xml文件解析-JDOM

1.构造解析器

方法1：

import org.jdom.*;
import org.jdom.input.*;

SAXBuilder saxBuilder = new SAXBuilder();
File file = new File("src/c03/students.xml");
Document doc = saxBuilder.build(file);

方法2：

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
File file = new File("src/c03/students.xml");
org.w3c.dom.Document doc = db.parse(file);
DOMBuilder domBuilder = new DOMBuilder ();
org.jdom.Document doc = domBuilder.build(doc);


2.jdom函数

(1)创建xml文档

Document doc = new Document();

Element eltRoot = new Element("student");

doc.setRootElement(eltRoot);

(2)添加元素和属性

Element eltStu = new Element("student");
Element eltName = new Element("name");
Element eltAge = new Element("age");

eltName.setText("王五");
eltAge.setText("19");

eltStu.addContent(eltName);
eltStu.addContent(eltAge);

eltStu.setAttribute("sn", "03");

(3)访问元素

访问根元素： Element root = doc.getRootElement();

得到某元素下所有子元素：LIst children = element.getChildren();

得到指定元素下所有子元素：LIst children = element.getChildren("student");

得到指定元素的第一个子元素：Element child = element.getChild("student");

返回指定子节点的内容文本值： getChildText("childname")

返回该元素的内容文本值：getText()

取得元素的子元素（为最低层元素）的值：String name=book.getChildTextTrim("name");

(4)访问属性

得到指定元素下所有属性：List attrList = element.getAttributes();

得到指定属性：Attribute attr = element.getAttribute("sn");

得到指定属性的值：String attrValue = element.getAttributeValue("sn");

(5)删除元素和属性

删除指定元素下所有子元素：element.removeChildren("student");

删除指定元素下第一个子元素：element.removeChild("student");

删除指定属性：element.removeAttribute("sn");

(6)输出文档
XMLOutputter xmlOut = new XMLOutputter();
Format fmt = Format.getPrettyFormat();
fmt.setEncoding("GB2312");
fmt.setIndent(" ");
xmlOut.setFormat(fmt);
xmlOut.output(doc, new FileOutputStream("src/c03/students.xml"));

或者输出到xmlOut.output(doc, System.out);

3.JDOM实例

import java.io.*;

import org.jdom.*;
import org.jdom.input.*;
import org.jdom.output.*;

public class JDOMConvert {

/**
* @param args
*/
public static void main(String[] args) {
SAXBuilder saxBuilder = new SAXBuilder();
File file = new File("src/c03/students.xml");
try {
Document doc = saxBuilder.build(file);

// add element
Element eltStu = new Element("student");
Element eltName = new Element("name");
Element eltAge = new Element("age");

eltName.setText("王五");
eltAge.setText("19");

eltStu.addContent(eltName);
eltStu.addContent(eltAge);

eltStu.setAttribute("sn", "03");

Element root = doc.getRootElement();
root.addContent(eltStu);

// remove element
root.removeChild("student");

// modify element
root.getChild("student").getChild("age").setText("23");

// output to screen
XMLOutputter xmlOut = new XMLOutputter();
Format fmt = Format.getPrettyFormat();
fmt.setEncoding("GB2312");
fmt.setIndent(" ");
xmlOut.setFormat(fmt);
xmlOut.output(doc, new FileOutputStream("src/c03/students.xml"));
}
catch (IOException e) {
System.out.println(e.getMessage());
}
catch (JDOMException e) {
System.out.println(e.getMessage());
}

}
}