JAVA操作XML的完整例子

这是一个用JAVA W3C DOM 进行XML操作的例子，包含了查询、增加、修改、删除、保存的基本操作。较完整的描述了一个XML的整个操作流程。适合刚入门JAVA XML操作的朋友参考和学习。

假设有XML文件：test1.xml


<?xml version="1.0" encoding="UTF-8"?>


<books>


<book>


<name>哈里波特</name>


<price>10</price>


<memo>这是一本很好看的书。</memo>


</book>


<book id="B02">


<name>三国演义</name>


<price>10</price>


<memo>四大名著之一。</memo>


</book>


<book id="B03">


<name>水浒</name>


<price>6</price>


<memo>四大名著之一。</memo>


</book>


<book id="B04">


<name>红楼</name>


<price>5</price>


<memo>四大名著之一。</memo>


</book>


</books>



下面是为Test.java


import java.io.File;


import java.io.FileNotFoundException;


import java.io.FileOutputStream;


import java.io.IOException;




import org.w3c.dom.*;


import org.xml.sax.SAXException;




import javax.xml.parsers.*;


import javax.xml.transform.*;


import javax.xml.transform.dom.DOMSource;


import javax.xml.transform.stream.*;


import javax.xml.xpath.*;






public class Test ...{




public static void main(String[] args) ...{


DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();


Element theBook=null, theElem=null, root=null;




try ...{


factory.setIgnoringElementContentWhitespace(true);




DocumentBuilder db=factory.newDocumentBuilder();


Document xmldoc=db.parse(new File("Test1.xml"));


root=xmldoc.getDocumentElement();




//--- 新建一本书开始 ----


theBook=xmldoc.createElement("book");


theElem=xmldoc.createElement("name");


theElem.setTextContent("新书");


theBook.appendChild(theElem);




theElem=xmldoc.createElement("price");


theElem.setTextContent("20");


theBook.appendChild(theElem);




theElem=xmldoc.createElement("memo");


theElem.setTextContent("新书的更好看。");


theBook.appendChild(theElem);


root.appendChild(theBook);


System.out.println("--- 新建一本书开始 ----");


output(xmldoc);


//--- 新建一本书完成 ----




//--- 下面对《哈里波特》做一些修改。 ----


//--- 查询找《哈里波特》----


theBook=(Element) selectSingleNode("/books/book[name='哈里波特']", root);


System.out.println("--- 查询找《哈里波特》 ----");


output(theBook);


//--- 此时修改这本书的价格 -----


theBook.getElementsByTagName("price").item(0).setTextContent("15");//getElementsByTagName返回的是NodeList，所以要跟上item(0)。另外，getElementsByTagName("price")相当于xpath的".//price"。


System.out.println("--- 此时修改这本书的价格 ----");


output(theBook);


//--- 另外还想加一个属性id，值为B01 ----


theBook.setAttribute("id", "B01");


System.out.println("--- 另外还想加一个属性id，值为B01 ----");


output(theBook);


//--- 对《哈里波特》修改完成。 ----




//--- 要用id属性删除《三国演义》这本书 ----


theBook=(Element) selectSingleNode("/books/book[@id='B02']", root);


System.out.println("--- 要用id属性删除《三国演义》这本书 ----");


output(theBook);


theBook.getParentNode().removeChild(theBook);


System.out.println("--- 删除后的ＸＭＬ ----");


output(xmldoc);




//--- 再将所有价格低于10的书删除 ----


NodeList someBooks=selectNodes("/books/book[price<10]", root);


System.out.println("--- 再将所有价格低于10的书删除 ---");


System.out.println("--- 符合条件的书有　"+someBooks.getLength()+"本。 ---");




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


someBooks.item(i).getParentNode().removeChild(someBooks.item(i));


}


output(xmldoc);




saveXml("Test1_Edited.xml", xmldoc);




} catch (ParserConfigurationException e) ...{


e.printStackTrace();




} catch (SAXException e) ...{


e.printStackTrace();




} catch (IOException e) ...{


e.printStackTrace();


}


}






public static void output(Node node) ...{//将node的XML字符串输出到控制台


TransformerFactory transFactory=TransformerFactory.newInstance();




try ...{


Transformer transformer = transFactory.newTransformer();


transformer.setOutputProperty("encoding", "gb2312");


transformer.setOutputProperty("indent", "yes");




DOMSource source=new DOMSource();


source.setNode(node);


StreamResult result=new StreamResult();


result.setOutputStream(System.out);




transformer.transform(source, result);




} catch (TransformerConfigurationException e) ...{


e.printStackTrace();




} catch (TransformerException e) ...{


e.printStackTrace();


}


}






public static Node selectSingleNode(String express, Object source) ...{//查找节点，并返回第一个符合条件节点


Node result=null;


XPathFactory xpathFactory=XPathFactory.newInstance();


XPath xpath=xpathFactory.newXPath();




try ...{


result=(Node) xpath.evaluate(express, source, XPathConstants.NODE);




} catch (XPathExpressionException e) ...{


e.printStackTrace();


}




return result;


}






public static NodeList selectNodes(String express, Object source) ...{//查找节点，返回符合条件的节点集。


NodeList result=null;


XPathFactory xpathFactory=XPathFactory.newInstance();


XPath xpath=xpathFactory.newXPath();




try ...{


result=(NodeList) xpath.evaluate(express, source, XPathConstants.NODESET);




} catch (XPathExpressionException e) ...{


e.printStackTrace();


}




return result;


}






public static void saveXml(String fileName, Document doc) ...{//将Document输出到文件


TransformerFactory transFactory=TransformerFactory.newInstance();




try ...{


Transformer transformer = transFactory.newTransformer();


transformer.setOutputProperty("indent", "yes");




DOMSource source=new DOMSource();


source.setNode(doc);


StreamResult result=new StreamResult();


result.setOutputStream(new FileOutputStream(fileName));




transformer.transform(source, result);




} catch (TransformerConfigurationException e) ...{


e.printStackTrace();




} catch (TransformerException e) ...{


e.printStackTrace();




} catch (FileNotFoundException e) ...{


e.printStackTrace();


}


}


}