Reading multi-node and attribute XML in Java

Question

My XML is as follows:-

<myxml>
    <resource name='book'>
        <acl>
            <ace person='bob' rights='rw' />
            <ace person='john' rights='w' />
        </acl>
    </resource>

    <resource name='dvd'>
        <acl>
            <ace person='bob' rights='w' />
        </acl>
    </resource>
</myxml>

I am having trouble reading this XML document.

Here is the code I tried.

    DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory
                .newInstance();
        DocumentBuilder documentBuilder = documentBuilderFactory
                .newDocumentBuilder();
        Document document = documentBuilder.parse(new File(fileName));

    Element rootElement = xmlDocument.getDocumentElement();

    NodeList resourceList= rootElement.getElementsByTagName("resource");
    for (int i = 0; i < resourceList.getLength(); i++) {
        Node node = resourceList.item(i);
        Element element = (Element) node;
        String resourceName= element.getAttribute("name");
    }

Basically I want to print like "this book can be used by this person with xyz permission".

I can get the name of the book by String objectName= element.getAttribute("name") . After this I can't go.

I tried by getting child nodes but keep on getting nulls.

Any suggestions?

Answer 1

One option is use element.getElementsByTagName("ace") to retrieve the ace elements you're looking for:

    NodeList aceList = element.getElementsByTagName("ace");
    for(int j= 0; j < aceList.getLength(); j++){
        Element ace = (Element) aceList.item(j);
        String person = ace.getAttribute("person");
    }

Answer 2

You just need another for loop nested inside to process <ace> elements.

NodeList resourceList = rootElement.getElementsByTagName("resource");
for (int i = 0; i < resourceList.getLength(); i++) {
    Element resource = (Element) resourceList.item(i);
    String book = resource.getAttribute("name");
    NodeList aceList = resource.getElementsByTagName("ace");
    for (int j = 0; j < aceList.getLength(); j++) {
        Element ace = (Element) aceList.item(j);
        System.out.println("'" + book + "' can be used by '"
                + ace.getAttribute("person") + "' with '"
                + ace.getAttribute("rights") + "' permission.");
    }
}

Output :

'book' can be used by 'bob' with 'rw' permission.
'book' can be used by 'john' with 'w' permission.
'dvd' can be used by 'bob' with 'w' permission.