.getPrefix(uri))) {
return;
}
} catch (SAXException ignore) {
}
namespaces.put(uri, prefix);
}
@Override
public void startElement(
String uri, String localName, String qName, Attributes atts)
throws SAXException {
lazyCloseStartElement();
currentElement = new ElementInfo(currentElement, namespaces);
write('<');
write(currentElement.getQName(uri, localName));
for (int i = 0; i < atts.getLength(); i++) {
write(' ');
write(currentElement.getQName(atts.getURI(i), atts.getLocalName(i)));
write('=');
write('"');
char[] ch = atts.getValue(i).toCharArray();
writeEscaped(ch, 0, ch.length, true);
write('"');
}
for (Map.Entry<String, String> entry : namespaces.entrySet()) {
write(' ');
write("xmlns");
String prefix = entry.getValue();
if (prefix.length() > 0) {
write(':');
write(prefix);
}
write('=');
write('"');
char[] ch = entry.getKey().toCharArray();
writeEscaped(ch, 0, ch.length, true);
write('"');
}
namespaces.clear();
inStartElement = true;
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if (inStartElement) {
write(" />");
inStartElement = false;
} else {
write("</");
write(qName);
write('>');
}
namespaces.clear();
// Reset the position in the tree, to avoid endless stack overflow
// chains (see TIKA-1070)
currentElement = currentElement.parent;
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
lazyCloseStartElement();
writeEscaped(ch, start, start + length, false);
}
private void lazyCloseStartElement() throws SAXException {
if (inStartElement) {
write('>');
inStartElement = false;
}
}
/**
* Writes the given character as-is.
*
* @param ch character to be written
* @throws SAXException if the character could not be written
*/
protected void write(char ch) throws SAXException {
super.characters(new char[] { ch }, 0, 1);
}
/**
* Writes the given string of character as-is.
*
* @param string string of character to be written
* @throws SAXException if the character string could not be written
*/
protected void write(String string) throws SAXException {
super.characters(string.toCharArray(), 0, string.length());
}
/**
* Writes the given characters as-is followed by the given entity.
*
* @param ch character array
* @param from start position in the array
* @param to end position in the array
* @param entity entity code
* @return next position in the array,
* after the characters plus one entity
* @throws SAXException if the characters could not be written
*/
private int writeCharsAndEntity(char[] ch, int from, int to, String entity)
throws SAXException {
super.characters(ch, from, to - from);
write('&');
write(entity);
write(';');
return to + 1;
}
/**
* Writes the given characters with XML meta characters escaped.
*
* @param ch character array
* @param from start position in the array
* @param to end position in the array
* @param attribute whether the characters should be escaped as
* an attribute value or normal character content
* @throws SAXException if the characters could not be written
*/
private void writeEscaped(char[] ch, int from, int to, boolean attribute)
throws SAXException {
int pos = from;
while (pos < to) {
if (ch[pos] == '<') {
from = pos = writeCharsAndEntity(ch, from, pos, "lt");
} else if (ch[pos] == '>') {
from = pos = writeCharsAndEntity(ch, from, pos, "gt");
} else if (ch[pos] == '&') {
from = pos = writeCharsAndEntity(ch, from, pos, "amp");
} else if (attribute && ch[pos] == '"') {
from = pos = writeCharsAndEntity(ch, from, pos, "quot");
} else {
pos++;
}
}
super.characters(ch, from, to - from);
}
}