dom4j解析xml
现在有很多工具包可以解析xml文件,但是dom4j无疑是其中较为简单的一种,下面就用一个例子来实际操作一下:
首先得导入dom4j.jar这个夹包(网上一搜一大片)
1.随便在一个地方建立一个user.xml文件,我这儿是建立在d盘根目录下:
- <?xml version="1.0" encoding="UTF-8"?>
- <users>
- <user username="lisi" password="123"/>
- <user username="张三" password="123"/>
- <user username="zhangsan" password="123"/>
- </users>
<?xml version="1.0" encoding="UTF-8"?> <users> <user username="lisi" password="123"/> <user username="张三" password="123"/> <user username="zhangsan" password="123"/> </users>
2.对该文件进行模拟查询用户(按姓名查询)和添加用户:
- package com.easyteam.dao;
- import java.io.FileNotFoundException;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.io.OutputStream;
- import java.io.OutputStreamWriter;
- import java.io.UnsupportedEncodingException;
- import org.dom4j.Document;
- import org.dom4j.DocumentException;
- import org.dom4j.Element;
- import org.dom4j.io.OutputFormat;
- import org.dom4j.io.SAXReader;
- import org.dom4j.io.XMLWriter;
- import com.easyteam.domain.User;
- public class Userdao {
- String path="d://user.xml";
- public User findByName(String username){
- SAXReader red=new SAXReader();//创建解析器
- try {
- Document doc=red.read(path);//得到documet对象
- Element el=(Element) doc.selectSingleNode("//user[@username='"+username+"']");//查询条件,其中//表示无限深度查询,[]中放入是查询条件
- if(el==null) return null;
- String attUsername=el.attributeValue("username");//得到username这个属性的值
- String attPassword=el.attributeValue("password");
- User user=new User();
- user.setUsername(attUsername);
- user.setPassword(attPassword);
- return user;
- } catch (DocumentException e) {
- throw new RuntimeException(e);
- }
- }
- public void addUser(User user){
- SAXReader red=new SAXReader();
- try {
- Document doc = red.read(path);
- Element attroot=doc.getRootElement();//得到根节点
- Element userel=attroot.addElement("user");//添加节点
- userel.addAttribute("username", user.getUsername());//给新节点赋值
- userel.addAttribute("password", user.getPassword());
- OutputFormat format=new OutputFormat("\t", true);//设置格式
- format.setTrimText(true);//清除原有格式
- XMLWriter writer;
- try {
- writer=new XMLWriter(new OutputStreamWriter(new FileOutputStream(path),"utf-8"),format);//实例化
- writer.write(doc);//保存
- writer.close();
- } catch (Exception e) {
- throw new RuntimeException(e);
- }
- } catch (DocumentException e) {
- throw new RuntimeException(e);
- }
- }
- }
3.测试类:
- package com.easyteam.test;
- import org.junit.Test;
- import com.easyteam.dao.Userdao;
- import com.easyteam.domain.User;
- public class UserDaoTest {
- @Test
- public void testfindByName(){
- Userdao dao=new Userdao();
- User user= dao.findByName("lisi");
- System.out.println(user);
- }
- @Test
- public void testaddUser(){
- Userdao dao=new Userdao();
- User user=new User();
- user.setUsername("张三");
- user.setPassword("123");
- dao.addUser(user);
- }
- }