读取XML文件

Posted 2020-09-21 牧云人生

   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 }

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    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 }

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 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     @Override
10     public void startDocument() throws SAXException {
11         super.startDocument();
12         System.out.println("SAX解析开始");
13     }
14     @Override
15     public void endDocument() throws SAXException {
16         super.endDocument();
17         System.out.println("SAX解析结束");
18     }
19     @Override
20     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     @Override
30     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     @Override
37     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 }

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    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 }

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    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 }

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