首先我們給出一段示例程序：
import java.io.File;
import java.io.FileWriter;
import java.util.Iterator;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;
public class DOM4JTest 
{
/** *//** */
/** *//** */
/** *//** */
/** *//**
* DOM4J讀寫XML示例
*
* @param args
* @throws Exception
*/
public static void main(String[] args) {
try {
XMLWriter writer = null;// 聲明寫XML的對象
SAXReader reader = new SAXReader();
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("GBK");// 設置XML文件的編碼格式
String filePath = "d:\\student.xml";
File file = new File(filePath);
if (file.exists()) {
Document document = reader.read(file);// 讀取XML文件
Element root = document.getRootElement();// 得到根節點
boolean bl = false;
for (Iterator i = root.elementIterator("學生"); i.hasNext();) {
Element student = (Element) i.next();
if (student.attributeValue("sid").equals("001")) {
// 修改學生sid=001的學生信息
student.selectSingleNode("姓名").setText("王五");
student.selectSingleNode("年齡").setText("25");
writer = new XMLWriter(new FileWriter(filePath), format);
writer.write(document);
writer.close();
bl = true;
break;
}
}
if (bl) {
// 添加一個學生信息
Element student = root.addElement("學生");
student.addAttribute("sid", "100");
Element sid = student.addElement("編號");
sid.setText("100");
Element name = student.addElement("姓名");
name.setText("嘎嘎");
Element sex = student.addElement("性別");
sex.setText("男");
Element age = student.addElement("年齡");
age.setText("21");
writer = new XMLWriter(new FileWriter(filePath), format);
writer.write(document);
writer.close();
}
} else {
// 新建student.xml文件并新增內容
Document _document = DocumentHelper.createDocument();
Element _root = _document.addElement("學生信息");
Element _student = _root.addElement("學生");
_student.addAttribute("sid", "001");
Element _id = _student.addElement("編號");
_id.setText("001");
Element _name = _student.addElement("姓名");
_name.setText("灰機");
Element _age = _student.addElement("年齡");
_age.setText("18");
writer = new XMLWriter(new FileWriter(file), format);
writer.write(_document);
writer.close();
}
System.out.println("操作結束! ");
} catch (Exception e) {
e.printStackTrace();
}
}
}
執行結果應該是這樣：
循環解析節點：
private void getAllNodes(String xml) {
try {
Document authtmp = DocumentHelper.parseText(xml);
List<Element> list = authtmp.selectNodes("//sms/node");
for (int j = 0; j < list.size(); j++) {
Element node = (Element) list.get(j);
nodeByNodes(node);
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void nodeByNodes(Element node) {
if (node.element("node") != null) {
String id = node.attributeValue("id");
String name = node.attributeValue("name");
System.out.print(id + "-------");
System.out.println(name);
for (Iterator i = node.elementIterator("node"); i.hasNext();) {
Element newNode = (Element) i.next();
nodeByNodes(newNode);
}
} else {
String id = node.attributeValue("id");
String name = node.attributeValue("name");
System.out.print(id + "-------");
System.out.println(name);
}
}
其次DOM4J的解釋
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
9.添加一個CDATA節點.
Element contentElm = infoElm.addElement("content");
contentElm.addCDATA(diary.getContent());
contentElm.getText(); // 特別說明：獲取節點的CDATA值與獲取節點的值是一個方法
contentElm.clearContent(); //清除節點中的內容，CDATA亦可
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();