Java解析XML汇总(DOM/SAX/JDOM/DOM4j/XPath)
2012-01-12 11:02
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一、【基础知识——扫盲】
二、【DOM、SAX、JDOM、DOM4j简单使用介绍】
三、【性能测试】
四、【对比】
五、【小插曲XPath】
六、【补充】
关键字:Java解析xml、解析xml四种方法、DOM、SAX、JDOM、DOM4j、XPath
【引言】
目前在Java中用于解析XML的技术很多,主流的有DOM、SAX、JDOM、DOM4j,下文主要介绍这4种解析XML文档技术的使用、优缺点及性能测试。一、【基础知识——扫盲】
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)。二、【DOM、SAX、JDOM、DOM4j简单使用介绍】
1、【DOM(Document Object Model) 】由W3C提供的接口,它将整个XML文档读入内存,构建一个DOM树来对各个节点(Node)进行操作。
示例代码:
[html]
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<?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>
[java] view plaincopyprint? package test.xml; 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 * @author whwang */ public class TestDom { public static void main(String[] args) { read(); //write(); } public static void read() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder builder = dbf.newDocumentBuilder(); InputStream in = TestDom.class.getClassLoader().getResourceAsStream("test.xml"); Document doc = builder.parse(in); // root <university> Element root = doc.getDocumentElement(); if (root == null) return; System.err.println(root.getAttribute("name")); // all college node NodeList collegeNodes = root.getChildNodes(); if (collegeNodes == null) return; for(int i = 0; i < collegeNodes.getLength(); i++) { Node college = collegeNodes.item(i); if (college != null && college.getNodeType() == Node.ELEMENT_NODE) { System.err.println("\t" + college.getAttributes().getNamedItem("name").getNodeValue()); // all class node 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("\t\t" + clazz.getAttributes().getNamedItem("name").getNodeValue()); // all student node 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("\t\t\t" + 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(); } } public static void write() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder builder = dbf.newDocumentBuilder(); InputStream in = TestDom.class.getClassLoader().getResourceAsStream("test.xml"); Document doc = builder.parse(in); // root <university> Element root = doc.getDocumentElement(); if (root == null) return; // 修改属性 root.setAttribute("name", "tsu"); 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()); } 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(); } } } package test.xml; 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 * @author whwang */ public class TestDom { public static void main(String[] args) { read(); //write(); } public static void read() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder builder = dbf.newDocumentBuilder(); InputStream in = TestDom.class.getClassLoader().getResourceAsStream("test.xml"); Document doc = builder.parse(in); // root <university> Element root = doc.getDocumentElement(); if (root == null) return; System.err.println(root.getAttribute("name")); // all college node NodeList collegeNodes = root.getChildNodes(); if (collegeNodes == null) return; for(int i = 0; i < collegeNodes.getLength(); i++) { Node college = collegeNodes.item(i); if (college != null && college.getNodeType() == Node.ELEMENT_NODE) { System.err.println("\t" + college.getAttributes().getNamedItem("name").getNodeValue()); // all class node 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("\t\t" + clazz.getAttributes().getNamedItem("name").getNodeValue()); // all student node 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("\t\t\t" + 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(); } } public static void write() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder builder = dbf.newDocumentBuilder(); InputStream in = TestDom.class.getClassLoader().getResourceAsStream("test.xml"); Document doc = builder.parse(in); // root <university> Element root = doc.getDocumentElement(); if (root == null) return; // 修改属性 root.setAttribute("name", "tsu"); 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()); } 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(); } } }该代码只要稍做修改,即可变得更加简洁,无需一直写if来判断是否有子节点。
2、【SAX (Simple API for XML) 】
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,重写自己感兴趣的事件即可。
示例代码:
[java]
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package test.xml;
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("test.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("]");
}
}
[java] view plaincopyprint? package test.xml; 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("test.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 += "\t"; 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("test.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(); } } } package test.xml; 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("test.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 += "\t"; 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("test.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(); } } }4、【DOM4j】
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
示例代码:
[java]
view plaincopyprint?
package test.xml;
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("test.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 += "\t";
for (Element e : childNodes) {
readNode(e, prefix);
}
}
public static void read2() {
try {
SAXReader reader = new SAXReader();
InputStream in = TestDom4j.class.getClassLoader().getResourceAsStream("test.xml");
Document doc = reader.read(in);
doc.accept(new MyVistor());
} catch (DocumentException e) {
e.printStackTrace();
}
}
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());
}
}
[java] view plaincopyprint? package test.xml; 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; 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("test.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(); } } } package test.xml; 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; 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("test.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(); } } }六、【补充】
注意4种解析方法对TextNode(文本节点)的处理:
1、在使用DOM时,调用node.getChildNodes()获取该节点的子节点,文本节点也会被当作一个Node来返回,如:
[html]
view plaincopyprint?
<?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>
</college>
</university>
[java] view plaincopyprint? package test.xml; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.util.Arrays; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; /** * dom读写xml * @author whwang */ public class TestDom2 { public static void main(String[] args) { read(); } public static void read() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder builder = dbf.newDocumentBuilder(); InputStream in = TestDom2.class.getClassLoader().getResourceAsStream("test.xml"); Document doc = builder.parse(in); // root <university> Element root = doc.getDocumentElement(); if (root == null) return; // System.err.println(root.getAttribute("name")); // all college node NodeList collegeNodes = root.getChildNodes(); if (collegeNodes == null) return; System.err.println("university子节点数:" + collegeNodes.getLength()); System.err.println("子节点如下:"); for(int i = 0; i < collegeNodes.getLength(); i++) { Node college = collegeNodes.item(i); if (college == null) continue; if (college.getNodeType() == Node.ELEMENT_NODE) { System.err.println("\t元素节点:" + college.getNodeName()); } else if (college.getNodeType() == Node.TEXT_NODE) { System.err.println("\t文本节点:" + Arrays.toString(college.getTextContent().getBytes())); } } } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } package test.xml; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.util.Arrays; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; /** * dom读写xml * @author whwang */ public class TestDom2 { public static void main(String[] args) { read(); } public static void read() { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder builder = dbf.newDocumentBuilder(); InputStream in = TestDom2.class.getClassLoader().getResourceAsStream("test.xml"); Document doc = builder.parse(in); // root <university> Element root = doc.getDocumentElement(); if (root == null) return; // System.err.println(root.getAttribute("name")); // all college node NodeList collegeNodes = root.getChildNodes(); if (collegeNodes == null) return; System.err.println("university子节点数:" + collegeNodes.getLength()); System.err.println("子节点如下:"); for(int i = 0; i < collegeNodes.getLength(); i++) { Node college = collegeNodes.item(i); if (college == null) continue; if (college.getNodeType() == Node.ELEMENT_NODE) { System.err.println("\t元素节点:" + college.getNodeName()); } else if (college.getNodeType() == Node.TEXT_NODE) { System.err.println("\t文本节点:" + Arrays.toString(college.getTextContent().getBytes())); } } } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }输出的结果是:
[java]
view plaincopyprint?
university子节点数:3
子节点如下:
文本节点:[10, 9]
元素节点:college
文本节点:[10]
[html] view plaincopyprint? <?xml version="1.0" encoding="UTF-8"?> <university name="pku">11 <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> </college>22 </university> <?xml version="1.0" encoding="UTF-8"?> <university name="pku">11 <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> </college>22 </university>还是上面的程序,输出结果为:
[java]
view plaincopyprint?
university子节点数:3
子节点如下:
文本节点:[49, 49, 10, 9]
元素节点:college
文本节点:[50, 50, 10]
university子节点数:3
子节点如下:
文本节点:[49, 49, 10, 9]
元素节点:college
文本节点:[50, 50, 10]其中数字1的ASCII码为49,数字2的ASCII码为50。
2、使用SAX来解析同DOM,当你重写它的public void characters(char[] ch, int start, int length)方法时,你就能看到。
3、JDOM,调用node.getChildren()只返回子节点,不包括TextNode节点(不管该节点是否有Text信息)。如果要获取该节点的Text信息,可以调用node.getText()方法,该方法返回节点的Text信息,也包括\n\t等特殊字符。
4、DOM4j同JDOM
参考:
http://www.docin.com/p-78963650.html http://wenku.baidu.com/view/b091f9360b4c2e3f5727638b.html http://kree.iteye.com/blog/668280
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