dom4j的使用流程和常用方法

要使用dom4j讀寫XML文檔,需要先下載下傳dom4j包,dom4j官方網站在 http://www.dom4j.org/

目前最新dom4j包下載下傳位址:http://nchc.dl.sourceforge.net/sourceforge/dom4j/dom4j-1.6.1.zip

解開後有兩個包,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檔案,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.主動建立document對象.

            Document document = DocumentHelper.createDocument();

            Element root = document.addElement("members");// 建立根節點

二.節點相關

1.擷取文檔的根節點.

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位元組點的文字.

4.取得某節點下名為"member"的所有位元組點并進行周遊.

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周遊.

            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.設定節點文字.

ageElm.setText("29");

8.删除某節點.

parentElm.remove(childElm);// childElm是待删除的節點,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();

String text2=root.element("name").attributeValue("firstname");這個是取得根節點下name位元組點的屬性firstname的值.

3.周遊某節點的所有屬性

            for(Iterator it=root.attributeIterator();it.hasNext();){

                Attribute attribute = (Attribute) it.next();

                String text=attribute.getText();

                System.out.println(text);

4.設定某節點的屬性和文字.

newMemberElm.addAttribute("name", "sitinspring");

5.設定屬性的文字

            Attribute attribute=root.attribute("name");

            attribute.setText("sitinspring");

6.删除某屬性

            root.remove(attribute);

四.将文檔寫入XML檔案.

1.文檔中全為英文,不設定編碼,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,設定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.字元串與XML的轉換

1.将字元串轉化為XML

String text = "<members> <member>sitinspring</member> </members>";

Document document = DocumentHelper.parseText(text);

2.将文檔或節點的XML轉化為字元串.

            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();

代碼示例：

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();
    }

  }
}