Example analysis of using DOM to parse xml in java

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 a parser factory instance and generate a parser
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
//Create the document object that needs to be parsed
File f = new File("books.xml");
//Parse the document and return a Document object. At this time, the xml document has been loaded into memory.
//Okay, let's make the parsing more intense, and the rest is to get the data.
Document doc = builder.parse(f);

//Get the document root element
//You ask me why I do this? Because the document object itself is a tree structure, and this is the root of the tree.
//Of course, you can also find the element collection directly and omit this step
Element root = doc.getDocumentElement();

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

for (int i = 0; i < list.getLength(); i++) {
//Find the node in the collection through the item() method, and convert it down to an Element object
Element n = (Element) list.item(i);
//Get the attribute map in the object, use a for loop to extract and print
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 complicated, 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();
}
}

}