Dom4j下載及使用Dom4j讀寫XML簡介

要使用dom4j讀寫XML文檔,須要先下載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

解開後有兩個包,僅操做XML文檔的話把dom4j-1.6.1.jar加入工程就能夠了,若是須要使用XPath的話還須要加入包jaxen-1.1-beta-7.jar.

如下是相關操做:

一.Document對象相關

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

2.解析XML形式的文本,獲得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.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();
也能夠用:
String text=root.elementText("name");這個是取得根節點下的name字節點的文字.

4.取得某節點下名爲"member"的全部字節點並進行遍歷.
List nodes = rootElm.elements("member");

for (Iterator it = nodes.iterator(); it.hasNext();) {
   Element elm = (Element) it.next();
   // do something
}
5.對某節點下的全部子節點進行遍歷.
            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();
也能夠用:
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.遍歷某節點的全部屬性
            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.文檔中全爲英文,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.將字符串轉化爲XML
String text = "<members> <member>sitinspring</member> </members>";
Document document = DocumentHelper.parseText(text);
2.將文檔或節點的XML轉化爲字符串.
            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();     }   }