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This article mainly introduces XML, JAXP technology and DOM parsing example analysis, the article is very detailed, has a certain reference value, interested friends must read it!

The basic idea of DOM parsing:

1. Read the whole XML file into memory at one time

2. Think of the whole XML as a tree

3. Every tag, attribute, and text in XML is regarded as a node on the tree.

4. Then you can add, delete, modify and check the nodes.

Put the code on.

1. First of all, I created a new text file in D:\ ABC and renamed it to stus.xml. Here's what's in the file.

Zhang San 20 male Li Si 21 female Wang Wu 22 male

In the first line is the XML declaration, version represents the version number, encoding represents the encoding method, Microsoft notepad uses the national standard encoding method, if you want to use UTF-8, then modify the encoding mode to UTF-8 in the Save as window.

Must and can only have a pair of root tags, and the root tag I wrote is. I won't say much about the rest.

2. This is a student class that defines some properties and get, set methods

Public class Student {public static String Class; private String name; private int num; private int age; private char sex; public String getName () {return name;} public void setName (String name) {this.name = name;} public int getNum () {return num } public void setNum (int num) {this.num = num;} public int getAge () {return age;} public void setAge (int age) {this.age = age;} public char getSex () {return sex } public void setSex (char sex) {this.sex = sex;}}

3. This is a class parsed with DOM, and you need to know about it before you look at it.

DocumentBuilderFactory DOM parser factory

DocumentBuilder DOM parser

Document document object

Node node [interface]

Element element node [label node]

Attr attribute node

Text text node

Node is the parent interface of Document,Element,Attr,Text

List of NodeList nodes

NamedNodeMap all attributes of a node

Import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import org.w3c.dom.Attr;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;import bean.Student Public class DOMParser {public static void main (String [] args) throws Exception {/ / get the parser factory object DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance (); / / produce a parser object DocumentBuilder builder = factory.newDocumentBuilder () / / start parsing the XML file and get the result of parsing, which is a Document object / / Document object called document tree object Document dom = builder.parse ("D:\\ ABC\\ stus.xml") / / extract data through the Document object / / the first child node of the Document object is the root node [root tag] Node root = dom.getFirstChild (); / / get the name of the tag String str = root.getNodeName () / / get the attribute of the root node NamedNodeMap attrs = root.getAttributes (); / / strongly convert to the Attr type attribute class Attr attr = (Attr) attrs.getNamedItem ("class"); / / get the value in the attribute String v = attr.getValue (); System.out.println (v) / / get all the students-- NodeList list = root.getChildNodes (); for (int I = 0; I < list.getLength (); iTunes +) {Node node = list.item (I) / / determine whether it is a tag node if (node instanceof Element) {Element e = (Element) node; / / get the value of the attribute in the tag node String num = e.getAttribute ("num") System.out.println (num); / / output the text in the tag / / System.out.println (e.getTextContent ()) / / continue to get the child nodes of stu NodeList nodeList = e.getChildNodes (); for (int j = 0; j < nodeList.getLength (); jacks +) {Node n = nodeList.item (j) If (n instanceof Element) {Element ele = (Element) n; / / get the tag name of the element node String nodeName = ele.getNodeName () / / get the text String value = ele.getTextContent () in the element node tag If (nodeName.equals ("name")) {System.out.println ("name:" + value) } else if (nodeName.equals ("age")) {System.out.println ("Age:" + value) } else if (nodeName.equals ("sex")) {System.out.println ("gender:" + value) }}}

I have summarized some methods in it:

DocumentBuilderFactory class:

Public static DocumentBuilderFactory newInstance (); / / get the parser factory object public abstract DocumentBuilder newDocumentBuilder (); / / produce a parser object

DocumentBuilder class:

Public Document parse (String uri); / / parse the XML file whose path is uri, and the result is a Document object.

Node class:

Public Node getFirstChild (); / / get the first child node of the Document object, that is, the root node, or root tag. What you get in the above code is stus. Look at the contents of the XML file in point 1 above. Public NamedNodeMap getAttributes (); / / get the attribute public NodeList getChildNodes () of the node; / / get all the child nodes public String getNodeName (); / / get the name of the tag public String getTextContent () throws DOMException;// get the text in the tag node

NamedNodeMap class:

Public Node getNamedItem (String name); / / returns all nodes named name

Attr class:

Public String getValue (); / / get the value in the attribute

NodeList class:

Public Node item (int index); / / returns the index node

Element class:

Public String getAttribute (String name); / / get the value of the attribute name in the tag node. The above is all the content of the article "sample Analysis of XML, JAXP Technology and DOM parsing". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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