Java-xpath Learning

/**

• Use XPath technology to get content under any level in an XML file DOM4J-based XPath technology
• 1) Ability to quickly locate required elements in an XML file without navigating from one of the root elements to the desired child elements
• Document.selectnodes (): Get all XPath-compliant elements
• Document.selectsinglenode (): Gets the first element of all elements that conform to the XPath format
• Node type is element/text/attribute/document/... The parent interface of the type
• */

Import Java.io.file;import java.util.list;import Java.util.scanner;import Org.dom4j.document;import Org.dom4j.documentexception;import Org.dom4j.element;import Org.dom4j.io.saxcontenthandler;import Org.dom4j.io.saxreader;import org.junit.test;/** * Use XPath technology to get content under any level in the XML file based on dom4j XPath technology * 1) ability to quickly locate the required element in an XML file, No need to navigate from one to the root element to the desired child element * Document.selectnodes (): Get all XPath-compliant elements * Document.selectsinglenode () : Gets the first element of all XPath-compliant elements * node type is element/text/attribute/document/... Parent interface of type * */public class Xpath {@Test public void xpathtest () throws Exception {Saxreader reader = new Saxre        Ader ();        Document document = Reader.read (new File ("Src/day2/domx/car.xml"));        String XPath = "//Unit Price";        list<element> elementlist = Document.selectnodes (XPath);            for (Element e:elementlist) {System.out.println (E.gettext ());        System.out.println ("================="); }} @Test public void Xpathtest1 () throws Exception {Saxreader reader = new Saxreader ();        Document document = Reader.read (new File ("Src/day2/domx/car.xml"));        String XPath = "//Unit Price";        list<element> elementlist = Document.selectnodes (XPath);    System.out.println ("The price of the second car is:" + elementlist.get (1). GetText ());        } @Test public void Xpathtest2 () throws Exception {Saxreader reader = new Saxreader ();        Document document = Reader.read (new File ("Src/day2/domx/car.xml"));        String XPath = "//Unit Price";        element element = (Element) Document.selectsinglenode (XPath);    System.out.println ("The price of the first car is:" + element.gettext ()); } @Test public void login () throws Exception {//reads the user's input information on the keyboard Scanner Scanner = new Scanner (system.in        );        System.out.println ("User name:");        String username = Scanner.nextline ();        System.out.print ("Password:");        String password = scanner.nextline ();        System.out.println (username+ ":" +password); Parses the XML file and queries the specified element Saxreader SaxreaDer = new Saxreader ();        Document document = Saxreader.read (new File ("Src/day2/domx/users.xml"));        String XPath = "//user[@username = '" +username+ "' and @password = '" +password+ "']";        element element = (Element) Document.selectsinglenode (XPath);        if (element! = null) {System.out.println ("login succeeded");        }else {System.out.println ("Login Failed"); }    }}

User.xml

<?xml version="1.0" encoding="UTF-8"?><root>   <user id = "id001" username ="liwen" password="123456"></user>   <user id = "id002" username ="python" password="23456"></user></root>

Results:
User name:
Liwen
Password: 123456
Landing success

Java-xpath Learning