XML简介

1. 什么是XML

请先下载附录中的dom4j文件

2. XML格式

3. XML标签

4. XML编写注意事项

5. 转义符⭐

6. 解析XML

7. 常用接口介绍

8. 访问DOM树节点

9. 保存XML文件

10. 范例代码：包含（显示/添加/删除/修改）

XML文件

<?xml version="1.0" encoding="UTF-8"?>
<scoreInfo><sport name="王贤明" id="1001"><expectScore>预计得分75</expectScore><realScore>实际得分80</realScore></sport><sport name="宋佳" id="1002"><expectScore>预计得分75</expectScore><realScore>实际得分88</realScore></sport>
</scoreInfo>

应用代码

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 java.io.FileWriter;
import java.io.IOException;
import java.util.Iterator;public class dom4jParse {private Document doc;/*** 加载文件转换成dom4j的文档对象*/public void loadDocument() throws DocumentException {//读取xml文件的对象SAXReader saxReader = new SAXReader();//读取文件， 将读取的内容转换成document对象doc = saxReader.read("src/c05/score.xml");}//将添加/删除/修改操作写入XML文件==========================================public void addScoreInfo() throws IOException {//创建xml格式的Output对象OutputFormat outputFormat = new OutputFormat();//创建文件写入的对象FileWriter fileWriter = new FileWriter("src/c05/score.xml");//将文件写入的格式转换为xml格式XMLWriter xmlWriter = new XMLWriter(fileWriter,outputFormat);//写入文件docxmlWriter.write(doc);//关闭流xmlWriter.close();fileWriter.close();}/*** 获取xml文件中存储的数据*/public void show(){//获取根节点Element root = doc.getRootElement();System.out.println("根节点："+root.getName());System.out.println("=====================================");//根元素下有多个子元素Iterator<Element> it = root.elementIterator();while (it.hasNext()){//获取第i个元素<sport>Element sport = it.next();System.out.println("元素名称："+sport.getName());//获取id 和name的属性值String name = sport.attributeValue("name");String id = sport.attributeValue("id");System.out.println("运动员："+name+",ID："+id);//获取<expectScore> 和 <realScore>元素值Element expectScoreElement = sport.element("expectScore");Element realScoreElement = sport.element("realScore");//获取<expectScore> 和 <realScore>元素里的文本String expectScore = expectScoreElement.getText();String realScore = realScoreElement.getText();System.out.println(expectScore+","+realScore);System.out.println("=====================================");}}//添加XML文件中的元素==========================================public void addSport() throws IOException {//获取根节点Element root = doc.getRootElement();//添加子元素和子元素的属性Element sportElement = root.addElement("sport");sportElement.addAttribute("name","张三");sportElement.addAttribute("id","1003");//添加子元素的元素<expectScore>、<realScore>和<expectScore>、<realScore>元素内的文本信息Element expectScoreElement = sportElement.addElement("expectScore");expectScoreElement.setText("预计得分70");Element realScoreElement = sportElement.addElement("realScore");realScoreElement.setText("实际得分95");//调用写入方法addScoreInfo();}//删除XML文件中的元素==========================================public void deleteSport() throws IOException {//获取根节点Element root = doc.getRootElement();//根元素下有多个子元素Iterator<Element> it = root.elementIterator();while (it.hasNext()) {Element sportElement=it.next();//获取属性id为1003的子元素String id=sportElement.attributeValue("id");if (id.equals("1003")){//删除根节点下的该元素root.remove(sportElement);}}//调用写入方法addScoreInfo();}//修改XML文件中的元素==========================================public void modifySport() throws IOException {//获取根节点Element root = doc.getRootElement();//根元素下有多个子元素Iterator<Element> it = root.elementIterator();while (it.hasNext()) {Element sportElement=it.next();//获取属性id为1003的子元素String id=sportElement.attributeValue("id");if (id.equals("1003")){//获取子元素的元素<expectScore>、<realScore>，将<expectScore>、<realScore>元素内的文本信息替换Element expectScoreElement = sportElement.element("expectScore");expectScoreElement.setText("预计得分60");Element realScoreElement = sportElement.element("realScore");realScoreElement.setText("实际得分70");}}//调用写入方法addScoreInfo();}
}

1. 显示

import org.dom4j.DocumentException;import java.io.IOException;public class TestScore {public static void main(String[] args) throws DocumentException, IOException {dom4jParse dom4jParse = new dom4jParse();dom4jParse.loadDocument();dom4jParse.show();}
}

运行结果：

2. 添加

添加一个元素，姓名张三，ID1003，预计得分70，实际得分95

import org.dom4j.DocumentException;import java.io.IOException;public class TestScore {public static void main(String[] args) throws DocumentException, IOException {dom4jParse dom4jParse = new dom4jParse();dom4jParse.loadDocument();dom4jParse.addSport();dom4jParse.show();}
}

运行结果：

在XML文件中：

3. 删除

根据1003这个ID来删除这个元素

import org.dom4j.DocumentException;import java.io.IOException;public class TestScore {public static void main(String[] args) throws DocumentException, IOException {dom4jParse dom4jParse = new dom4jParse();dom4jParse.loadDocument();dom4jParse.deleteSport();dom4jParse.show();}
}

运行结果：

在XML文件中：

4. 修改

根据1003这个ID来修改预计得分为60，实际得分为70

import org.dom4j.DocumentException;import java.io.IOException;public class TestScore {public static void main(String[] args) throws DocumentException, IOException {dom4jParse dom4jParse = new dom4jParse();dom4jParse.loadDocument();dom4jParse.modifySport();dom4jParse.show();}
}

显示结果：