XpathByDom

package com.tudou.ajax.t1; import java.io.File; import java.io.IOException; import java.util.Iterator; import java.util.List; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpression; import javax.xml.xpath.XPathExpressionException; import javax.xml.xpath.XPathFactory; import org.w3c.dom.Document; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; public class XpathByDom { public static void main(String[] args) { XpathByDom xj = new XpathByDom(); xj.calByXpathExpression(); } /** * 通过Xpath表达式计算员工平均工资 */ public void calByXpathExpression() { try { File f = new File("WebRoot/xmls/employee.xml"); DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder; builder = factory.newDocumentBuilder(); Document doc = builder.parse(f); XPathFactory pathFactory = XPathFactory.newInstance(); XPath xpath = pathFactory.newXPath(); XPathExpression expre = xpath.compile("descendant::employee"); NodeList result = (NodeList) expre.evaluate(doc,XPathConstants.NODESET); System.out.println("共有员工：" + result.getLength()); for (int i = 0; i < result.getLength(); i++) { System.out.print("员工："+ result.item(i).getChildNodes().item(1).getTextContent()); System.out.println("，工资："+ result.item(i).getChildNodes().item(11).getTextContent()); } XPathExpression expre1 = xpath.compile("sum(//employee/salary) div count(descendant::employee)"); Object result1 = expre1.evaluate(doc,XPathConstants.NUMBER); System.out.println("----------------------"); System.out.println("平均工资："+result1); //销售额大于300000的工资有：公式为： "//sales[sale>300000" // System.out.println("销售额大于" + num + "的员工有：" + e1.getText() // + "，销售额为：" + e.getChild("sale").getText()); } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (XPathExpressionException e) { e.printStackTrace(); } } }

<?xml version="1.0" encoding="UTF-8"?>
<employees>
<employee id="scce001">
<name>Lan</name>
<dept>G3T05</dept>
<sex>famale</sex>
<birthday>
<year>1990</year>
<month>01</month>
<day>21</day>
</birthday>
<sales>
<year>2011</year>
<month>01</month>
<sale>70000</sale>
</sales>
<salary>3000</salary>
</employee>
<employee id="scce002">
<name>TuDou</name>
<dept>G3T05</dept>
<sex>male</sex>
<birthday>
<year>1989</year>
<month>01</month>
<day>24</day>
</birthday>
<sales>
<year>2011</year>
<month>01</month>
<sale>394000</sale>
</sales>
<salary>10000</salary>
</employee>
<employee id="scce003">
<name>Lee</name>
<dept>G3T05</dept>
<sex>male</sex>
<birthday>
<year>1989</year>
<month>09</month>
<day>03</day>
</birthday>
<sales>
<year>2011</year>
<month>01</month>
<sale>188880</sale>
</sales>
<salary>6000</salary>
</employee>
</employees>