Question

如果这是重复的话，请道歉。我想显示Employees的所有子属性这是我的xml

<?xml version="1.0"?>
<Employees>
    <Employee emplid="1111" type="admin">
        <firstname>John</firstname>
        <lastname>Watson</lastname>
        <age>30</age>
        <email>johnwatson@sh.com</email>
    </Employee>
    <Employee emplid="2222" type="admin">
        <firstname>Sherlock</firstname>
        <lastname>Homes</lastname>
        <age>32</age>
        <email>sherlock@sh.com</email>
    </Employee>
    <Employee emplid="3333" type="user">
        <firstname>Jim</firstname>
        <lastname>Moriarty</lastname>
        <age>52</age>
        <email>jim@sh.com</email>
    </Employee>
    <Employee emplid="4444" type="user">
        <firstname>Mycroft</firstname>
        <lastname>Holmes</lastname>
        <age>41</age>
        <email>mycroft@sh.com</email>
    </Employee>
</Employees>

这是java类

package com.logic.xpath;
import java.io.FileInputStream;

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.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class Xpath 
{

    public static void main(String[] args) 
    {

        try
        {

            DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = builderFactory.newDocumentBuilder();
            Document document = builder.parse( new FileInputStream("c:\\file.xml"));

            /*String xml = ...;
            Document xmlDocument = builder.parse(new ByteArrayInputStream(xml.getBytes()));*/

            XPath xPath = XPathFactory.newInstance().newXPath();




//          Print all the employee email whose empid='3333'

            String expression = "/Employees/Employee[@emplid='3333']/email";
            System.out.println(expression);
            NodeList nodeList = (NodeList) xPath.compile(expression).evaluate(document, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) 
            {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

            // Pritnt all the employees firstname
            String expression1 = "/Employees/Employee/firstname";
            System.out.println(expression1);
             nodeList = (NodeList) xPath.compile(expression1).evaluate(document, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) 
            {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

            //Print all the employyees whose emp id is 2222
            String expression3 = "/Employees/Employee[@emplid='2222']";
            System.out.println(expression3);
            Node node = (Node) xPath.compile(expression3).evaluate(document, XPathConstants.NODE);
            if(null != node) {
                nodeList = node.getChildNodes();
                for (int i = 0;null!=nodeList && i < nodeList.getLength(); i++) {
                    Node nod = nodeList.item(i);
                    if(nod.getNodeType() == Node.ELEMENT_NODE)
                        System.out.println(nodeList.item(i).getNodeName() + " : " + nod.getFirstChild().getNodeValue());
                }
            }


            //Print all the employes firstname whose type is ADMIN

            String expression4 = "/Employees/Employee[@type='admin']/firstname";
            System.out.println(expression4);
             nodeList = (NodeList) xPath.compile(expression4).evaluate(document, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }


            //print all employees firstname whoes age is greater than 30
            String expression5 = "/Employees/Employee[age>40]/firstname";
            nodeList = (NodeList) xPath.compile(expression5).evaluate(document, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }


            //print first name of first 2 employee define in the respective element 

            String expression6 = "/Employees/Employee[position() <= 2]/firstname";
             nodeList = (NodeList) xPath.compile(expression6).evaluate(document, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }

    }

}

我想要display firstname lastname age email

像String expression1 = "/Employees/Employee/firstname";一样，只打印员工的名字，如何打印每件事

预期产出：

 firstname=John lastname=Watson age=30 email=johnwatson@sh.com firstname=Sherlock lastname=Homes age=32 email=sherlock@sh.com and so on of every employee

Answer 1

您可以尝试使用像

这样的StAX方法

private final static String xml = <<your big xml>>;

public static void main(String... args) throws XMLStreamException {
    // flag to indicate processing of Employee tag
    boolean isEmployee = false;
    // Flag to indicate processing text data in a tag rather than whitespaces outside tags, 
    // e.g. spaces between brackets
    // <Employee emplid="3333" type="user">[
    //        ]<firstname>Jim</firstname>
    boolean showText = false;
    // current tag name;
    String tagName = "";
    XMLInputFactory xif = XMLInputFactory.newFactory();
    XMLEventReader reader = xif.createXMLEventReader(new StringReader(xml));
    while (reader.hasNext()) {
        XMLEvent ev = reader.nextEvent();
        switch (ev.getEventType()) {
        case START_ELEMENT:
            StartElement start = ev.asStartElement();
            tagName = start.getName().getLocalPart();
            if (tagName.equalsIgnoreCase("Employee")) {
                isEmployee = true;
            } else if (isEmployee) {
                showText = true;
            }
            break;
        case CHARACTERS:
            Characters chars = ev.asCharacters();
            if (isEmployee && showText) {
                System.out.println(tagName + " = " + chars.getData());
            }
            break;
        case END_ELEMENT:
            EndElement end = ev.asEndElement();
            if (end.getName().getLocalPart().equalsIgnoreCase("Employee")) {
                isEmployee = false;
                System.out.println("");
            }
            showText = false;
            break;
        }
    }
}

它需要Java 6+，可以从JavaDoc和Oracle

获得更多帮助

Answer 2

请尝试使用这些Xpath获取每个字段的单独值，保存任何变量以形成整个输出

//Employee[@emplid]/firstname/text()
//Employee[@emplid]/lastname/text()
//Employee[@emplid]/age/text()
//Employee[@emplid]/email/text()

要在xpath

下面使用所有文本

//Employee[@emplid]//text()

Answer 3

我找到了打印所有子元素的解决方案。

我只是改变了表达式

String expression1 = "/Employees/Employee/*";
            System.out.println(expression1);
             nodeList = (NodeList) xPath.compile(expression1).evaluate(document, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) 
            {
                System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
            }

添加*让我的工作

如何使用XPATH

3 个答案: