java解析XML的方式

java解析XML的方式

博客分类： xmljava

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:
Xml代码 
<?xml version="1.0" encoding="UTF-8"?>  
  <employees>  
    <employee>  
      <name>ddviplinux</name>  
      <sex>m</sex>  
      <age>30</age>  
    </employee>  
  </employees> 
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。
Java代码 
public interface XmlDocument {       
     public void createXml(String fileName);         
     public void parserXml(String fileName);  
   
Xml代码 
<strong>1.DOM生成和解析XML文档</strong> 
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）。

Java代码 
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");  
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();  
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 
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;    
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();    
}    
}    
}    
 
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 
import java.io.File;    
import java.io.FileWriter;    
import java.io.IOException;    
import java.io.Writer;    
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;    
 
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());    
}    
}    
} 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。

Java代码 
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;    
 
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();    
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();    
}     
}    
}