package wzs;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  XMLWriter{    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("MyXml.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", "utf-8");            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();        }       }}

<?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>