Sample analysis of XML parsing using dom in Java

Dom is a powerful parsing tool for small documents

Why do you say that? Because it loads the entire XML document into memory, forming a document object tree

It sounds scary in general, but it's a lot easier than Sax to use it to read small points

As for its addition and deletion operations, I am not going to write, I was almost ugly to vomit the code when I read the tutorial

That's why later tools like jdom and dom4j existed...

Without further ado, go straight to the code

Dom parsing example

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

 
public class Demo {

    public static void main(String[] args) throws Exception {
        //Create the parser factory instance and generate the parser
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        //Create a document object that needs to be parsed
        File f = new File("books.xml");
        //Parse the Document and return a Document object, at which point the XML Document is loaded into memory
        //Well, let the parsing get a little more intense, and the rest is just getting the data
        Document doc = builder.parse(f);

        //Gets the document root element
        //Why did I do that? Because the document object itself is a tree structure, this is the root
        //Of course, you can also go straight to the set of elements and skip this step
        Element root = doc.getDocumentElement();

        //The root node is found above, and here we begin to get the collection of elements under the root node
        NodeList list = root.getElementsByTagName("book");

        for (int i = 0; i < list.getLength(); i++) {
            //The item() method finds the node in the collection and transitions down to an Element object
            Element n = (Element) list.item(i);
            //Gets the property map in the object, extracts it with a for loop, and prints it
            NamedNodeMap node = n.getAttributes();
            for (int x = 0; x < node.getLength(); x++) {
                Node nn = node.item(x);
                System.out.println(nn.getNodeName() + ": " + nn.getNodeValue());
            }
            //Print element content, the code is very tangled, almost a fixed format
            System.out.println("title: " +n.getElementsByTagName("title").item(0).getFirstChild().getNodeValue());
            System.out.println("author: " + n.getElementsByTagName("author").item(0).getFirstChild().getNodeValue());
            System.out.println();
        }
    }

}

  Output results:

< img Alt = "" border = 0 SRC =" / / files.jb51.net/file_images/article/201305/20130503192138100.png ">