Java--xml file Read (DOM)

1, performance: a ". xml" file with an extension

2. Storage: Tree-shaped structure

3. XML parsing application:

Communication between different applications-booking software and payment software

Communication between different platforms--operating system

Sharing data between different platforms--websites and mobile phones

4.

The process of reading an XML file in a Java program is also known as parsing an XML file

Purpose of parsing: Get node name, node value, property name, property value

Parsing methods: DOM, SAX, dom4j, JDOM

5, pre-resolution preparation work:

 Packagecom.imooc_xml.dom.test;Importjava.io.IOException;ImportJavax.xml.parsers.DocumentBuilder;Importjavax.xml.parsers.DocumentBuilderFactory;Importjavax.xml.parsers.ParserConfigurationException;Importorg.w3c.dom.Document;ImportOrg.w3c.dom.NamedNodeMap;ImportOrg.w3c.dom.Node;Importorg.w3c.dom.NodeList;Importorg.xml.sax.SAXException; Public classDomtest { Public Static voidMain (string[] args) {//1. Create a Documentbuilderfactory objectDocumentbuilderfactory DBF =documentbuilderfactory.newinstance (); //2. Create a Documentbuilder object        Try{Documentbuilder db=Dbf.newdocumentbuilder (); //loading an XML file into the current project through the parser method of the Documentbuilder objectDocument document = Db.parse ("Xml/books.xml");             }                    } Catch(parserconfigurationexception e) {e.printstacktrace (); } Catch(saxexception e) {e.printstacktrace (); } Catch(IOException e) {e.printstacktrace (); }    }}

6. Parse the attribute name and attribute value of the XML file:

NodeList Booklist = document.getElementsByTagName ("book"); //traverse each book nodeSystem.out.println ("A total of" +booklist.getlength () + "book");  for(intI=0;i<booklist.getlength (); i++) {Node Book=Booklist.item (i); //traversing the properties of a bookNamedNodeMap attrs =book.getattributes (); System.out.println ("I+1" + "book in total" +attrs.getlength () + "Properties");  for(intJ=0;j<attrs.getlength (); j + +) {Node attr=Attrs.item (j); System.out.println ("Property Name:" +attr.getnodename ()); System.out.println ("Attribute value:" +Attr.getnodevalue ()); }                /*** If you already know that the book node has and can only have one ID attribute * Element book = Booklist.item (i);                 * String AttrValue = book.getattribute ("id"); */

7. Parse the node name and node value of the XML file:

NodeList childNodes =book.getchildnodes (); System.out.println ("First" + (i+1) + "book Total" +childnodes.getlength ()+ "Child Nodes");  for(intK = 0;k<childnodes.getlength (); k++){                    //The text type of node (with line breaks and spaces) and the element type of node                    if(Childnodes.item (k). Getnodetype () = =Node.element_node)                        {System.out.println (Childnodes.item (k). Getnodename ()); //Gets the node value of element type element type node//getfirstchild (). Getnodevalue (): considers the value to be a child of a child node//System.out.println (Childnodes.item (k). Getfirstchild (). Getnodevalue ()); //difference: <name><a>aa</a>java programming idea </name> one is null, one is Aajava programming thoughtSystem.out.println (Childnodes.item (k). Gettextcontent ()); }                }

8. Common node types:

Java--xml file Read (DOM)