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JAVA操作XML文档主要有四种方式，分别是DOM、SAX、JDOM和DOM4J，DOM和SAX是官方提供的，而JDOM和DOM4J则是引用第三方库的，其中用的最多的是DOM4J方式。运行效率和内存使用方面最优的是SAX，但是由于SAX是基于事件的方式，所以SAX无法在编写XML的过程中对已编写内容进行修改，但对于不用进行频繁修改的需求，还是应该选择使用SAX。
下面基于这四种方式来读取XML文件。
第一，以DOM的方式实现。
package xmls;
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;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.io.File;
import java.io.IOException;
/**
* Created by lenovo on 2017-6-3.
*/
public class DOMReadDemo {
public static void main(String[] args){
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
try{
DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.parse("src/xmls/DOM.xml");
NodeList booklist = document.getElementsByTagName("book");
for(int i = 0; i < booklist.getLength(); i++){
System.out.println("--------第" + (i+1) + "本书----------");
Element ele = (Element) booklist.item(i);
NodeList childNodes= ele.getChildNodes();
for(int j = 0; j < childNodes.getLength(); j++){
Node n = childNodes.item(j);
if(n.getNodeName() != "#text"){
System.out.println(n.getNodeName() + ":" + n.getTextContent());
}
}
System.out.println("---------------------------------");
}
}catch (ParserConfigurationException e){
e.printStackTrace();
}catch (IOException e){
e.printStackTrace();
}catch (SAXException e){
e.printStackTrace();
}
}
}第二，以SAX的方式实现。
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package xmls;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
/**
* Created by lenovo on 2017-6-1.
*/
public class xmlTest2 {
public static void main(String[] args){
SAXParserFactory spf = SAXParserFactory.newInstance();
try{
SAXParser sp = spf.newSAXParser();
SAXParserHandler handler = new SAXParserHandler();
sp.parse("src\\xmls\\book.xml", handler);
}catch (Exception e){
e.printStackTrace();
}
}
}package xmls;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
* Created by lenovo on 2017-6-1.
*/
public class SAXParserHandler extends DefaultHandler {
@Override
public void startDocument() throws SAXException {
super.startDocument();
System.out.println("SAX解析开始");
}
@Override
public void endDocument() throws SAXException {
super.endDocument();
System.out.println("SAX解析结束");
}
@Override
public void startElement(String s, String s1, String s2, Attributes attributes) throws SAXException {
super.startElement(s, s1, s2, attributes);
System.out.println(s2);
for(int i = 0; i < attributes.getLength(); i++){
String name = attributes.getQName(i);
String value = attributes.getValue(name);
System.out.println("属性值：" + name + "=" + value);
}
}
@Override
public void endElement(String s, String s1, String s2) throws SAXException {
super.endElement(s, s1, s2);
if(s2.equals("book")){
System.out.println("-----------------------");
}
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
super.characters(ch, start, length);
String value = new String(ch, start, length);
if(value.trim().equals("")){
return;
}
System.out.println(value);
}
}第三，以JDOM的方式实现。
package xmls;
import org.jdom2.Attribute;
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.JDOMException;
import org.jdom2.input.JDOMParseException;
import org.jdom2.input.SAXBuilder;
import java.io.*;
import java.util.List;
/**
* Created by lenovo on 2017-6-2.
*/
public class JDOMTest {
public static void main(String[] args){
SAXBuilder saxBuilder = new SAXBuilder();
InputStream in;
try{
in = new FileInputStream(new File("src\\xmls\\book.xml"));
Document document = saxBuilder.build(in);
Element rootElement = document.getRootElement();
List bookList = rootElement.getChildren();
for(Element book: bookList){
System.out.println("第" + (bookList.indexOf(book)+1) + "本书！");
List attrs = book.getAttributes();
for(Attribute attr: attrs){
System.out.println(attr.getName() + "=" + attr.getValue());
}
for(Element item: book.getChildren()){
System.out.println(item.getName() + ":" + item.getValue());
}
System.out.println("------------------------------------");
}
}catch (FileNotFoundException e){
e.printStackTrace();
}catch (JDOMException e){
e.printStackTrace();
}catch (IOException e){
e.printStackTrace();
}
}
} 第四，以DOM4J的方式实现。
package xmls;
import org.dom4j.*;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
/**
* Created by lenovo on 2017-6-2.
*/
public class DOM4JTest {
public void parseXML(){
SAXReader saxReader = new SAXReader();
try{
Document document = saxReader.read(new File("src\\xmls\\book.xml"));
Element rootElement = document.getRootElement();
Iterator it = rootElement.elementIterator();
while (it.hasNext()){
Element book = (Element)it.next();
List attrs = book.attributes();
for(Attribute attr: attrs){
System.out.println("属性名：" + attr.getName() + "---- 属性值：" + attr.getValue() );
}
Iterator cit = book.elementIterator();
while (cit.hasNext()){
Element child = (Element) cit.next();
System.out.println("子节点：" + child.getName());
}
}
}catch (DocumentException e){
e.printStackTrace();
}
}
public static void main(String[] args){
DOM4JTest dom4JTest = new DOM4JTest();
dom4JTest.parseXML();
}
} 
