1. WaysInJavaToParseXML
Prof: Dr. Shu-Ching Chen
TA: Sheng Guan

2. Parse XML with Java DOM API
How to do this ?
The Java DOM API for XML parsing is intended for working with XML as an object graph in memory - a "Document Object Model (DOM)".
The parser traverses the XML file and creates the corresponding DOM objects.
DOM objects are linked together in a tree structure.

3. Object model ( DOM Tree)

4. Steps: 1. Creating A Java DOM XML Parser
2. Parsing XML with a Java DOM Parser
3.Java DOM: Get the Document Object

5. XML file and corresponding DOM structure
<book>
<title>Fun Software</title>
<author>Jakob Jenkov</author>
<ISBN> </ISBN>
</book>

6. DOM - 3 pieces of XML 1. Elements (sometimes called tags)
2. Attributes
3. The data (also called values) that the elements and attributes describe

7. Step 1: Creating a Java DOM XML parser
Creating a Java DOM XML parser is done using the javax.xml.parsers.DocumentBuilderFactory class. Here is an example:
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = null;
try {
builder = builderFactory.newDocumentBuilder();
} catch (ParserConfigurationException e) {
e.printStackTrace(); }

8. Step 2: Parsing an XML file into a DOM tree
try {
Document document = builder.parse( new FileInputStream("/path/to/your/file.xml"));
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) { }

9. Step 3: Java DOM: Get the Document Object
You are now ready to traverse the Document instance you have received from the DocumentBuilder;
The DOM Document object represents an XML document. When you parse an XML file using a Java DOM parser, you get back a Document object.

10. The DOM Document Element
The two most commonly used features of DOM are:
1.Accessing Child Elements of an Element
2.Accessing Attributes of an Element
A DOM object contains a lot of different nodes connected in a tree-like structure. At the top is the Document object.
The Document object has a single root element, which is returned by calling getDocumentElement():
Element rootElement = document.getDocumentElement();

11. DOM Elements, Child Elements, and the Node Interface
The root element has children. You get the children of an element like this:
NodeList nodes = element.getChildNodes();
for(int i=0; i<nodes.getLength(); i++){
Node node = nodes.item(i);
if(node instanceof Element){
//a child element to process
Element child = (Element) node;
String attribute = child.getAttribute("width"); }

12. DOM Element Attributes
The getChildNodes() method returns a NodeList object, which is a list of Node elements.
The Node interface is a superinterface for all of the different node types in DOM
The Element interface extends Node and you can access the attributes of an element via the Element interface:
String attrValue = element.getAttribute("attrName");

13. Examine sub-elements
//returns a list of subelements of specified name getElementsByTagName("subelementName"); //returns a list of all child nodes getChildNodes(); A whole complete example is in the below link: parse_document.htm

14. Reference
using-dom-sax-and-stax-parser-in-java/
11/b28394/adx_j_parser.html
_parse_document.htm
Drafting out the sample input forms, queries and reports, often helps.