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:

  <?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。

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）。
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");
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
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();  
 
        }  
 
    }  
 
}  
 
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));  
 
    }  
 
} 

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();

}

}

}

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;  
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());  
                 }  
 
            }  
        } 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。  
<PRE class=java name="code">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();  
      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<employeeList.size();i++){  
                Element employee=(Element)employeeList.get(i);  
                List employeeInfo=employee.getChildren();  
                for(int j=0;j<employeeInfo.size();j++){  
                    System.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue());  
                      
                }  
            }  
        } catch (JDOMException e) {  
          
            e.printStackTrace();  
        } catch (IOException e) {  
          
            e.printStackTrace();  
        }   
 
    }  
}  
  </PRE>