How to get the attribute value of an xml node using java

Question

I have an xml which looks like this:

{ <xml><ep><source type="xml">...</source><source type="text">..</source></ep></xml>}

Here I want to retrieve the value of "source type" where type is an attribute.

I tried the following, which didn't work:

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
try {
    DocumentBuilder builder = domFactory.newDocumentBuilder();
    Document dDoc = builder.parse("D:/workspace1/ereader/src/main/webapp/configurations/config.xml");
    System.out.println(dDoc);
    XPath xPath = XPathFactory.newInstance().newXPath();
    Node node = (Node) xPath.evaluate("//xml/source/@type/text()", dDoc, XPathConstants.NODE);
    System.out.println(node);
} catch (Exception e) {
    e.printStackTrace();

This also didn't work:

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
InputSource is = new InputSource(new StringReader("config.xml"));
Document doc = builder.parse(is);

NodeList nodeList = doc.getElementsByTagName("source");

for (int i = 0; i < nodeList.getLength(); i++) {
    Node node = nodeList.item(i);

    if (node.hasAttributes()) {
        Attr attr = (Attr) node.getAttributes().getNamedItem("type");
        if (attr != null) {
            String attribute = attr.getValue();
            System.out.println("attribute: " + attribute);
        }
    }
}

Babism

Have u tried using VTD-XML vtd-xml.sourceforge.net It is faster and more memory efficient. – Cathleencathlene

hi Rosdi, No i've n't tried, anyways ATR's code works fine, and my snippet too:) thanks for ur kind response – Babism

Answer 1

Since your question is more generic so try to implement it with XML Parsers available in Java .If you need it in specific to parsers, update your code here what you have tried yet

<?xml version="1.0" encoding="UTF-8"?>
<ep>
    <source type="xml">TEST</source>
    <source type="text"></source>
</ep>

DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse("uri to xmlfile");
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("//ep/source[@type]");
NodeList nl = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);

for (int i = 0; i < nl.getLength(); i++)
{
    Node currentItem = nl.item(i);
    String key = currentItem.getAttributes().getNamedItem("type").getNodeValue();
    System.out.println(key);
}

Caracole

i've tried the above snippet and i dono to proceed with, kindly help me!! i need to get the value "xml" and "text" alone. that's my requirement. – Babism

ATR, Its actually //xml/ep/source/@type i've edited few statements in ur code.. and it works fine.. thanks :) – Babism

Is there a way i can get the value in between the tags, in above sample, <source type="xml">TEST</source>, how can i read TEST – Cloudberry

Answer 2

try something like this :

    DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    Document dDoc = builder.parse("d://utf8test.xml");

    XPath xPath = XPathFactory.newInstance().newXPath();
    NodeList nodes = (NodeList) xPath.evaluate("//xml/ep/source/@type", dDoc, XPathConstants.NODESET);
    for (int i = 0; i < nodes.getLength(); i++) {
        Node node = nodes.item(i);
        System.out.println(node.getTextContent());
    }

please note the changes :

• we ask for a nodeset (XPathConstants.NODESET) and not only for a single node.
• the xpath is now //xml/ep/source/@type and not //xml/source/@type/text()

PS: can you add the tag java to your question ? thanks.

Myrilla

mabroukb, thanks:) added java tag:) ur explanations made me clear.. Thanks alot!! – Babism

Answer 3

I'm happy that this snippet works fine:

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.parse(new File("config.xml"));
NodeList nodeList = document.getElementsByTagName("source");
for(int x=0,size= nodeList.getLength(); x<size; x++) {
    System.out.println(nodeList.item(x).getAttributes().getNamedItem("type").getNodeValue());
} 

Babism

Answer 4

use

document.getElementsByTagName(" * ");

to get all XML elements from within an XML file, this does however return repeating attributes

example:

NodeList list = doc.getElementsByTagName("*");

System.out.println("XML Elements: ");

        for (int i=0; i<list.getLength(); i++) {

            Element element = (Element)list.item(i);
            System.out.println(element.getNodeName());
        }

Rushton

Answer 5

Below is the code to do it in VTD-XML

import com.ximpleware.*;

public class queryAttr{
     public static void main(String[] s) throws VTDException{
         VTDGen vg= new VTDGen();
         if (!vg.parseFile("input.xml", false))
            return false;
         VTDNav vn = vg.getNav();
         AutoPilot ap = new AutoPilot(vn);
         ap.selectXPath("//xml/ep/source/@type");
         int i=0;
         while((i = ap.evalXPath())!=-1){
               system.out.println(" attr val ===>"+ vn.toString(i+1));

         }
     }
}

Mention

Answer 6

public static void main(String[] args) throws IOException {
    String filePath = "/Users/myXml/VH181.xml";
    File xmlFile = new File(filePath);
    DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
    DocumentBuilder dBuilder;
    try {
        dBuilder = dbFactory.newDocumentBuilder();
        Document doc = dBuilder.parse(xmlFile);
        doc.getDocumentElement().normalize();
        printElement(doc);
        System.out.println("XML file updated successfully");
    } catch (SAXException | ParserConfigurationException e1) {
        e1.printStackTrace();
    }
}
private static void printElement(Document someNode) {
    NodeList nodeList = someNode.getElementsByTagName("choiceInteraction");
    for(int z=0,size= nodeList.getLength();z<size; z++) {
            String Value = nodeList.item(z).getAttributes().getNamedItem("id").getNodeValue();
            System.out.println("Choice Interaction Id:"+Value);
        }
    }

we Can try this code using method

Spacing

Answer 7

Below is the utility method I have written to get value of any node from the root Document object and a given XPATH.

public String getValue(Document doc, String xPath) throws Exception {
   XPathFactory factory = XPathFactory.newInstance();
   XPath path = factory.newXPath();
   XPathExpression expression = path.compile(xPath);
   Node node = (Node) expression.evaluate(doc,XPathConstants.NODE);
   return node.getFirstChild().getNodeValue();
}

All the libraries are from java.xml.xpath and org.w3c.dom.

Now all you need the root document element and correct Path. For your example if will /ep/source/@type

So, basically XPAth is to navigate till the element you are after and followed by /@attributeName you are interested in.

Please node /ep/source@type won't work. (I wasted 30 min troubleshooting this).

Tafoya