一.Document對象,三種創建方法

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格式的字符串,獲得document對象.
            String text = "<members></members>";
            Document document = DocumentHelper.parseText(text);
3.創建document空對象.
            Document document = DocumentHelper.createDocument();
            Element  root = document.addElement("members");// 創建根節點,只有空DOCUMENT對象才能創建ROOT結點

1.獲取文檔的根節點.
           Element   root = document.getRootElement();
2.取得節點的文本
           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;可以類推任何節點下的文本
3.設置節點文字.
           ageElm.setText("29");
4.父節點下獲得單個子節點對象.
           Element memberElm=root.element("member");  // "member"是節點名

5.取得父節點下遍歷名為"member"的所有子節點.
           List nodes = rootElm.elements("member");
           for (Iterator it = nodes.iterator(); it.hasNext();) {
                 Element elm = (Element) it.next();
                 // do something
            }
6.父節點下的遍歷所有子節點進行.
            for(Iterator it=root.elementIterator();it.hasNext();){
                Element element = (Element) it.next();
                // do something
            }
7.父節點下添加子節點.
           Element ageElm = newMemberElm.addElement("age");

8.父節點下刪除子節點.
           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");
     //Element nodes0=xmlDoc.selectSingleNode("/bookstore"); //采用相對路徑,即當前結點(包括當前結點)開始查找,與下列結果相同.
     //Element nodes=nodes0.selectNodes("book");      ////采用絕對路徑,即當前結點(包括當前結點)開始查找,
     //XPATH語法詳見: http://www.w3school.com.cn/xpath/xpath_syntax.asp

      Iterator it=projects.iterator();
     
      while(it.hasNext()){
        Element elm=(Element)it.next();      
        System.out.println(elm.getText());
      }
     
    }
    catch(Exception ex){
       ex.printStackTrace();
    }
  }