问题
I am dealing with an already created Document object. I have to be able to set it's base namespace (attribute name "xmlns") to certain value. My input is DOM and is something like:
<root>...some content...</root>
What I need is DOM which is something like:
<root xmlns="myNamespace">...some content...</root>
That's it. Easy, isn't it? Wrong! Not with DOM!
I have tried the following:
1) Using doc.getDocumentElement().setAttribute("xmlns","myNamespace")
I get a document with empty xmlns (it works on any other attribute name!)
<root xmlns="">...</root>
2) Using renameNode(...)
First clone the document:
Document input = /*that external Document whose namespace I want to alter*/;
DocumentBuilderFactory BUILDER_FACTORY_NS = DocumentBuilderFactory.newInstance();
BUILDER_FACTORY_NS.setNamespaceAware(true);
Document output = BUILDER_NS.newDocument();
output.appendChild(output.importNode(input.getDocumentElement(), true));
I'm really missing document.clone(), but perhaps it's just me.
Now rename the root node:
output.renameNode(output.getDocumentElement(),"myNamespace",
output.getDocumentElement().getTagName());
Now isn't that straightforward? ;)
What I get now is:
<root xmlns="myNamespace">
<someElement xmlns=""/>
<someOtherElement xmlns=""/>
</root>
So (as all of us have expected, right?), this renames the namespace only of the the root node.
Curse you, DOM!
Is there any way to do this recursively (without writing an own recursive method)?
Please help ;)
Please don't advice me to do some fancy workaround, such as transforming DOM to something else, alter the namespace there, and transform it back. I need DOM because it's the fastest standard way to manipulate XML.
Note: I'm using the latest JDK.
EDIT
Removed wrong assumptions from the question, which had to do with namespace prefix.
回答1:
I had the very same problem today. I ended up using parts of @ivan_ivanovich_ivanoff answer but removed the recursion and fixed some bugs.
Very important: if old namespace is null you must add two translations, one from null to your new namespaceURI and another from "" to your new namespaceURI. This happens because the first call to renameNode will change existing nodes that have a null namespaceURI to xmlns="".
Example of usage:
Document xmlDoc = ...;
new XmlNamespaceTranslator()
.addTranslation(null, "new_ns")
.addTranslation("", "new_ns")
.translateNamespaces(xmlDoc);
// xmlDoc will have nodes with namespace null or "" changed to "new_ns"
Full source code follows:
public class XmlNamespaceTranslator {
private Map<Key<String>, Value<String>> translations = new HashMap<Key<String>, Value<String>>();
public XmlNamespaceTranslator addTranslation(String fromNamespaceURI, String toNamespaceURI) {
Key<String> key = new Key<String>(fromNamespaceURI);
Value<String> value = new Value<String>(toNamespaceURI);
this.translations.put(key, value);
return this;
}
public void translateNamespaces(Document xmlDoc) {
Stack<Node> nodes = new Stack<Node>();
nodes.push(xmlDoc.getDocumentElement());
while (!nodes.isEmpty()) {
Node node = nodes.pop();
switch (node.getNodeType()) {
case Node.ATTRIBUTE_NODE:
case Node.ELEMENT_NODE:
Value<String> value = this.translations.get(new Key<String>(node.getNamespaceURI()));
if (value != null) {
// the reassignment to node is very important. as per javadoc renameNode will
// try to modify node (first parameter) in place. If that is not possible it
// will replace that node for a new created one and return it to the caller.
// if we did not reassign node we will get no childs in the loop below.
node = xmlDoc.renameNode(node, value.getValue(), node.getNodeName());
}
break;
}
// for attributes of this node
NamedNodeMap attributes = node.getAttributes();
if (!(attributes == null || attributes.getLength() == 0)) {
for (int i = 0, count = attributes.getLength(); i < count; ++i) {
Node attribute = attributes.item(i);
if (attribute != null) {
nodes.push(attribute);
}
}
}
// for child nodes of this node
NodeList childNodes = node.getChildNodes();
if (!(childNodes == null || childNodes.getLength() == 0)) {
for (int i = 0, count = childNodes.getLength(); i < count; ++i) {
Node childNode = childNodes.item(i);
if (childNode != null) {
nodes.push(childNode);
}
}
}
}
}
// these will allow null values to be stored on a map so that we can distinguish
// from values being on the map or not. map implementation returns null if the there
// is no map element with a given key. If the value is null there is no way to
// distinguish from value not being on the map or value being null. these classes
// remove ambiguity.
private static class Holder<T> {
protected final T value;
public Holder(T value) {
this.value = value;
}
public T getValue() {
return value;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((value == null) ? 0 : value.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Holder<?> other = (Holder<?>) obj;
if (value == null) {
if (other.value != null)
return false;
} else if (!value.equals(other.value))
return false;
return true;
}
}
private static class Key<T> extends Holder<T> {
public Key(T value) {
super(value);
}
}
private static class Value<T> extends Holder<T> {
public Value(T value) {
super(value);
}
}
}
回答2:
In addition to setting the prefix, you must also declare your namespace somewhere.
[EDIT] If you look into the package org.w3c.dom, you'll notice that there is no support for namespaces whatsoever except that you can create a Document node with a namespace URI:
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(true);
DocumentBuilder builder = factory.newDocumentBuilder();
DOMImplementation DOMImplementation = builder.getDOMImplementation();
Document doc = DOMImplementation.createDocument(
"http://www.somecompany.com/2005/xyz", // namespace
"root",
null /*DocumentType*/);
Element root = doc.getDocumentElement();
root.setPrefix("xyz");
root.setAttribute(
"xmlns:xyz",
"http://www.somecompany.com/2005/xyz");
With the standard W3C DOM API of Java 5 (and up), it's not possible to modify the namespace of a node.
But the W3C DOM API is just a couple of interfaces. So what you should try is to look at the implementation (i.e. the actual class of your document instance), cast it to the real type. This type should have additional methods and if you're lucky, you can use those to modify the namespace.
回答3:
Well, here goes the recursive "solution":
(I still hope that someone might find a better way to do this)
public static void renameNamespaceRecursive(Document doc, Node node,
String namespace) {
if (node.getNodeType() == Node.ELEMENT_NODE) {
System.out.println("renaming type: " + node.getClass()
+ ", name: " + node.getNodeName());
doc.renameNode(node, namespace, node.getNodeName());
}
NodeList list = node.getChildNodes();
for (int i = 0; i < list.getLength(); ++i) {
renameNamespaceRecursive(doc, list.item(i), namespace);
}
}
Seems to work, although I don't know if it's correct to rename only the node type ELEMENT_NODE, or if other node types must be renamed.
回答4:
we can change the xml namespace using sax parser, try this
import java.util.ListIterator;
import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.Namespace;
import org.dom4j.QName;
import org.dom4j.Visitor;
import org.dom4j.VisitorSupport;
import org.dom4j.io.SAXReader;
public class VisitorExample {
public static void main(String[] args) throws Exception {
Document doc = new SAXReader().read("test.xml");
Namespace oldNs = Namespace.get("oldNamespace");
Namespace newNs = Namespace.get("newPrefix", "newNamespace");
Visitor visitor = new NamespaceChangingVisitor(oldNs, newNs);
doc.accept(visitor);
System.out.println(doc.asXML());
}
}
class NamespaceChangingVisitor extends VisitorSupport {
private Namespace from;
private Namespace to;
public NamespaceChangingVisitor(Namespace from, Namespace to) {
this.from = from;
this.to = to;
}
public void visit(Element node) {
Namespace ns = node.getNamespace();
if (ns.getURI().equals(from.getURI())) {
QName newQName = new QName(node.getName(), to);
node.setQName(newQName);
}
ListIterator namespaces = node.additionalNamespaces().listIterator();
while (namespaces.hasNext()) {
Namespace additionalNamespace = (Namespace) namespaces.next();
if (additionalNamespace.getURI().equals(from.getURI())) {
namespaces.remove();
}
}
}
}
回答5:
A slight variation of Ivan's original post worked for me: setting the attribute on the document node.
xslRoot.setAttribute("xmlns:fo", "http://www.w3.org/1999/XSL/Format");
where
- xslRoot is the document/root element/node,
- fo is the namespace ID
Hope that helps someone!
Mike Watts
回答6:
If you are ok with using the Xerces classes, you can create a DOMParser that replaces the URI of attributes and elements with your fixed up URIs:
import org.apache.xerces.parsers.DOMParser;
public static class MyDOMParser extends DOMParser {
private Map<String, String> fixupMap = ...;
@Override
protected Attr createAttrNode(QName attrQName)
{
if (fixupMap.containsKey(attrQName.uri))
attrQName.uri = fixupMap.get(attrQName.uri);
return super.createAttrNode(attrQName);
}
@Override
protected Element createElementNode(QName qName)
{
if (fixupMap.containsKey(qName.uri))
qName.uri = fixupMap.get(qName.uri);
return super.createElementNode(qName);
}
}
The elsewhere, you can parse the
DOMParse p = new MyDOMParser(...);
p.parse(new InputSource(inputStream));
Document doc = p.getDocument();
回答7:
Let's say you've got your Document instance..
import org.dom4j.*;
{
static final String YOUR_NAMESPACE_PREFIX = "PREFIX";
static final String YOUR_NAMESPACE_URI = "URI";
Document document = ...
//now get the root element
Element element = document.getRootElement();
renameNamespaceRecursive(element);
...
//End of this method
}
//the recursive method for the operation
void renameNamespaceRecursive(Element element) {
element.setQName(new QName(element.getName(), DocumentHelper.createNamespace(YOUR_NAMESPACE_PREFIX, YOUR_NAMESPACE_URI)));
for (Iterator i = element.elementIterator(); i.hasNext();) {
renameNamespaceRecursive((Element)i.next());
}
}
That should do.
回答8:
I solved using org.jdom.Element:
Java:
import org.jdom.Element;
...
Element kml = new Element("kml", "http://www.opengis.net/kml/2.2");
XML:
<kml xmlns="http://www.opengis.net/kml/2.2">;
...
</kml>
来源：https://stackoverflow.com/questions/1492428/javadom-how-do-i-set-the-base-namespace-of-an-already-created-document