JAVA与DOM解析器提高（DOM/SAX/JDOM/DOM4j/XPath） 学习笔记二

要求

• 必备知识

  JAVA基础知识。XML基础知识。

• 开发环境

  MyEclipse10

• 资料下载

  源码下载

 

sax、dom是两种对xml文档进行解析的方法(没有具体实现，只是接口)，所以只有它们是无法解析xml文档的；jaxp只是api，它进一步封装了sax、dom两种接口，并且提供了DomcumentBuilderFactory/DomcumentBuilder和SAXParserFactory/SAXParser（默认使用xerces解释器）。

如对DOM解析器还有疑问,请查看这里。目前在Java中用于解析XML的技术很多，主流的有DOM、SAX、JDOM、DOM4j,下面分别介绍这四种方式如何操作DOM。

university.xml

<?xml version="1.0" encoding="UTF-8"?>
<university name="pku">
    <college name="c1">
        <class name="class1">
            <student name="stu1" sex='male' age="21" />
            <student name="stu2" sex='female' age="20" />
            <student name="stu3" sex='female' age="20" />
        </class>
        <class name="class2">
            <student name="stu4" sex='male' age="19" />
            <student name="stu5" sex='female' age="20" />
            <student name="stu6" sex='female' age="21" />
        </class>
    </college>
    <college name="c2">
        <class name="class3">
            <student name="stu7" sex='male' age="20" />
        </class>
    </college>
    <college name="c3">
    </college>
</university>

dom读写xml 输出属性值,此方法我已经到上篇随笔中有详细介绍了,点这里查看.

TestDom.java

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.SAXException;

/**
 * dom读写xml 输出属性值
 * @author whwang
 */
public class TestDom {
    
   
    
    public static void read() {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {
            DocumentBuilder builder = dbf.newDocumentBuilder();
            InputStream in = TestDom.class.getClassLoader().getResourceAsStream("university.xml"); //读取src目录下文件
            Document doc = builder.parse(in);
           
            Element root = doc.getDocumentElement(); // 获取根元素
            if (root == null) return;
            System.err.println(root.getAttribute("name")); //获取根元素的name属性值
            
            NodeList collegeNodes = root.getChildNodes();// 根元素下的所有子元素
            if (collegeNodes == null) return;
            
            /**
             * 循环所有的根元素下的所有只节点
             * 根元素下所有的college 节点
             */
            for(int i = 0; i < collegeNodes.getLength(); i++) {
                Node college = collegeNodes.item(i);
                if (college != null && college.getNodeType() == Node.ELEMENT_NODE) {
                    System.err.println("	" + college.getAttributes().getNamedItem("name").getNodeValue()); //获取节点 name属性值
                    // 所有的class节点
                    NodeList classNodes = college.getChildNodes();
                    if (classNodes == null) continue;
                    for (int j = 0; j < classNodes.getLength(); j++) {
                        Node clazz = classNodes.item(j);
                        if (clazz != null && clazz.getNodeType() == Node.ELEMENT_NODE) {
                            System.err.println("		" + clazz.getAttributes().getNamedItem("name").getNodeValue());
                            // 所有的student节点
                            NodeList studentNodes = clazz.getChildNodes();
                            if (studentNodes == null) continue;
                            for (int k = 0; k < studentNodes.getLength(); k++) {
                                Node student = studentNodes.item(k);
                                if (student != null && student.getNodeType() == Node.ELEMENT_NODE) {
                                    System.err.print("			" + student.getAttributes().getNamedItem("name").getNodeValue());
                                    System.err.print(" " + student.getAttributes().getNamedItem("sex").getNodeValue());
                                    System.err.println(" " + student.getAttributes().getNamedItem("age").getNodeValue());
                                }
                            }
                        }
                    }
                }
            }
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }
    
    
    
    
    /**
     * 读取本地XML文件 修改后另存为
     */
    public static void write() {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {
            DocumentBuilder builder = dbf.newDocumentBuilder();
            InputStream in = TestDom.class.getClassLoader().getResourceAsStream("university.xml");
            Document doc = builder.parse(in);
            // 根节点
            Element root = doc.getDocumentElement();
            if (root == null) return;
            // 修改属性
            root.setAttribute("name", "tsu"); //给根元素添加 name属性和属性值
            NodeList collegeNodes = root.getChildNodes();
            if (collegeNodes != null) {
                for (int i = 0; i <collegeNodes.getLength() - 1; i++) {
                    // 删除节点
                    Node college = collegeNodes.item(i);
                    if (college.getNodeType() == Node.ELEMENT_NODE) {
                        String collegeName = college.getAttributes().getNamedItem("name").getNodeValue();
                        if ("c1".equals(collegeName) || "c2".equals(collegeName)) {
                            root.removeChild(college);
                        } else if ("c3".equals(collegeName)) {
                            Element newChild = doc.createElement("class");
                            newChild.setAttribute("name", "c4");
                            college.appendChild(newChild);
                        }
                    }
                }
            }
            // 新增节点
            Element addCollege = doc.createElement("college");
            addCollege.setAttribute("name", "c5");
            root.appendChild(addCollege);
            Text text = doc.createTextNode("text");
            addCollege.appendChild(text);
            
            // 将修改后的文档保存到文件
            TransformerFactory transFactory = TransformerFactory.newInstance();
            Transformer transFormer = transFactory.newTransformer();
            DOMSource domSource = new DOMSource(doc);
            File file = new File("src/dom-modify.xml");
            if (file.exists()) {
                file.delete();
            }
            file.createNewFile();
            FileOutputStream out = new FileOutputStream(file);         
            StreamResult xmlResult = new StreamResult(out);
            transFormer.transform(domSource, xmlResult);
            System.out.println(file.getAbsolutePath());  //获取文件的据对路径
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (TransformerConfigurationException e) {
            e.printStackTrace();
        } catch (TransformerException e) {
            e.printStackTrace();
        }
    }
    
    
    public static void main(String[] args) {
        read();
        //write();
    }
}

SAX不用将整个文档加载到内存，基于事件驱动的API(Observer模式)，用户只需要注册自己感兴趣的事件即可。SAX提供EntityResolver, DTDHandler, ContentHandler, ErrorHandler接口，分别用于监听解析实体事件、DTD处理事件、正文处理事件和处理出错事件，与AWT类似，SAX还提供了一个对这4个接口默认的类DefaultHandler（这里的默认实现，其实就是一个空方法），一般只要继承DefaultHandler.

TestSAX.java

import java.io.IOException;
import java.io.InputStream;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.helpers.DefaultHandler;

/**
 *
 * @author whwang
 */
public class TestSAX {

    public static void main(String[] args) {
        read();
        write();
    }
    
    public static void read() {
        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser parser = factory.newSAXParser();
            InputStream in = TestSAX.class.getClassLoader().getResourceAsStream("university.xml");
            parser.parse(in, new MyHandler());
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public static void write() {
        System.err.println("纯SAX对于写操作无能为力");
    }
    
}

// 重写对自己感兴趣的事件处理方法
class MyHandler extends DefaultHandler {

    @Override
    public InputSource resolveEntity(String publicId, String systemId)
            throws IOException, SAXException {
        return super.resolveEntity(publicId, systemId);
    }

    @Override
    public void notationDecl(String name, String publicId, String systemId)
            throws SAXException {
        super.notationDecl(name, publicId, systemId);
    }

    @Override
    public void unparsedEntityDecl(String name, String publicId,
            String systemId, String notationName) throws SAXException {
        super.unparsedEntityDecl(name, publicId, systemId, notationName);
    }

    @Override
    public void setDocumentLocator(Locator locator) {
        super.setDocumentLocator(locator);
    }

    @Override
    public void startDocument() throws SAXException {
        System.err.println("开始解析文档");
    }

    @Override
    public void endDocument() throws SAXException {
        System.err.println("解析结束");
    }

    @Override
    public void startPrefixMapping(String prefix, String uri)
            throws SAXException {
        super.startPrefixMapping(prefix, uri);
    }

    @Override
    public void endPrefixMapping(String prefix) throws SAXException {
        super.endPrefixMapping(prefix);
    }

    @Override
    public void startElement(String uri, String localName, String qName,
            Attributes attributes) throws SAXException {
        System.err.print("Element: " + qName + ", attr: ");
        print(attributes);
    }

    @Override
    public void endElement(String uri, String localName, String qName)
            throws SAXException {
        super.endElement(uri, localName, qName);
    }

    @Override
    public void characters(char[] ch, int start, int length)
            throws SAXException {
        super.characters(ch, start, length);
    }

    @Override
    public void ignorableWhitespace(char[] ch, int start, int length)
            throws SAXException {
        super.ignorableWhitespace(ch, start, length);
    }

    @Override
    public void processingInstruction(String target, String data)
            throws SAXException {
        super.processingInstruction(target, data);
    }

    @Override
    public void skippedEntity(String name) throws SAXException {
        super.skippedEntity(name);
    }

    @Override
    public void warning(SAXParseException e) throws SAXException {
        super.warning(e);
    }

    @Override
    public void error(SAXParseException e) throws SAXException {
        super.error(e);
    }

    @Override
    public void fatalError(SAXParseException e) throws SAXException {
        super.fatalError(e);
    }
    
    private void print(Attributes attrs) {
        if (attrs == null) return;
        System.err.print("[");
        for (int i = 0; i < attrs.getLength(); i++) {
            System.err.print(attrs.getQName(i) + " = " + attrs.getValue(i));
            if (i != attrs.getLength() - 1) {
                System.err.print(", ");
            }
        }
        System.err.println("]");
    }
}

JDOM与DOM非常类似，它是处理XML的纯JAVA API，API大量使用了Collections类，且JDOM仅使用具体类而不使用接口。　JDOM 它自身不包含解析器。它通常使用 SAX2 解析器来解析和验证输入 XML 文档（尽管它还可以将以前构造的 DOM 表示作为输入）。它包含一些转换器以将 JDOM 表示输出成 SAX2 事件流、DOM 模型或 XML 文本文档。

TestJDom.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.jdom.Attribute;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;

/**
 * JDom读写xml
 * @author whwang
 */
public class TestJDom {
    public static void main(String[] args) {
       read();
        write();
    }
    
    public static void read() {
        try {
            boolean validate = false;
            SAXBuilder builder = new SAXBuilder(validate);
            InputStream in = TestJDom.class.getClassLoader().getResourceAsStream("university.xml");
            Document doc = builder.build(in);
            // 获取根节点 <university>
            Element root = doc.getRootElement();
            readNode(root, "");
        } catch (JDOMException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    @SuppressWarnings("unchecked")
    public static void readNode(Element root, String prefix) {
        if (root == null) return;
        // 获取属性
        List<Attribute> attrs = root.getAttributes();
        if (attrs != null && attrs.size() > 0) {
            System.err.print(prefix);
            for (Attribute attr : attrs) {
                System.err.print(attr.getValue() + " ");
            }
            System.err.println();
        }
        // 获取他的子节点
        List<Element> childNodes = root.getChildren();
        prefix += "	";
        for (Element e : childNodes) {
            readNode(e, prefix);
        }
    }
    
    public static void write() {
        boolean validate = false;
        try {
            SAXBuilder builder = new SAXBuilder(validate);
            InputStream in = TestJDom.class.getClassLoader().getResourceAsStream("university.xml");
            Document doc = builder.build(in);
            // 获取根节点 <university>
            Element root = doc.getRootElement();
            // 修改属性
            root.setAttribute("name", "tsu");
            // 删除
            boolean isRemoved = root.removeChildren("college");
            System.err.println(isRemoved);
            // 新增
            Element newCollege = new Element("college");
            newCollege.setAttribute("name", "new_college");
            Element newClass = new Element("class");
            newClass.setAttribute("name", "ccccc");
            newCollege.addContent(newClass);
            root.addContent(newCollege);
            XMLOutputter out = new XMLOutputter();
            File file = new File("src/jdom-modify.xml");
            if (file.exists()) {
                file.delete();
            }
            file.createNewFile();
            FileOutputStream fos = new FileOutputStream(file);
            out.output(doc, fos);
        } catch (JDOMException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
}

dom4j是目前在xml解析方面是最优秀的(Hibernate、Sun的JAXM也都使用dom4j来解析XML)，它合并了许多超出基本 XML 文档表示的功能，包括集成的 XPath 支持、XML Schema 支持以及用于大文档或流化文档的基于事件的处理

TestDom4j.java

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.ProcessingInstruction;
import org.dom4j.VisitorSupport;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

/**
 * Dom4j读写xml
 * @author whwang
 */
public class TestDom4j {
    public static void main(String[] args) {
        read1();
       // read2();
       write();
    }

    public static void read1() {
        try {
            SAXReader reader = new SAXReader();
            InputStream in = TestDom4j.class.getClassLoader().getResourceAsStream("university.xml");
            Document doc = reader.read(in);
            Element root = doc.getRootElement();
            readNode(root, "");
        } catch (DocumentException e) {
            e.printStackTrace();
        }
    }
    
    @SuppressWarnings("unchecked")
    public static void readNode(Element root, String prefix) {
        if (root == null) return;
        // 获取节点的属性
        List<Attribute> attrs = root.attributes();
        if (attrs != null && attrs.size() > 0) {
            System.err.print(prefix);
            for (Attribute attr : attrs) {
                System.err.print(attr.getValue() + " ");
            }
            System.err.println();
        }
        // 获取他的子节点
        List<Element> childNodes = root.elements();
        prefix += "	";
        for (Element e : childNodes) {
            readNode(e, prefix);
        }
    }
    
    public static void read2() {
        try {
            SAXReader reader = new SAXReader();
            InputStream in = TestDom4j.class.getClassLoader().getResourceAsStream("university.xml");
            Document doc = reader.read(in);
            doc.accept(new MyVistor());
        } catch (DocumentException e) {
            e.printStackTrace();
        }
    }
    
    
    
    /**
     * 写入方法
     */
    public static void write() {
        try {
            // 创建一个xml文档
            Document doc = DocumentHelper.createDocument();
            Element university = doc.addElement("university");
            university.addAttribute("name", "tsu");
            // 注释
            university.addComment("这个是根节点");
            Element college = university.addElement("college");
            college.addAttribute("name", "cccccc");
            college.setText("text");
            
            File file = new File("src/dom4j-modify.xml");
            if (file.exists()) {
                file.delete();
            }
            file.createNewFile();
            XMLWriter out = new XMLWriter(new FileWriter(file));
            out.write(doc);
            out.flush();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class MyVistor extends VisitorSupport {
    public void visit(Attribute node) {
        System.out.println("Attibute: " + node.getName() + "="
                + node.getValue());
    }

    public void visit(Element node) {
        if (node.isTextOnly()) {
            System.out.println("Element: " + node.getName() + "="
                    + node.getText());
        } else {
            System.out.println(node.getName());
        }
    }

    @Override
    public void visit(ProcessingInstruction node) {
        System.out.println("PI:" + node.getTarget() + " " + node.getText());
    }
}

由于DOM4J比较重要我到网上还整理了一些代码:

Dom4j.java

import java.io.File;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.Iterator;
import java.util.List;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;






public class Dom4j {
    
    
    
    /**
     * 获取Document对象
     * 此方法文件位于 项目根目录 不是src目录
     * @param filename  项目根目录下的XML文件
     * @return  document 
     * 
     */
    public static Document load(String filename) {
        Document document = null;
        try {
            SAXReader saxReader = new SAXReader();
            document = saxReader.read(new File(filename));  //读取XML文件,获得document对象
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return document;
    }  
    
    
    /**
     * 通过url路径获取 Document对象
     * 此方式 xml文件位于远程服务器上
     * @param url 远程url文件
     * @return document对象
     */
    public static Document load2(URL url) {
        Document document = null;
        try {
            SAXReader saxReader = new SAXReader();
            document = saxReader.read(url);  //读取XML文件,获得document对象
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return document;

    }
    
    
    
    /**
     * 获取根节点
     * @param doc  document对象
     * @return 根元素
     */
    public static Element getRootElement(Document doc){
        Element root=null;
        root=doc.getRootElement(); //获取根节点
        return root;
        
    
    }
    
    
    
    

    
    
    /**
     * 将document树输出到指定的文件
     * @param document document对象
     * @param filename 文件名
     * @return 布尔值
     */
    public static boolean doc2XmlFile(Document document, String filename) {
        boolean flag = true;
        try {
            XMLWriter writer = new XMLWriter( new OutputStreamWriter(new FileOutputStream(filename),"UTF-8"));
            writer.write(document);
            writer.close();
        } catch (Exception ex) {
            flag = false;
            ex.printStackTrace();
        }
            System.out.println(flag);
            return flag;
        }
    
    
     
    
    /**
     * 
     * 
     * 此方法在本类中无用 ，没有整合 有兴趣的可以自己动手整合一下
     * 
     * 
     * Dom4j通过XMLWriter将Document对象表示的XML树写入指定的文件，
     * 并使用OutputFormat格式对象指定写入的风格和编码方法。
     * 调用OutputFormat.createPrettyPrint()方法可以获得一个默认的pretty print风格的格式对象。
     * 对OutputFormat对象调用setEncoding()方法可以指定XML文件的编码方法。
     * @param doc
     * @param out
     * @param encoding
     * @throws UnsupportedEncodingException
     * @throws IOException
     */
    /*public void writeTo(Document doc,OutputStream out, String encoding) throws UnsupportedEncodingException, IOException {
           OutputFormat format = OutputFormat.createPrettyPrint();
           format.setEncoding("gb2312");
           XMLWriter writer = new XMLWriter(System.out,format);
           writer.write(doc);
           writer.flush();
    }*/
    
    
    
    /**
     * 遍历根标记下的子元素
     * @param args
     */

    public static void read(Element root){    
        for(Iterator i=root.elementIterator();i.hasNext();){
            Element element=(Element)i.next();
            System.out.print(element.getName()+":"+element.getText());
            if(element.getNodeType()==Node.ELEMENT_NODE){
                read(element);
            }
        }

    }
    
    
    
    
    /**
     * 写入操作
     * @param fileName
     */
    public static void write(String fileName){
        
        Document document=DocumentHelper.createDocument();//建立document对象，用来操作xml文件
        Element booksElement=document.addElement("books");//建立根节点
        booksElement.addComment("This is a test for dom4j ");//加入一行注释
        Element bookElement=booksElement.addElement("book");//添加一个book节点
        bookElement.addAttribute("show","yes");//添加属性内容
        Element titleElement=bookElement.addElement("title");//添加文本节点
        titleElement.setText("ajax in action");//添加文本内容
        try{
            
            XMLWriter writer=new XMLWriter(new FileWriter(new File(fileName))); 
            writer.write(document);
            writer.close();
        }catch(Exception e){
            e.printStackTrace();
        }
    }
    
    
    
    
    
    
    /**
     * 修改XML文件
     */
    public static void modifyXMLFile() {
        String oldStr = "test.xml";
        String newStr = "test1.xml";
        Document document = null;
        //修改节点的属性
        try {
            SAXReader saxReader = new SAXReader(); // 用来读取xml文档
            document = saxReader.read(new File(oldStr)); // 读取xml文档
            List list = document.selectNodes("/books/book/@show");// 用xpath查找节点book的属性
            Iterator iter = list.iterator();
            while (iter.hasNext()) {
            Attribute attribute = (Attribute) iter.next();
            if (attribute.getValue().equals("yes"))
                attribute.setValue("no");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        //修改节点的内容
        try {
            SAXReader saxReader = new SAXReader(); // 用来读取xml文档
            document = saxReader.read(new File(oldStr)); // 读取xml文档
            List list = document.selectNodes("/books/book/title");// 用xpath查找节点book的内容
            Iterator iter = list.iterator();
            while (iter.hasNext()) {
            Element element = (Element) iter.next();
            element.setText("xxx");// 设置相应的内容
        }
        } catch (Exception e) {
            e.printStackTrace();
        }

        
        try {
            XMLWriter writer = new XMLWriter(new FileWriter(new File(newStr)));
            writer.write(document);
            writer.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
    
    
    
    
    
    
    
    
    
    
    public static void main(String[] args){
        Document doc=load("student.xml");
        Element root=getRootElement(doc);
        read(root);
    write("test.xml");
        modifyXMLFile();
    }
    
    
    
    

}

XPath 是一门在 XML 文档中查找信息的语言， 可用来在 XML 文档中对元素和属性进行遍历。XPath 是 W3C XSLT 标准的主要元素，并且 XQuery 和 XPointer 同时被构建于 XPath 表达之上。因此，对 XPath 的理解是很多高级 XML 应用的基础。
XPath非常类似对数据库操作的SQL语言，或者说JQuery，它可以方便开发者抓起文档中需要的东西。（dom4j也支持xpath, dom4j使用xpath请点击这里）

TestXPath.java

import java.io.IOException;
import java.io.InputStream;

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;



/**
 * 
 * 普通DOM与XPath
 * @author licheng
 *
 */
public class TestXPath {

    public static void main(String[] args) {
        read();
    }
    
    public static void read() {
        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = dbf.newDocumentBuilder();
            InputStream in = TestXPath.class.getClassLoader().getResourceAsStream("university.xml");
            Document doc = builder.parse(in);
            XPathFactory factory = XPathFactory.newInstance();
            XPath xpath = factory.newXPath();
            // 选取所有class元素的name属性
            // XPath语法介绍： http://w3school.com.cn/xpath/
            XPathExpression expr = xpath.compile("//class/@name");
            NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
            for (int i = 0; i < nodes.getLength(); i++) {
                System.out.println("name = " + nodes.item(i).getNodeValue());
                    }
        } catch (XPathExpressionException e) {
            e.printStackTrace();
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
}

不知为何，博客园每天只能到发表一篇随笔，发第二篇的时候不能到首页显示。

利用JAVA,将XML文件导入数据库，和将数据库信息导入到XML的笔记将到将到明后两天发布。

最后将分享一个利用XML当数据库，查询英语六级词汇的案例，下面先分享一下截图吧:

实例将到明后两天分享。请多多关注哟。

作者:Li-Cheng

出处:http://www.cnblogs.com/Li-Cheng/p/3610458.html

本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。