JAVA解析XML

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解析XML

XML现在已经成为一种通用的数据交换格式,平台的无关性使得很多场合都需要用到XML。本文将详细介绍用Java解析XML的四种方法。

XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),具体可参阅w3c官方网站文档http://www.w3.org获取更多信息。

XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已。基本的解析方式有两种,一种叫SAX，另一种叫DOM。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析。假设我们XML的内容和结构如下:

ddviplinux m 30

本文使用JAVA语言来实现DOM与SAX的XML文档生成与解析。

首先定义一个操作XML文档的接口XmlDocument 它定义了XML文档的建立与解析的接口。 package com.alisoft.facepay.framework.bean; /** *

* @author hongliang.dinghl * 定义XML文档建立与解析的接口 */

public interface XmlDocument { /**

* 建立XML文档

* @param fileName 文件全路径名称 */

public void createXml(String fileName); /**

* 解析XML文档

* @param fileName 文件全路径名称 */

public void parserXml(String fileName); }

1.DOM生成和解析XML文档为 XML 文档的已解析版本定义了一组接口。解析器读入整个文档，然后构建一个驻留内存的树结构，然后代码就可以使用 DOM 接口来操作这个树结构。优点：整个文档树在内存中，便于操作；支持删除、修改、重新排列等多种功能；缺点：将整个文档调入内存（包括无用的节点），浪费时间和空间；使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存、CPU）。

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Java代码

package com.alisoft.facepay.framework.bean; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter;

import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.transform.OutputKeys; 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.xml.sax.SAXException; /** *

* @author hongliang.dinghl * DOM生成与解析XML文档 */

public class DomDemo implements XmlDocument { private Document document; private String fileName; public void init() { try {

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); this.document = builder.newDocument(); } catch (ParserConfigurationException e) {

System.out.println(e.getMessage()); } }

public void createXml(String fileName) {

Element root = this.document.createElement(\"employees\"); this.document.appendChild(root);

Element employee = this.document.createElement(\"employee\");

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Element name = this.document.createElement(\"name\"); name.appendChild(this.document.createTextNode(\"丁宏亮\")); employee.appendChild(name);

Element sex = this.document.createElement(\"sex\"); sex.appendChild(this.document.createTextNode(\"m\")); employee.appendChild(sex);

Element age = this.document.createElement(\"age\"); age.appendChild(this.document.createTextNode(\"30\")); employee.appendChild(age); root.appendChild(employee);

TransformerFactory tf = TransformerFactory.newInstance(); try {

Transformer transformer = tf.newTransformer(); DOMSource source = new DOMSource(document);

transformer.setOutputProperty(OutputKeys.ENCODING, \"gb2312\"); transformer.setOutputProperty(OutputKeys.INDENT, \"yes\");

PrintWriter pw = new PrintWriter(new FileOutputStream(fileName)); StreamResult result = new StreamResult(pw); transformer.transform(source, result); System.out.println(\"生成XML文件成功!\"); } catch (TransformerConfigurationException e) {

System.out.println(e.getMessage()); } catch (IllegalArgumentException e) {

System.out.println(e.getMessage()); } catch (FileNotFoundException e) {

System.out.println(e.getMessage()); } catch (TransformerException e) {

System.out.println(e.getMessage()); } }

public void parserXml(String fileName) { try {

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document document = db.parse(fileName); NodeList employees = document.getChildNodes(); for (int i = 0; i < employees.getLength(); i++) {

Node employee = employees.item(i);

NodeList employeeInfo = employee.getChildNodes(); for (int j = 0; j < employeeInfo.getLength(); j++) {

Node node = employeeInfo.item(j);

NodeList employeeMeta = node.getChildNodes();

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for (int k = 0; k < employeeMeta.getLength(); k++) {

System.out.println(employeeMeta.item(k).getNodeName() + \":\" + employeeMeta.item(k).getTextContent()); } } }

System.out.println(\"解析完毕\"); } catch (FileNotFoundException e) {

System.out.println(e.getMessage()); } catch (ParserConfigurationException e) {

System.out.println(e.getMessage()); } catch (SAXException e) {

System.out.println(e.getMessage()); } catch (IOException e) {

System.out.println(e.getMessage()); } } }

2.SAX生成和解析XML文档为解决DOM的问题，出现了SAX。SAX ，事件驱动。当解析器发现元素开始、元素结束、文本、文档的开始或结束等时，发送事件，程序员编写响应这些事件的代码，保存数据。优点：不用事先调入整个文档，占用资源少；SAX解析器代码比DOM解析器代码小，适于Applet，下载。缺点：不是持久的；事件过后，若没保存数据，那么数据就丢了；无状态性；从事件中只能得到文本，但不知该文本属于哪个元素；使用场合：Applet;只需XML文档的少量内容，很少回头访问；机器内存少； Java代码

package com.alisoft.facepay.framework.bean; import java.io.FileInputStream; import java.io.FileNotFoundException; 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.SAXException;

import org.xml.sax.helpers.DefaultHandler; /** *

* @author hongliang.dinghl * SAX文档解析 */

public class SaxDemo implements XmlDocument { public void createXml(String fileName) {

System.out.println(\"<<\"+filename+\">>\"); }

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public void parserXml(String fileName) {

SAXParserFactory saxfac = SAXParserFactory.newInstance(); try {

SAXParser saxparser = saxfac.newSAXParser(); InputStream is = new FileInputStream(fileName); saxparser.parse(is, new MySAXHandler()); } catch (ParserConfigurationException e) {

e.printStackTrace(); } catch (SAXException e) {

e.printStackTrace();

} catch (FileNotFoundException e) {

e.printStackTrace(); } catch (IOException e) {

e.printStackTrace(); } } }

class MySAXHandler extends DefaultHandler {

boolean hasAttribute = false; Attributes attributes = null;

public void startDocument() throws SAXException {

System.out.println(\"文档开始打印了\"); }

public void endDocument() throws SAXException {

System.out.println(\"文档打印结束了\"); }

public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {

if (qName.equals(\"employees\")) { return; }

if (qName.equals(\"employee\")) {

System.out.println(qName); }

if (attributes.getLength() > 0) {

this.attributes = attributes; this.hasAttribute = true; } }

public void endElement(String uri, String localName, String qName) throws SAXException { if (hasAttribute && (attributes != null)) { for (int i = 0; i < attributes.getLength(); i++) {

System.out.println(attributes.getQName(0) + attributes.getValue(0)); }

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} }

public void characters(char[] ch, int start, int length) throws SAXException {

System.out.println(new String(ch, start, length)); } }

package com.alisoft.facepay.framework.bean; import java.io.FileInputStream; import java.io.FileNotFoundException; 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.SAXException;

import org.xml.sax.helpers.DefaultHandler; /** *

* @author hongliang.dinghl * SAX文档解析 */

public class SaxDemo implements XmlDocument { public void createXml(String fileName) {

System.out.println(\"<<\"+filename+\">>\"); }

public void parserXml(String fileName) {

SAXParserFactory saxfac = SAXParserFactory.newInstance(); try {

SAXParser saxparser = saxfac.newSAXParser(); InputStream is = new FileInputStream(fileName); saxparser.parse(is, new MySAXHandler()); } catch (ParserConfigurationException e) {

e.printStackTrace(); } catch (SAXException e) {

e.printStackTrace();

} catch (FileNotFoundException e) {

e.printStackTrace(); } catch (IOException e) {

e.printStackTrace(); } } }

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class MySAXHandler extends DefaultHandler {

boolean hasAttribute = false; Attributes attributes = null;

public void startDocument() throws SAXException {

System.out.println(\"文档开始打印了\"); }

public void endDocument() throws SAXException {

System.out.println(\"文档打印结束了\"); }

public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {

if (qName.equals(\"employees\")) {

return; }

if (qName.equals(\"employee\")) {

System.out.println(qName); }

if (attributes.getLength() > 0) {

this.attributes = attributes; this.hasAttribute = true; } }

public void endElement(String uri, String localName, String qName) throws SAXException { if (hasAttribute && (attributes != null)) {

for (int i = 0; i < attributes.getLength(); i++) {

System.out.println(attributes.getQName(0) + attributes.getValue(0)); } } }

public void characters(char[] ch, int start, int length) throws SAXException {

System.out.println(new String(ch, start, length)); } }

3.DOM4J生成和解析XML文档

DOM4J 是一个非常非常优秀的Java XML API，具有性能优异、功能强大和极端易用使用的特点，同时它也是一个开放源代码的软件。如今你可以看到越来越多的 Java 软件都在使用 DOM4J 来读写 XML，特别值得一提的是连 Sun 的 JAXM 也在用 DOM4J。 Java代码

package com.alisoft.facepay.framework.bean; import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.Writer;

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import java.util.Iterator; import org.dom4j.Document;

import org.dom4j.DocumentException; import org.dom4j.DocumentHelper; import org.dom4j.Element; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; /** *

* @author hongliang.dinghl

* Dom4j 生成XML文档与解析XML文档 */

public class Dom4jDemo implements XmlDocument { public void createXml(String fileName) {

Document document = DocumentHelper.createDocument(); Element employees=document.addElement(\"employees\"); Element employee=employees.addElement(\"employee\"); Element name= employee.addElement(\"name\"); name.setText(\"ddvip\");

Element sex=employee.addElement(\"sex\"); sex.setText(\"m\");

Element age=employee.addElement(\"age\"); age.setText(\"29\"); try {

Writer fileWriter=new FileWriter(fileName); XMLWriter xmlWriter=new XMLWriter(fileWriter); xmlWriter.write(document); xmlWriter.close(); } catch (IOException e) {

System.out.println(e.getMessage()); } }

public void parserXml(String fileName) {

File inputXml=new File(fileName); SAXReader saxReader = new SAXReader(); try {

Document document = saxReader.read(inputXml); Element employees=document.getRootElement(); for(Iterator i = employees.elementIterator(); i.hasNext();){

Element employee = (Element) i.next();

for(Iterator j = employee.elementIterator(); j.hasNext();){

Element node=(Element) j.next();

System.out.println(node.getName()+\":\"+node.getText()); }

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}

} catch (DocumentException e) {

System.out.println(e.getMessage()); }

System.out.println(\"dom4j parserXml\"); } }

4.JDOM生成和解析XML

为减少DOM、SAX的编码量，出现了JDOM；优点：20-80原则，极大减少了代码量。使用场合：要实现的功能简单，如解析、创建等，但在底层，JDOM还是使用SAX（最常用）、DOM、Xanan文档。 package com.alisoft.facepay.framework.bean; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.List;

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

* @author hongliang.dinghl * JDOM 生成与解析XML文档 * */

public class JDomDemo implements XmlDocument { public void createXml(String fileName) {

Document document; Element root;

root=new Element(\"employees\"); document=new Document(root);

Element employee=new Element(\"employee\"); root.addContent(employee);

Element name=new Element(\"name\"); name.setText(\"ddvip\"); employee.addContent(name); Element sex=new Element(\"sex\"); sex.setText(\"m\");

employee.addContent(sex); Element age=new Element(\"age\"); age.setText(\"23\");

employee.addContent(age);

XMLOutputter XMLOut = new XMLOutputter();

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try {

XMLOut.output(document, new FileOutputStream(fileName)); } catch (FileNotFoundException e) {

e.printStackTrace(); } catch (IOException e) {

e.printStackTrace(); } }

public void parserXml(String fileName) {

SAXBuilder builder=new SAXBuilder(false); try {

Document document=builder.build(fileName); Element employees=document.getRootElement(); List employeeList=employees.getChildren(\"employee\"); for(int i=0;i

Element employee=(Element)employeeList.get(i); List employeeInfo=employee.getChildren(); for(int j=0;j

System.out.println(((Element)employeeInfo.get(j)).getName()+\":\"+((Element)employeeInfo.get(j)).getValue()); } }

} catch (JDOMException e) {

e.printStackTrace(); } catch (IOException e) {

e.printStackTrace(); } } }

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