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/*
* Copyright 2004,2005 The Apache Software Foundation.
*
* Licensed 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.tuscany.sdo.util.resource;
import javax.xml.namespace.NamespaceContext;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;
/**
* The XMLStreamSerializer pulls events from the XMLStreamReader and dumps into the XMLStreamWriter
*/
public class XMLStreamSerializer implements XMLStreamConstants {
private static int namespaceSuffix = 0;
public static final String NAMESPACE_PREFIX = "ns";
/*
* The behavior of the serializer is such that it returns when it encounters the starting element for the second time. The depth variable tracks
* the depth of the serilizer and tells it when to return. Note that it is assumed that this serialization starts on an Element.
*/
/**
* Field depth
*/
private int depth = 0;
/**
* Method serialize.
*
* @param node
* @param writer
* @throws XMLStreamException
*/
public void serialize(XMLStreamReader node, XMLStreamWriter writer) throws XMLStreamException {
serializeNode(node, writer);
}
/**
* Method serializeNode.
*
* @param reader
* @param writer
* @throws XMLStreamException
*/
protected void serializeNode(XMLStreamReader reader, XMLStreamWriter writer) throws XMLStreamException {
// TODO We get the StAXWriter at this point and uses it hereafter assuming that this is the only entry point to this class.
// If there can be other classes calling methodes of this we might need to change methode signatures to OMOutputer
while (reader.hasNext()) {
int event = reader.next();
if (event == START_ELEMENT) {
serializeElement(reader, writer);
depth++;
} else if (event == ATTRIBUTE) {
serializeAttributes(reader, writer);
} else if (event == CHARACTERS) {
serializeText(reader, writer);
} else if (event == COMMENT) {
serializeComment(reader, writer);
} else if (event == CDATA) {
serializeCData(reader, writer);
} else if (event == END_ELEMENT) {
serializeEndElement(writer);
depth--;
} else if (event == START_DOCUMENT) {
depth++; // if a start document is found then increment the depth
} else if (event == END_DOCUMENT) {
if (depth != 0)
depth--; // for the end document - reduce the depth
try {
serializeEndElement(writer);
} catch (Exception e) {
// TODO: log exceptions
}
}
if (depth == 0) {
break;
}
}
}
/**
* @param reader
* @param writer
* @throws XMLStreamException
*/
protected void serializeElement(XMLStreamReader reader, XMLStreamWriter writer) throws XMLStreamException {
String prefix = reader.getPrefix();
String nameSpaceName = reader.getNamespaceURI();
if (nameSpaceName != null) {
String writer_prefix = writer.getPrefix(nameSpaceName);
if (writer_prefix != null) {
writer.writeStartElement(nameSpaceName, reader.getLocalName());
} else {
if (prefix != null) {
writer.writeStartElement(prefix, reader.getLocalName(), nameSpaceName);
writer.writeNamespace(prefix, nameSpaceName);
writer.setPrefix(prefix, nameSpaceName);
} else {
writer.writeStartElement(nameSpaceName, reader.getLocalName());
writer.writeDefaultNamespace(nameSpaceName);
writer.setDefaultNamespace(nameSpaceName);
}
}
} else {
writer.writeStartElement(reader.getLocalName());
}
// add the namespaces
int count = reader.getNamespaceCount();
String namespacePrefix;
for (int i = 0; i < count; i++) {
namespacePrefix = reader.getNamespacePrefix(i);
if (namespacePrefix != null && namespacePrefix.length() == 0)
continue;
serializeNamespace(namespacePrefix, reader.getNamespaceURI(i), writer);
}
// add attributes
serializeAttributes(reader, writer);
}
/**
* Method serializeEndElement.
*
* @param writer
* @throws XMLStreamException
*/
protected void serializeEndElement(XMLStreamWriter writer) throws XMLStreamException {
writer.writeEndElement();
}
/**
* @param reader
* @param writer
* @throws XMLStreamException
*/
protected void serializeText(XMLStreamReader reader, XMLStreamWriter writer) throws XMLStreamException {
writer.writeCharacters(reader.getText());
}
/**
* Method serializeCData.
*
* @param reader
* @param writer
* @throws XMLStreamException
*/
protected void serializeCData(XMLStreamReader reader, XMLStreamWriter writer) throws XMLStreamException {
writer.writeCData(reader.getText());
}
/**
* Method serializeComment.
*
* @param reader
* @param writer
* @throws XMLStreamException
*/
protected void serializeComment(XMLStreamReader reader, XMLStreamWriter writer) throws XMLStreamException {
writer.writeComment(reader.getText());
}
/**
* @param reader
* @param writer
* @throws XMLStreamException
*/
protected void serializeAttributes(XMLStreamReader reader, XMLStreamWriter writer) throws XMLStreamException {
int count = reader.getAttributeCount();
String prefix = null;
String namespaceName = null;
String writerPrefix = null;
for (int i = 0; i < count; i++) {
prefix = reader.getAttributePrefix(i);
namespaceName = reader.getAttributeNamespace(i);
if (namespaceName != null)
writerPrefix = writer.getNamespaceContext().getPrefix(namespaceName);
if (!"".equals(namespaceName)) {
// prefix has already being declared but this particular attrib has a
// no prefix attached. So use the prefix provided by the writer
if (writerPrefix != null && (prefix == null || prefix.equals(""))) {
writer.writeAttribute(writerPrefix, namespaceName, reader.getAttributeLocalName(i), reader.getAttributeValue(i));
// writer prefix is available but different from the current
// prefix of the attrib. We should be decalring the new prefix
// as a namespace declaration
} else if (prefix != null && !"".equals(prefix) && !prefix.equals(writerPrefix)) {
writer.writeNamespace(prefix, namespaceName);
writer.writeAttribute(prefix, namespaceName, reader.getAttributeLocalName(i), reader.getAttributeValue(i));
// prefix is null (or empty), but the namespace name is valid! it has not
// being written previously also. So we need to generate a prefix
// here
} else {
prefix = generateUniquePrefix(writer.getNamespaceContext());
writer.writeNamespace(prefix, namespaceName);
writer.writeAttribute(prefix, namespaceName, reader.getAttributeLocalName(i), reader.getAttributeValue(i));
}
} else {
// empty namespace is equal to no namespace!
writer.writeAttribute(reader.getAttributeLocalName(i), reader.getAttributeValue(i));
}
}
}
/**
* Generates a unique namespace prefix that is not in the scope of the NamespaceContext
*
* @param nsCtxt
* @return string
*/
private String generateUniquePrefix(NamespaceContext nsCtxt) {
String prefix = NAMESPACE_PREFIX + namespaceSuffix++;
// null should be returned if the prefix is not bound!
while (nsCtxt.getNamespaceURI(prefix) != null) {
prefix = NAMESPACE_PREFIX + namespaceSuffix++;
}
return prefix;
}
/**
* Method serializeNamespace.
*
* @param prefix
* @param URI
* @param writer
* @throws XMLStreamException
*/
private void serializeNamespace(String prefix, String URI, XMLStreamWriter writer) throws XMLStreamException {
String prefix1 = writer.getPrefix(URI);
if (prefix1 == null) {
writer.writeNamespace(prefix, URI);
writer.setPrefix(prefix, URI);
}
}
}
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