Java Tips - Reading a DOM tree from XML document

DOM is a high-level API for processing XML data. DOM uses SAX to analyze the source. The difference from SAX is that there is no need to handle XML element directly. Entire document is composed and returned by a DocumentBuilder instance. Sample below shows ordinary loading of XML using DOM:


import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.parsers.FactoryConfigurationError;

import javax.xml.parsers.ParserConfigurationException;

import org.xml.sax.SAXException;



import org.w3c.dom.*;



/**

 * This sample program shows how to load XML data

 * using DOM interface.

 */



public class Test {

  public static void main(String[] args) {

    try {

      // first of all we request out 

      // DOM-implementation:

      DocumentBuilderFactory factory = 

        DocumentBuilderFactory.newInstance();

      // then we have to create document-loader:

      DocumentBuilder loader = factory.newDocumentBuilder();



      // loading a DOM-tree...

      Document document = loader.parse("sample.xml");

      // at last, we get a root element:

      Element tree = document.getDocumentElement();



      // ... do something with document element ...



    } catch (IOException ex) {

      // any IO errors occur:

      handleError(ex);

    } catch (SAXException ex) {

      // parse errors occur:

      handleError(ex);

    } catch (ParserConfigurationException ex) {

      // document-loader cannot be created which,

      // satisfies the configuration requested

      handleError(ex);

    } catch (FactoryConfigurationError ex) {

      // DOM-implementation is not available 

      // or cannot be instantiated:

      handleError(ex);

    }

  }



  private static final void handleError(Throwable ex) {

    // ... handle error here...

  }

}

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