首先我們給出一段示例程式：
1.讀取XML檔案,獲得document對象.
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
{
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");// 設定XML檔案的編碼格式
String filePath = "d://student.xml";
File file = new File(filePath);
if (file.exists())
{
Document document = reader.read(file);// 讀取XML檔案
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的學生資訊
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)
{
// 添加一個學生資訊
Element student = root.addElement("學生");
student.addAttribute("sid", "100");
Element sid = student.addElement("編号");
sid.setText("100");
Element name = student.addElement("姓名");
name.setText("嘎嘎");
Element sex = student.addElement("性别");
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
{
// 建立student.xml檔案并新增内容
Document _document = DocumentHelper.createDocument();
Element _root = _document.addElement("學生資訊");
Element _student = _root.addElement("學生");
_student.addAttribute("sid", "001");
Element _id = _student.addElement("編号");
_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
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
9.添加一個CDATA節點.
Element contentElm = infoElm.addElement( " content " );
contentElm.addCDATA(diary.getContent());
contentElm.getText(); // 特别說明：擷取節點的CDATA值與擷取節點的值是一個方法
contentElm.clearContent(); //清除節點中的内容，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位元組點的屬性firstname的值.
3.周遊某節點的所有屬性
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
Attribute attribute = root.attribute( " size " ); // 屬性名name
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.
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();