学步园

一、DOM4J解析xml步骤

１、读取并解析XML文档，创建document对象

第一种方式可以从xml文件中读取内容，创建document对象

    SAXReader reader = new SAXReader();<br /> Document document = reader.read(new File(fileName));

第二种方式直接根据xml字符串(比如通过webservice调用后台接口返回的应答字符串)创建document对象

    docuemnt=DocumentHelper.parseText(str);

２、取得Root节点   

    读取后的第二步，就是得到Root节点。熟悉XML的人都知道，一切XML分析都是从Root元素开始的。

    Element root=doc.getRootElement();

３、遍历XML树

    一般可以由根节点构造迭代器，通过迭代器来访问其元素

for ( Iterator i = root.elementIterator(); i.hasNext(); ) {<br /> 　　Element element = (Element) i.next();<br /> System.out.println(element.getText());<br /> }

二、代码演示

首先要将dom4j的jar包导入工程的lib下

1、xml文档

<?xml version="1.0" encoding="utf-8" ?><br /> <books><br /> <book id="1"><br /> <name>A</name><br /> <number>10</number><br /> </book><br /> <book id="2"><br /> <name>B</name><br /> <number>20</number><br /> </book><br /> <book id="3"><br /> <name>C</name><br /> <number>30</number><br /> </book><br /> <book id="4"><br /> <name>D</name><br /> <number>40</number><br /> </book><br /> </books>

2、java代码

 MyDom4j.java

import java.io.BufferedReader;<br /> import java.io.ByteArrayInputStream;<br /> import java.io.File;<br /> import java.io.FileInputStream;<br /> import java.io.FileReader;<br /> import java.io.FileWriter;<br /> import java.io.IOException;<br /> import java.io.InputStream;<br /> import java.io.InputStreamReader;<br /> import java.util.Iterator;<br /> import org.dom4j.Document;<br /> import org.dom4j.DocumentException;<br /> import org.dom4j.DocumentHelper;<br /> import org.dom4j.Element;<br /> import org.dom4j.io.SAXReader;<br /> public class MyDom4j {<br /> /**<br /> * @param args<br /> * @throws Exception<br /> */<br /> public static void main(String[] args) throws Exception {<br /> //创建document对象<br /> Document d=createDC();<br /> //将生成的xml文档的内容用输出流写入文件a.xml中<br /> try {<br /> FileWriter fw=new FileWriter(new File("src/a.xml"));<br /> fw.write(d.asXML());<br /> fw.flush();<br /> fw.close();<br /> } catch (IOException e) {<br /> // TODO Auto-generated catch block<br /> e.printStackTrace();<br /> }<br /> //根据从a.xml文件的内容生成document对象,DocumentHelper.parseText这个方法会抛出DucumentException异常<br /> Document docuemnt=null;<br /> try {<br /> SAXReader sax=new SAXReader();<br /> docuemnt=sax.read(new File("src/a.xml"));<br /> } catch (DocumentException e) {<br /> // TODO Auto-generated catch block<br /> e.printStackTrace();<br /> }<br /> //得到books下子节点的迭代器<br /> Iterator it1=docuemnt.getRootElement().elementIterator();<br /> int i=0,j=0;<br /> CRSet cr=null;<br /> while(it1.hasNext()){<br /> Element child=(Element)it1.next();<br /> //得到book下子节点的迭代器<br /> Iterator it2=child.elementIterator();<br /> if(i==0&&child.elements()!=null){<br /> cr=new CRSet(child.elements().size());<br /> }<br /> cr.AddRow();<br /> while(it2.hasNext()){<br /> Element e=(Element)it2.next();<br /> String name=e.getName();<br /> String value=e.getText();<br /> cr.SetValue(i, j++, value);<br /> }<br /> i++;<br /> j=0;<br /> }</p> <p> //输出CRSet中的内容<br /> print(cr);<br /> }</p> <p> //创建DOM4J documet对象<br /> public static Document createDC(){<br /> Document d=DocumentHelper.createDocument();<br /> Element books=d.addElement("books");</p> <p> Element book1= books.addElement("book");<br /> book1.addAttribute("id", "1");<br /> Element name1=book1.addElement("name");<br /> name1.addText("A");<br /> Element number1=book1.addElement("number");<br /> number1.addText("10");</p> <p> Element book2= books.addElement("book");<br /> book2.addAttribute("id", "2");<br /> Element name2=book2.addElement("name");<br /> name2.addText("B");<br /> Element number2=book2.addElement("number");<br /> number2.addText("20");</p> <p> Element book3= books.addElement("book");<br /> book3.addAttribute("id", "3");<br /> Element name3=book3.addElement("name");<br /> name3.addText("C");<br /> Element number3=book3.addElement("number");<br /> number3.addText("30");</p> <p> Element book4= books.addElement("book");<br /> book4.addAttribute("id", "4");<br /> Element name4=book4.addElement("name");<br /> name4.addText("D");<br /> Element number4=book4.addElement("number");<br /> number4.addText("40");</p> <p> d.setXMLEncoding("utf-8");<br /> return d;<br /> }<br /> //打印CRSet对象中的数据<br /> public static void print(CRSet cr) throws Exception{<br /> if(cr!=null&&cr.getData().size()>0){<br /> for(int i=0;i<cr.GetRowCount();i++)<br /> for(int j=0;j<cr.GetColumnCount();j++){<br /> System.out.println("CRSet["+i+","+j+"]="+cr.GetValue(i, j));<br /> }<br /> }<br /> }<br /> }<br />

CRSet.java(这个类比较有用，用来存放从xml解析之后的内容)

import java.util.Iterator;<br /> import java.util.Vector;<br /> public class CRSet{<br /> private int m_Cols= 1;<br /> private int m_Rows= 0;<br /> private Vector m_Data = new Vector();<br /> public int GetColumnCount(){<br /> return m_Cols;<br /> }<br /> public int GetRowCount(){<br /> return m_Rows;<br /> }</p> <p> public CRSet(){}</p> <p> public CRSet(int cols) throws Exception{</p> <p> if(cols <= 0 || cols>=1024)<br /> {<br /> throw new Exception("SRVC009T:Illegal range of column or row."+cols);<br /> }<br /> m_Cols = cols;<br /> m_Rows = 0;</p> <p> }</p> <p> public int AddRow()<br /> {<br /> for(int i=0; i<m_Cols; i++)<br /> {<br /> m_Data.add("");<br /> }<br /> return m_Rows++;<br /> }<br /> public void SetValue(int row, int col, String value) throws Exception<br /> {<br /> if(row >= m_Rows || col >= m_Cols)<br /> {<br /> throw new Exception("SRVC009T:Illegal range of column or row."<br /> + row + "," + col);<br /> }<br /> m_Data.set(row*m_Cols+col,value);<br /> }<br /> public String GetValue(int row, int col) throws Exception<br /> {<br /> if(row >= m_Rows || col >= m_Cols)<br /> {<br /> throw new Exception("SRVC009T:Illegal range of column or row."<br /> + row + "," + col);<br /> }</p> <p> return (String)m_Data.elementAt(row*m_Cols+col);<br /> }<br /> public Vector getData(){<br /> return m_Data;<br /> }</p> <p> public Iterator iterator() {<br /> return m_Data.iterator();<br /> }</p> <p>}

3、MyDom4j .java运行之后的结果

CRSet[0,0]=A<br /> CRSet[0,1]=10<br /> CRSet[1,0]=B<br /> CRSet[1,1]=20<br /> CRSet[2,0]=C<br /> CRSet[2,1]=30<br /> CRSet[3,0]=D<br /> CRSet[3,1]=40

希望今天写的对大家有所帮助，第一次发表博客，错误在所难免，哪位大虾如果发现了错误请指出来，共同进步，谢谢！