Dom4j最常用最簡單的用法

要使用dom4j讀寫XML文檔,需要先下載dom4j包,dom4j官方網站在 http://www.dom4j.org/
目前最新dom4j包下載地址:http://nchc.dl.sourceforge.net/sourceforge/dom4j/dom4j-1.6.1.zip

解開后有兩個包,僅操作XML文檔的話把dom4j-1.6.1.jar加入工程就可以了,如果需要使用XPath的話還需要加入包jaxen-1.1-beta-7.jar.

以下是相關操作:

一.Document對象相關

1.讀取XML文件,獲得document對象.
            SAXReader reader = new SAXReader();
            Document  document = reader.read(new File("input.xml"));

2.解析XML形式的文本,得到document對象.
            String text = "<members></members>";
            Document document = DocumentHelper.parseText(text);
3.主動創建document對象.
            Document document = DocumentHelper.createDocument();
            Element root = document.addElement("members");// 創建根節點
二.節點相關

1.獲取文檔的根節點.
Element rootElm = document.getRootElement();
2.取得某節點的單個子節點.
Element memberElm=root.element("member");// "member"是節點名
3.取得節點的文字
String text=memberElm.getText();
也可以用:
String text=root.elementText("name");這個是取得根節點下的name字節點的文字.

4.取得某節點下名為"member"的所有字節點并進行遍歷.
List nodes = rootElm.elements("member");

for (Iterator it = nodes.iterator(); it.hasNext();) {
   Element elm = (Element) it.next();
   // do something
}
5.對某節點下的所有子節點進行遍歷.
            for(Iterator it=root.elementIterator();it.hasNext();){
                Element element = (Element) it.next();
                // do something
            }
6.在某節點下添加子節點.
Element ageElm = newMemberElm.addElement("age");
7.設置節點文字.
ageElm.setText("29");
8.刪除某節點.
parentElm.remove(childElm);// childElm是待刪除的節點,parentElm是其父節點
三.屬性相關.
1.取得某節點下的某屬性
            Element root=document.getRootElement();    
            Attribute attribute=root.attribute("size");// 屬性名name
2.取得屬性的文字
            String text=attribute.getText();
也可以用:
String text2=root.element("name").attributeValue("firstname");這個是取得根節點下name字節點的屬性firstname的值.

3.遍歷某節點的所有屬性
            Element root=document.getRootElement();    
            for(Iterator it=root.attributeIterator();it.hasNext();){
                Attribute attribute = (Attribute) it.next();
                String text=attribute.getText();
                System.out.println(text);
            }
4.設置某節點的屬性和文字.
newMemberElm.addAttribute("name", "sitinspring");
5.設置屬性的文字
            Attribute attribute=root.attribute("name");
            attribute.setText("sitinspring");
6.刪除某屬性
            Attribute attribute=root.attribute("size");// 屬性名name
            root.remove(attribute);
四.將文檔寫入XML文件.
1.文檔中全為英文,不設置編碼,直接寫入的形式.
XMLWriter writer = new XMLWriter(new FileWriter("output.xml"));
writer.write(document);
writer.close();
2.文檔中含有中文,設置編碼格式寫入的形式.
            OutputFormat format = OutputFormat.createPrettyPrint();
            format.setEncoding("GBK");    // 指定XML編碼        
            XMLWriter writer = new XMLWriter(new FileWriter("output.xml"),format);
            
            writer.write(document);
            writer.close();
五.字符串與XML的轉換
1.將字符串轉化為XML
String text = "<members> <member>sitinspring</member> </members>";
Document document = DocumentHelper.parseText(text);
2.將文檔或節點的XML轉化為字符串.
            SAXReader reader = new SAXReader();
            Document  document = reader.read(new File("input.xml"));            
            Element root=document.getRootElement();                
            String docXmlText=document.asXML();
            String rootXmlText=root.asXML();
            Element memberElm=root.element("member");
            String memberXmlText=memberElm.asXML();
六.使用XPath快速找到節點.
讀取的XML文檔示例
<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
  <name>MemberManagement</name>
  <comment></comment>
  <projects>
    <project>PRJ1</project>
    <project>PRJ2</project>
    <project>PRJ3</project>
    <project>PRJ4</project>
  </projects>
  <buildSpec>
    <buildCommand>
      <name>org.eclipse.jdt.core.javabuilder</name>
      <arguments>
      </arguments>
    </buildCommand>
  </buildSpec>
  <natures>
    <nature>org.eclipse.jdt.core.javanature</nature>
  </natures>
</projectDescription>

使用XPath快速找到節點project.
 public static void main(String[] args){
    SAXReader reader = new SAXReader();
    
    try{
      Document  doc = reader.read(new File("sample.xml"));
      
      List projects=doc.selectNodes("/projectDescription/projects/project");
      
      Iterator it=projects.iterator();
      
      while(it.hasNext()){
        Element elm=(Element)it.next();       
        System.out.println(elm.getText());
      }
      
    }
    catch(Exception ex){
       ex.printStackTrace();
    }

附帶一個簡單的例子

package com.stz;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import java.io.File;
import java.util.Iterator;
import java.util.List;
public class TestDate {
public static void  main(String[]args){
    String xml="<?xml version=\"1.0\" encoding=\"utf-8\"?>"+
     "<students>"+
     "   <student id=\"1\">"+
      "      <name>stz</name>"+
       "     <age>23</age>"+
        "</student>"+
        "<student id=\"2\">"+
            "<name>rhl</name>"+
            "<age>23</age>"+
        "</student>"+
        "<student id=\"3\">"+
         "   <name>tom</name>"+
          "  <age>23</age>"+
        "</student>"+
    "</students>";

try {
    Document document=DocumentHelper.parseText(xml);
    Element root=document.getRootElement();
    //System.out.println(ele.e);
    //List nodes=root.elements("student");
    //System.out.println(root.getName());
    //root.elementIterator();
    List nodes=document.selectNodes("/students/student");

    for (Iterator it = nodes.iterator(); it.hasNext();) {
        Element elm = (Element) it.next();
        System.out.println("id:"+elm.attributeValue("id"));
        System.out.println(elm.getName());
        Element eles=elm.element("name");
        System.out.println(eles.getText());
        Element elea=elm.element("age");
        System.out.println(elea.getText());
     }

} catch (DocumentException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}






}
}</pre>

來自：http://my.oschina.net/u/2434626/blog/521522