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。
1 package xmls; 2 import org.w3c.dom.Document; 3 import org.w3c.dom.Element; 4 import org.w3c.dom.Node; 5 import org.w3c.dom.NodeList; 6 import org.xml.sax.SAXException; 7 import javax.xml.parsers.DocumentBuilder; 8 import javax.xml.parsers.DocumentBuilderFactory; 9 import javax.xml.parsers.ParserConfigurationException;10 import java.io.File;11 import java.io.IOException;12 /**13 * Created by lenovo on 2017-6-3.14 */15 public class DOMReadDemo {16 public static void main(String[] args){17 DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();18 try{19 DocumentBuilder db = dbf.newDocumentBuilder();20 Document document = db.parse("src/xmls/DOM.xml");21 NodeList booklist = document.getElementsByTagName("book");22 for(int i = 0; i < booklist.getLength(); i++){23 System.out.println("--------第" + (i+1) + "本书----------");24 Element ele = (Element) booklist.item(i);25 NodeList childNodes= ele.getChildNodes();26 for(int j = 0; j < childNodes.getLength(); j++){27 Node n = childNodes.item(j);28 if(n.getNodeName() != "#text"){29 System.out.println(n.getNodeName() + ":" + n.getTextContent());30 }31 }32 System.out.println("---------------------------------");33 }34 }catch (ParserConfigurationException e){35 e.printStackTrace();36 }catch (IOException e){37 e.printStackTrace();38 }catch (SAXException e){39 e.printStackTrace();40 }41 }42 }
第二，以SAX的方式实现。
1 package xmls; 2 import javax.xml.parsers.SAXParser; 3 import javax.xml.parsers.SAXParserFactory; 4 /** 5 * Created by lenovo on 2017-6-1. 6 */ 7 public class xmlTest2 { 8 public static void main(String[] args){ 9 SAXParserFactory spf = SAXParserFactory.newInstance();10 try{11 SAXParser sp = spf.newSAXParser();12 SAXParserHandler handler = new SAXParserHandler();13 sp.parse("src\xmls\book.xml", handler);14 }catch (Exception e){15 e.printStackTrace();16 }17 }18 }
1 package xmls; 2 import org.xml.sax.Attributes; 3 import org.xml.sax.SAXException; 4 import org.xml.sax.helpers.DefaultHandler; 5 /** 6 * Created by lenovo on 2017-6-1. 7 */ 8 public class SAXParserHandler extends DefaultHandler { 9 @Override10 public void startDocument() throws SAXException {11 super.startDocument();12 System.out.println("SAX解析开始");13 }14 @Override15 public void endDocument() throws SAXException {16 super.endDocument();17 System.out.println("SAX解析结束");18 }19 @Override20 public void startElement(String s, String s1, String s2, Attributes attributes) throws SAXException {21 super.startElement(s, s1, s2, attributes);22 System.out.println(s2);23 for(int i = 0; i < attributes.getLength(); i++){24 String name = attributes.getQName(i);25 String value = attributes.getValue(name);26 System.out.println("属性值：" + name + "=" + value);27 }28 }29 @Override30 public void endElement(String s, String s1, String s2) throws SAXException {31 super.endElement(s, s1, s2);32 if(s2.equals("book")){33 System.out.println("-----------------------");34 }35 }36 @Override37 public void characters(char[] ch, int start, int length) throws SAXException {38 super.characters(ch, start, length);39 String value = new String(ch, start, length);40 if(value.trim().equals("")){41 return;42 }43 System.out.println(value);44 }45 }
第三，以JDOM的方式实现。
1 package xmls; 2 import org.jdom2.Attribute; 3 import org.jdom2.Document; 4 import org.jdom2.Element; 5 import org.jdom2.JDOMException; 6 import org.jdom2.input.JDOMParseException; 7 import org.jdom2.input.SAXBuilder; 8 import java.io.*; 9 import java.util.List;10 /**11 * Created by lenovo on 2017-6-2.12 */13 public class JDOMTest {14 public static void main(String[] args){15 SAXBuilder saxBuilder = new SAXBuilder();16 InputStream in;17 try{18 in = new FileInputStream(new File("src\xmls\book.xml"));19 Document document = saxBuilder.build(in);20 Element rootElement = document.getRootElement();21 List<Element> bookList = rootElement.getChildren();22 for(Element book: bookList){23 System.out.println("第" + (bookList.indexOf(book)+1) + "本书！");24 List<Attribute> attrs = book.getAttributes();25 for(Attribute attr: attrs){26 System.out.println(attr.getName() + "=" + attr.getValue());27 }28 for(Element item: book.getChildren()){29 System.out.println(item.getName() + ":" + item.getValue());30 }31 System.out.println("------------------------------------");32 }33 }catch (FileNotFoundException e){34 e.printStackTrace();35 }catch (JDOMException e){36 e.printStackTrace();37 }catch (IOException e){38 e.printStackTrace();39 }40 }41 }
第四，以DOM4J的方式实现。
1 package xmls; 2 import org.dom4j.*; 3 import org.dom4j.io.OutputFormat; 4 import org.dom4j.io.SAXReader; 5 import org.dom4j.io.XMLWriter; 6 import java.io.File; 7 import java.io.FileOutputStream; 8 import java.io.IOException; 9 import java.util.Iterator;10 import java.util.List;11 /**12 * Created by lenovo on 2017-6-2.13 */14 public class DOM4JTest {15 public void parseXML(){16 SAXReader saxReader = new SAXReader();17 try{18 Document document = saxReader.read(new File("src\xmls\book.xml"));19 Element rootElement = document.getRootElement();20 Iterator it = rootElement.elementIterator();21 while (it.hasNext()){22 Element book = (Element)it.next();23 List<Attribute> attrs = book.attributes();24 for(Attribute attr: attrs){25 System.out.println("属性名：" + attr.getName() + "---- 属性值：" + attr.getValue() );26 }27 Iterator cit = book.elementIterator();28 while (cit.hasNext()){29 Element child = (Element) cit.next();30 System.out.println("子节点：" + child.getName());31 }32 }33 }catch (DocumentException e){34 e.printStackTrace();35 }36 }37 public static void main(String[] args){38 DOM4JTest dom4JTest = new DOM4JTest();39 dom4JTest.parseXML();40 }41 }
