Java Tutorial/XML/Attribute

Accessing attributes of an element

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
public class Main {
  public static void main(String[] argv) throws Exception {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder loader = factory.newDocumentBuilder();
    Document document = loader.parse("sample.xml");
    Element purchaseOrder = document.getDocumentElement();
    Attr orderDate = purchaseOrder.getAttributeNode("date");
    System.out.println(orderDate.getValue());
    NamedNodeMap attrs = purchaseOrder.getAttributes();
    int attrsCount = attrs.getLength();
    for (int i = 0; i < attrsCount; i++) {
      Attr item = (Attr) attrs.item(i);
      System.out.println(""" + item.getName() + "" = "" + item.getValue() + """);
    }
  }
}

Adding and Removing an Attribute in a DOM Element

import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
public class Main {
  public static void main(String[] argv) throws Exception {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);
    factory.setExpandEntityReferences(false);
    Document doc = factory.newDocumentBuilder().parse(new File("filename"));
    Element element = doc.getElementById("key1");
    element.setAttribute("newAttrName", "attrValue");
    element.setAttribute("newAttrName", "<>&\""");
    element.removeAttribute("value");
    boolean has = element.hasAttribute("value"); // true
    String attrValue = element.getAttribute("value"); // mydefault
  }
}

Determining If an Attribute Was Supplied in a DOM Element

import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
public class Main {
  public static void main(String[] argv) throws Exception{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);
    factory.setExpandEntityReferences(false);
    Document doc = factory.newDocumentBuilder().parse(new File("filename"));
    Element element = doc.getElementById("key1");
    Attr attr = (Attr) element.getAttributeNode("attrName");
    boolean wasSpecified = attr != null && attr.getSpecified();
  }
}

Extracting attribute values from XML elements

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class Main {
  public static void main(String[] argv) throws Exception {
    SAXParserFactory factory = SAXParserFactory.newInstance();
    SAXParser parser = factory.newSAXParser();
    SaxHandler handler = new SaxHandler();
    parser.parse("sample.xml", handler);
  }
}
class SaxHandler extends DefaultHandler {
  public void startElement(String uri, String localName, String qName, Attributes attrs)
      throws SAXException {
    if (qName.equals("order")) {
      String date = attrs.getValue("date");
      String number = attrs.getValue("number");
      System.out.println("Order #" + number + " date is "" + date + """);
    }
  }
}

Getting and Setting an Attribute in a DOM Element

import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
public class Main {
  public static void main(String[] argv) throws Exception {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);
    factory.setExpandEntityReferences(false);
    Document doc = factory.newDocumentBuilder().parse(new File("filename"));
    Element element = doc.getElementById("key1");
    boolean has = element.hasAttribute("value"); 
    String attrValue = element.getAttribute("value"); 
    element.setAttribute("value", "newValue1");
    element = doc.getElementById("key2");
    has = element.hasAttribute("value"); 
    attrValue = element.getAttribute("value"); 
    element.setAttribute("value", "a<\""&>z");
  }
}

Listing All the Attributes of a DOM Element

import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
public class Main {
  public static void main(String[] argv) throws Exception{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);
    factory.setExpandEntityReferences(false);
    Document doc = factory.newDocumentBuilder().parse(new File("filename"));
    Element element = doc.getElementById("key1");
    NamedNodeMap attrs = element.getAttributes();
    int numAttrs = attrs.getLength();
    for (int i = 0; i < numAttrs; i++) {
      Attr attr = (Attr) attrs.item(i);
      String attrName = attr.getNodeName();
      String attrValue = attr.getNodeValue();
    }
  }
}

Remove all attributes by first making a copy of the attribute names and then using the list to remove the attributes:

import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
public class Main {
  public static void main(String[] argv) throws Exception{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);
    factory.setExpandEntityReferences(false);
    Document doc = factory.newDocumentBuilder().parse(new File("filename"));
    Element element = doc.getElementById("key1");
    NamedNodeMap attrs = element.getAttributes();
    String[] names = new String[attrs.getLength()];
    for (int i = 0; i < names.length; i++) {
      names[i] = attrs.item(i).getNodeName();
    }
    for (int i = 0; i < names.length; i++) {
      attrs.removeNamedItem(names[i]);
    }
  }
}

Removing All the Attributes in a DOM Element

import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
public class Main {
  public static void main(String[] argv) throws Exception{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    factory.setValidating(true);
    factory.setExpandEntityReferences(false);
    Document doc = factory.newDocumentBuilder().parse(new File("filename"));
    Element element = doc.getElementById("key1");
    NamedNodeMap attrs = element.getAttributes();
    while (attrs.getLength() > 0) {
      attrs.removeNamedItem(attrs.item(0).getNodeName());
    }
  }
}