How to remove the root node of an XML document with DOM

Question

I want to remove the wrapper from the following XML document using the DOM api

<hs:PageWrapper>
    <div id="botton1"/>
    <div id="botton2"/>
</hs:PageWrapper>

so that I will only have these as the final output:

<div id="botton1"/>
<div id="botton2"/>

How can i do this in Java?

The output you want is not a valid XML document. You would have to create two separate documents and serialize them one after the other. Why do you want to produce an invalid document? — Jim Garrison
– Jim Garrison, Commented Nov 16, 2010 at 21:33

corriganjc · Accepted Answer · 2010-11-16 22:34:00Z

5

What you want to do will not result in well formed XML as there will be 2 elements at the document root. However, code to do what you want is below. It gets the child nodes of the wrapper element, creates a new document for each node, imports the node into the document and writes the document into a String.

    public String peel(String xmlString) {
    StringWriter writer = new StringWriter();
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    try {
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document document = builder.parse(new InputSource(new StringReader(
                xmlString)));
        NodeList nodes = document.getDocumentElement().getChildNodes();
        for (int i = 0; i < nodes.getLength(); i++) {
            Node n = nodes.item(i);
            Document d = builder.newDocument();
            Node newNode = d.importNode(n, true);
            d.insertBefore(newNode, null);
            writeOutDOM(d, writer);
        }
    } catch (ParserConfigurationException e) {
        e.printStackTrace();
    } catch (SAXException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (TransformerFactoryConfigurationError e) {
        e.printStackTrace();
    } catch (TransformerException e) {
        e.printStackTrace();
    }
    return writer.toString();
}

protected void writeOutDOM(Document doc, Writer writer) 
     throws TransformerFactoryConfigurationError, TransformerException {
    Result result = new StreamResult(writer);
    DOMSource domSource = new DOMSource(doc);
    Transformer transformer = TransformerFactory.newInstance()
            .newTransformer();
    transformer.setOutputProperty("omit-xml-declaration", "yes");
    transformer.transform(domSource, result);
}

edited Nov 16, 2010 at 22:34

answered Nov 16, 2010 at 21:57

corriganjc

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5 Comments

Farouk Alhassan Over a year ago

Hi Thank you very much for that. I tried that and I got an error the following error : HIERARCHY_REQUEST_ERR: An attempt was made to insert a node where it is not permitted. this occured on line d.appendChild(newNode);

corriganjc Over a year ago

Hmmm. I tried it before I posted the answer, and it worked. I am using SUN JDK 6 on Linux. What are you using?

corriganjc Over a year ago

@Farouk, I have made a small change to the code. I replaced appendChild with insertBefore.

Farouk Alhassan Over a year ago

Hi thank you very much. I think the best way is to use dump the XML straight in the document without a root element as its creating an unnecessary overhead. Thanks for your help anyway. I think the solution you gave is conceptually correct so will mark it as such

corriganjc Over a year ago

Glad I could help. Do note, that for a well formed XML document, you can only have one element at the root level, so if you need to parse the document again, you'll need the root element.

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