java学习之xml

xml的处理有两种方式dom和Sax

其中dom有3套api ，分别是dom和jdom和dom4j

 package com.gh.xml;

 import java.io.File;

 import java.util.ArrayList;

 import java.util.List;

 import javax.xml.parsers.DocumentBuilder;

 import javax.xml.parsers.DocumentBuilderFactory;

 import org.w3c.dom.Document;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 /**

  * Dom模式读取xml

  * @author ganhang

  *

  */

 public class DomDemo {

     public static void main(String[] args) throws Exception {

         // 创建dom解析器工厂

         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

         // 创建一个dom解析器

         DocumentBuilder db = dbf.newDocumentBuilder();

         // 关联文件

         File f = new File("src/1.xml");

         // 开始解析

         Document doc = db.parse(f);// 传文件或者字节流

         // 根据节点获取数据

         NodeList nl = doc.getElementsByTagName("teacher");

         List<Teacher> teachers = new ArrayList<Teacher>();

         Teacher t = null;

         for (int i = 0; i < nl.getLength(); i++) {

             Node teacherNode = nl.item(i);// 获取每个teacher节点

             // 得到节点的属性id的值

             String str = teacherNode.getAttributes().getNamedItem("id")

                     .getNodeValue();

             //System.out.println(str);

             t = new Teacher();

             t.setId(Integer.parseInt(str));

             // 获取teacher节点下的所有子节点

             NodeList childNodeList = teacherNode.getChildNodes();

             //System.out.println(childNodeList.getLength());

             for (int j = 0; j < childNodeList.getLength(); j++) {

                 // 注意teacher有三个子节点#text name #text

                 Node childNode = childNodeList.item(j);

                 //System.out.println(childNode.getNodeName());

                 // 取name的子节点的值

                 if ("name".equals(childNode.getNodeName())) {

                     t.setName(childNode.getFirstChild().getNodeValue());

                 }

             }

             teachers.add(t);

         }

         System.out.println(teachers);

     }

 }

 package com.gh.xml;

 import java.io.InputStream;

 import java.util.ArrayList;

 import java.util.List;

 import org.jdom2.Document;

 import org.jdom2.Element;

 import org.jdom2.input.SAXBuilder;

 public class JdomDemo {

     public static void main(String[] args) throws Exception {

         SAXBuilder sb = new SAXBuilder();// 创建jdom解析器

         InputStream in = Thread.currentThread().getContextClassLoader()

                 .getResourceAsStream("1.xml");

         Document doc = sb.build(in);

         //拿根元素

         Element roote = doc.getRootElement();

         //根据根元素拿子元素

         List<Element> liste = roote.getChildren();

         List<Teacher> teachers=new ArrayList<Teacher>();

         Teacher t=null;//注意必须要在里面new，不然teachers添加的都是重复的t；

         //遍历子元素,也可以返回一个iterator遍历；

         for (int i = 0; i < liste.size(); i++) {

             t=new Teacher();

             Element e = liste.get(i);

             t.setId(Integer.parseInt(e.getAttributeValue("id")));

             t.setName(e.getChildText("name"));

             teachers.add(t);

         }

         System.out.println(teachers);

     }

 }

 package com.gh.xml;

 import java.io.File;

 import java.util.ArrayList;

 import java.util.Iterator;

 import java.util.List;

 import org.dom4j.Document;

 import org.dom4j.Element;

 import org.dom4j.io.SAXReader;

 /**

  * Dom4j 性能最好

  * @author ganhang

  *

  */

 public class Dom4jDemo {

     public static void main(String[] args) throws Exception {

         SAXReader sr=new SAXReader();

         File f=new File("src/1.xml");

         Document doc=sr.read(f);

         Element roote=doc.getRootElement();

         Iterator<Element> iters=roote.elementIterator();

         Teacher t=null;

         List<Teacher> list=new ArrayList<Teacher>();

         while(iters.hasNext()){

             t=new Teacher();

             Element e=iters.next();

             t.setId(Integer.parseInt(e.attributeValue("id")));

             t.setName(e.elementText("name"));

             list.add(t);

         }

         System.out.println(list);

     }

 }

 package com.gh.xml;

 import java.io.InputStream;

 import javax.xml.parsers.SAXParser;

 import javax.xml.parsers.SAXParserFactory;

 /**

  * SAX读xml

  * @author ganhang

  *

  */

 public class SaxDemo {

     public static void main(String[] args) throws Exception {

         //创建SAX解析器工厂

         SAXParserFactory spf = SAXParserFactory.newInstance();

         //创建sax解析器

         SAXParser sp = spf.newSAXParser();

         //用字符流读xml

         InputStream is = Thread.currentThread().getContextClassLoader()

                 .getResourceAsStream("1.xml");

         MyHandler dh=new MyHandler();//实例化引擎

         //开始解析

         sp.parse(is, dh);

         System.out.println(dh.getList());

     }

 }

 package com.gh.xml;

 import java.util.ArrayList;

 import java.util.List;

 import org.xml.sax.Attributes;

 import org.xml.sax.SAXException;

 import org.xml.sax.helpers.DefaultHandler;

 /**

  * Sax模式的事件处理引擎

  * @author ganhang

  *

  */

 public class MyHandler extends DefaultHandler {

     private List<Teacher> list = null;

     private Teacher t = null;

     private String flag = null;

     //开始读入文件

     @Override

     public void startDocument() throws SAXException {

         list=new ArrayList<Teacher>();

     }

     //开始读元素

     @Override

     public void startElement(String uri, String localName, String qName,

             Attributes attributes) throws SAXException {

         flag = qName;

         if ("teacher".equals(qName)) {

             t=new Teacher();//注意要在这new一个新的Teacher不然list添加会重复

             t.setId(Integer.parseInt(attributes.getValue("id")));

             //System.out.println(t.getId());

         }

     }

     //读字符数据

     @Override

     public void characters(char[] ch, int start, int length)

             throws SAXException {

         if ("name".equals(flag)) {

             t.setName(new String(ch, start, length));

              //System.out.println(t.getName());

         }

     }

     //结束元素时干嘛

     @Override

     public void endElement(String uri, String localName, String qName)

             throws SAXException {

         if ("teacher".equals(qName)) {

             list.add(t);

             //System.out.println(list.get(0));

         }//System.out.println(t);

             flag = null;

     }

     //结束文件时干嘛

     @Override

     public void endDocument() throws SAXException {

         System.out.println("解析成功！");

         //System.out.println(list.get(0));

     }

     public List<Teacher> getList() {

         return list;

     }

 }

 package com.gh.xml;

 public class Teacher {

     private int id;

     private String name;

     public int getId() {

         return id;

     }

     public void setId(int id) {

         this.id = id;

     }

     public String getName() {

         return name;

     }

     public Teacher(int id, String name) {

         this.id = id;

         this.name = name;

     }

     public Teacher() {

         super();

     }

     public void setName(String name) {

         this.name = name;

     }

     @Override

     public String toString() {

         return "Teacher [id=" + id + ", name=" + name + "]";

     }

 }

 package com.gh.xml;

 import java.beans.XMLDecoder;

 import java.beans.XMLEncoder;

 import java.io.BufferedInputStream;

 import java.io.BufferedOutputStream;

 import java.io.File;

 import java.io.FileInputStream;

 import java.io.FileOutputStream;

 /**

  * xml和对象之间的转换

  * @author ganhang

  *

  */

 public class ObjectAndXmlDemo {

     /**

      * 把对象转成xml

      * @param obj

      * @param file

      * @throws Exception

      */

     public static void object2xml(Teacher obj,File file) throws Exception{

         BufferedOutputStream bos=new BufferedOutputStream(new FileOutputStream(file));

         XMLEncoder encode=new XMLEncoder(bos);

         encode.writeObject(obj);

         encode.flush();

         encode.close();

         bos.close();

         System.out.println("写入成功");

     }

     /**

      * xml转成对象

      * @param file

      * @return

      * @throws Exception

      */

     public static Teacher xml2object(File file) throws Exception{

         BufferedInputStream bis=new BufferedInputStream(new FileInputStream(file));

         XMLDecoder decode =new XMLDecoder(bis);

         Teacher t=(Teacher)decode.readObject();

         decode.close();

         bis.close();

         System.out.println("读入成功");

         return t;

     }

     public static void main(String[] args) throws Exception {

         //Teacher t=new Teacher(1,"小白");

         //object2xml(t,new File("src/2.xml"));

         System.out.println(xml2object(new File("src/2.xml")));

     }

 }

1.xml

 <?xml version="1.0" encoding="UTF-8"?>

 <person>

     <teacher id="1">

         <name>小白</name>

         <desc>hehe1</desc>

     </teacher>

     <teacher id="2">

         <name>小黑</name>

         <desc>hehe2</desc>

     </teacher>

     <teacher id="3">

         <name>小红</name>

         <desc>hehe3</desc>

     </teacher>

 </person>

2.xml

 <?xml version="1.0" encoding="UTF-8"?>

 <java version="1.7.0_79" class="java.beans.XMLDecoder">

  <object class="com.gh.xml.Teacher">

   <void property="id">

    <int>1</int>

   </void>

   <void property="name">

    <string>小白</string>

   </void>

  </object>

 </java>

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java学习之xml

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