java通过XPath解析xml节点的代码详解
16lz
2021-01-22
import java.io.File;import java.io.FileInputStream; import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.xpath.XPath;import javax.xml.xpath.XPathConstants;import javax.xml.xpath.XPathFactory; import org.w3c.dom.Document;import org.w3c.dom.Node;import org.w3c.dom.NodeList; public class FindElementsByAbsoluteLocationWithXPath { public static void main(String[] args) throws Exception { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); dbf.setValidating(false); DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse(new FileInputStream(new File("in.xml"))); XPathFactory factory = XPathFactory.newInstance(); XPath xpath = factory.newXPath(); String expression; Node node; NodeList nodeList; // 1. root element expression = "/*"; node = (Node) xpath.evaluate(expression, doc, XPathConstants.NODE); System.out.println("1. " + node.getNodeName()); // 2. root element (by name) expression = "/rss"; node = (Node) xpath.evaluate(expression, doc, XPathConstants.NODE); System.out.println("2. " + node.getNodeName()); // 3. element under rss expression = "/rss/channel"; node = (Node) xpath.evaluate(expression, doc, XPathConstants.NODE); System.out.println("3. " + node.getNodeName()); // 4. all elements under rss/channel expression = "/rss/channel/*"; nodeList = (NodeList) xpath.evaluate(expression, doc, XPathConstants.NODESET); System.out.print("4. "); for (int i = 0; i < nodeList.getLength(); i++) { System.out.print(nodeList.item(i).getNodeName() + " "); } System.out.println(); // 5. all title elements in the document expression = "//title"; nodeList = (NodeList) xpath.evaluate(expression, doc, XPathConstants.NODESET); System.out.print("5. "); for (int i = 0; i < nodeList.getLength(); i++) { System.out.print(nodeList.item(i).getNodeName() + " "); } System.out.println(); // 6. all elements in the document except title expression = "//*[name() != 'title']"; nodeList = (NodeList) xpath.evaluate(expression, doc, XPathConstants.NODESET); System.out.print("6. "); for (int i = 0; i < nodeList.getLength(); i++) { System.out.print(nodeList.item(i).getNodeName() + " "); } System.out.println(); // 7. all elements with at least one child element expression = "//*[*]"; nodeList = (NodeList) xpath.evaluate(expression, doc, XPathConstants.NODESET); System.out.print("7. "); for (int i = 0; i < nodeList.getLength(); i++) { System.out.print(nodeList.item(i).getNodeName() + " "); } System.out.println(); // 8. all level-5 elements (the root being at level 1) expression = "/*/*/*/*"; nodeList = (NodeList) xpath.evaluate(expression, doc, XPathConstants.NODESET); System.out.print("8. "); for (int i = 0; i < nodeList.getLength(); i++) { System.out.print(nodeList.item(i).getNodeName() + " "); } System.out.println(); } }
Input:
<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"> <channel> <title>Java Tutorials and Examples 2</title> <language>en-us</language> <item> <title><![CDATA[Java Tutorials 2]]></title> <link>http://www.javacodegeeks.com/</link> </item> <item> <title><![CDATA[Java Examples 2]]></title> <link>http://examples.javacodegeeks.com/</link> </item> </channel></rss>
输出:
1. rss2. rss3. channel4. title language item item5. title title title6. rss channel language item link item link7. rss channel item item8. title link title link
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