How to parse Xml file -- DOM!

Posted 2020-09-27 pp_crz_coder

We can see that when we want to use the Dom4j to parse XML , we should import org.dom4j.*

At the same time ,that to parse XML by DOM ,we should import org.w3c.dom.*

The conclusion is that DOM and Dom4j is different and located in different jar.The DOM belongs to w3c and the Dom4j belongs to dom4j.

But how do we parse XML by DOM?

　　//1.get the DocumentBuilderFactory by its static method

　　DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

　　//2.get the DocumentBuilder by DocumentBuilderFactory‘s newDocumentBuilder() method

　　DocumentBuilder builder = factory.newDocumentBuilder();

　　//3.get the Document object by DocumentBuilder

　　Document document = DocumentBuilder.parse("book.xml");

　　//4.to handle the document further ,we can use getElementByTagName("") method get the NodeList

　　NodeList list = document.getElementByTagName("");

　　//5.get the single specific node

　　Node node = list.item(0);

　　//6.print the node‘s text content

　　System.out.println(node.getTextContent());

 

To improve the effeciency of using DOM to parse XML , write a util is not a bad idea,isn‘t it?

public class DOMUtils{

　　public static Document getDocument(String path){

　　　　return DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(path);

　　}

　　

　　public static Document getDocument(File file){

　　　　return DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(path);

　　}

 

　　public void writeXml2File(Document document,String path){

　　　　TransformerFactory.newInstance().newTransformer.transform(new DOMSource(document),new StreamResult(path));

　　}

}

To append an element to a specific element by DOM , we can use these code:

　　//1.create an element first

　　Element element = document.createElement("element‘s name");

　　//2.set the element‘s text content

　　element.setTextContent("element‘s content text");

　　//3.set the element as the child element and append this child element to the parent element.

　　parentElement.appendChild(element);