DOM4XML

(一)新建一个xml文件，然后往里面添加元素

package com.util;import java.io.File;import java.io.IOException;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.*;import org.xml.sax.SAXException;public class Writer {private Document doc;private Element root;public void parseDocAndCreateFile(){try {DocumentBuilderFactory dFac=DocumentBuilderFactory.newInstance();DocumentBuilder dBud=dFac.newDocumentBuilder();// this.doc=dBud.parse(this.f);doc=dBud.newDocument();} catch (ParserConfigurationException e) {// TODO 自动生成 catch 块e.printStackTrace();}}public void initDoc(){this.root=doc.createElement("musiclession");this.doc.appendChild(this.root);}// public void saveDoc(){// this.doc.appendChild(this.root);// }public void writeStu(String id,String name ,int age,int score){Element eStu=doc.createElement("student");Element eName=doc.createElement("name");eName.appendChild(doc.createTextNode(name));Attr aId=doc.createAttribute("ID");aId.appendChild(doc.createTextNode(id));Element eAge=doc.createElement("age");eAge.appendChild(doc.createTextNode(String.valueOf(age)));Element eScore=doc.createElement("score");eScore.appendChild(doc.createTextNode(String.valueOf(score)));eStu.setAttributeNode(aId);eStu.appendChild(eName);eStu.appendChild(eAge);eStu.appendChild(eScore);System.out.println("ok");this.root.appendChild(eStu);}// public void printDoc(){// Element e=doc.getDocumentElement();// System.out.println(e.getTagName());// }public void saveDoc(String filename){File f=new File(filename);try {TransformerFactory tfFac=TransformerFactory.newInstance();Transformer tf=tfFac.newTransformer();//要使用 tf.transform(source, result)方法StreamResult result=new StreamResult(f);DOMSource source=new DOMSource(this.doc);tf.setOutputProperty(OutputKeys.VERSION, "1.0");tf.setOutputProperty(OutputKeys.ENCODING, "gb2312");tf.setOutputProperty(OutputKeys.INDENT, "yes");tf.transform(source, result);} catch (TransformerConfigurationException e) {// TODO 自动生成 catch 块e.printStackTrace();} catch (TransformerException e) {// TODO 自动生成 catch 块e.printStackTrace();}}public static void main(String [] args){Writer w=new Writer();w.parseDocAndCreateFile();w.initDoc();w.writeStu("s101","李华" , 12, 92);w.writeStu("s102", "笑林", 22, 82);w.writeStu("s103", "王明", 18, 90);//w.writeStu("11111", "11111", 18, 90);//w.saveDoc();//w.printDoc();w.saveDoc("F://testDoc//DOM4XML//student.xml");}} 

（二）读取一个已有xml，修改元素的值和添加新元素

package com.util;import java.io.File;import java.io.IOException;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.ParserConfigurationException;import javax.xml.transform.OutputKeys;import javax.xml.transform.TransformerFactory;import javax.xml.transform.Transformer;import javax.xml.transform.TransformerConfigurationException;import javax.xml.transform.TransformerException;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;import org.w3c.dom.*;import org.xml.sax.SAXException;public class DOMConvert {public static void main(String[] args) {DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();try {DocumentBuilder db = dbf.newDocumentBuilder();Document doc = db.parse("F://testDoc//DOM4XML//students.xml");Element eltStu = doc.createElement("student");Element eltName = doc.createElement("name");Element eltAge = doc.createElement("age");Attr attr = doc.createAttribute("sn");attr.setValue("03");Text txtName = doc.createTextNode("王五");Text txtAge = doc.createTextNode("19");eltName.appendChild(txtName);eltAge.appendChild(txtAge);eltStu.appendChild(eltName);eltStu.appendChild(eltAge);eltStu.setAttributeNode(attr);Element eltRoot = doc.getDocumentElement();//新增元素eltRoot.appendChild(eltStu);NodeList nl = doc.getElementsByTagName("student");// Node nodeDel=(Element)nl.item(0);// nodeDel.getParentNode().removeChild(nodeDel);//修改某个元素的值Element eltChg = (Element) nl.item(0);Node nodeAgeChg = eltChg.getElementsByTagName("age").item(0);nodeAgeChg.getFirstChild().setNodeValue("22");// 利用文档节点创建一个DOM输入源DOMSource source = new DOMSource(doc);// new File一个文件构造一个StreamResult对象，用于保存转换后结果。这里File为原来的文件，即实现了修改原xml文件的功能。StreamResult result = new StreamResult(new File("F://testDoc//DOM4XML//students.xml"));// 得到转换器工厂类的实例TransformerFactory tff = TransformerFactory.newInstance();// 创建一个新的转换器，用于执行恒等转换，// 即直接将DOM输入源的内容复制到结果文档中。Transformer tf = tff.newTransformer();tf.setOutputProperty(OutputKeys.VERSION, "1.0");tf.setOutputProperty(OutputKeys.ENCODING, "gb2312");tf.setOutputProperty(OutputKeys.INDENT, "yes");// 执行转换tf.transform(source, result);} catch (ParserConfigurationException e) {e.printStackTrace();} catch (SAXException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} catch (TransformerConfigurationException e) {e.printStackTrace();} catch (TransformerException e) {e.printStackTrace();}}} 

对xml文件修改后关键是用转换器进行修改：

try{// 利用文档节点创建一个DOM输入源DOMSource source = new DOMSource(doc);// new File一个文件构造一个StreamResult对象，用于保存转换后结果。这里File为原来的文件，即实现了修改原xml文件的功能。StreamResult result = new StreamResult(new File("F://testDoc//DOM4XML//students.xml"));// 得到转换器工厂类的实例TransformerFactory tff = TransformerFactory.newInstance();// 创建一个新的转换器，用于执行恒等转换，// 即直接将DOM输入源的内容复制到结果文档中。Transformer tf = tff.newTransformer();tf.setOutputProperty(OutputKeys.VERSION, "1.0");tf.setOutputProperty(OutputKeys.ENCODING, "gb2312");tf.setOutputProperty(OutputKeys.INDENT, "yes");// 执行转换tf.transform(source, result);} catch (ParserConfigurationException e) {e.printStackTrace();} catch (SAXException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} catch (TransformerConfigurationException e) {e.printStackTrace();} catch (TransformerException e) {e.printStackTrace();} 

（三）对xml进行parse时，文件名不能有空格或中文，否则报错如下：

 

java.net.MalformedURLException: unknown protocol: d

at java.net.URL.<init>(URL.java:574)

at java.net.URL.<init>(URL.java:464)

at java.net.URL.<init>(URL.java:413)

at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:650)

at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(XMLVersionDetector.java:186)

at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:771)

at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)

at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)

at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:225)

at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283)

at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:180)

at com.util.testDOMQuestion.writeXML(testDOMQuestion.java:51)

at com.util.testDOMQuestion.main(testDOMQuestion.java:111)

 

 

解决方法：用File类表示文件！

 

DocumentBuilder db = dbf.newDocumentBuilder();

File file = new File(fileaddr); 

Document doc = db.parse(file);