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>