DOM4j

※xml.xml

<?xml version="1.0" encoding="UTF-8"?>
<root>top1
    top2
    <first fa="f1" fb="1f">
        first-1
        <second1 sa="s1">aaa</second1>
        <second2>bbb</second2>
        <second3>ccc</second3>
    </first>
    top3
    <first fa="f2" fb="2f">
        first-2
        <second1 sa="s2">ddd</second1>
        <second2>eee</second2>
        <second3>fff</second3>
    </first>
    top4
    <first fa="f3" fb="3f">
        first-3
        <second1 sa="s3">ggg</second1>
        <second2>hhh</second2>
        <second3>iii</second3>
    </first>
</root>

※

※maven

<dependency>
    <groupId>dom4j</groupId>
    <artifactId>dom4j</artifactId>
    <version>1.6.1</version>
</dependency>

※讀檔

import java.util.Iterator;
import java.util.List;
import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
    
public class DOM4jTest {
    public static void main(String[] args) throws DocumentException {
        SAXReader reader = new SAXReader();
        Document doc = reader.read("src/main/java/xml.xml");
        Element root = doc.getRootElement();
    
        System.out.println("方法一");
        List<Element> first = root.elements();
        for (Element e : first) {
            System.out.println(e.getText().trim());
            for (Object o : e.attributes()) {
                System.out.println(((Attribute) o).getValue());
            }
    
            System.out.println("子元素");
            List<Element> second = e.elements();
            for (Element s : second) {
                System.out.println(s.getText().trim());
            }
            System.out.println(System.getProperty("line.separator"));
        }
    
        System.out.println("方法二");
        Iterator<Element> it2 = root.elementIterator();
        while (it2.hasNext()) {
            Element firstTwo = (Element) it2.next();
            // ...
        }
    
        System.out.println("方法三");
        for (Iterator<Element> it3 = root.elementIterator(); it3.hasNext();) {
            Element firstThree = it3.next();
            // ...
        }
    }
}

※方法二和三，迴圈裡的內容和方法一一樣

※使用XPath

※要使用 XPath 必需要有 jaxen 的 jar，否則執行selectSingleNode方法時會報錯

<dependency>
    <groupId>jaxen</groupId>
    <artifactId>jaxen</artifactId>
    <version>1.1.6</version>
</dependency>

※

import java.io.IOException;
import java.util.List;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import org.dom4j.tree.DefaultAttribute;
    
public class DOM4jTest {
    public static void main(String[] args) throws IOException, DocumentException {
        SAXReader reader = new SAXReader();
        Document doc = reader.read("src/main/java/xml.xml");
        Node root = doc.selectSingleNode("/root");
        List<Element> second1 = root.selectNodes("first/second1");
    
        for (Element e : second1) {
            System.out.println(e.getName());
            System.out.println(e.getText());
            System.out.println(e.attributeValue("sa"));
            System.out.println("---------------");
        }
    
        System.out.println("===============");
        List<Element> first = root.selectNodes("first");
        for (Element e : first) {
            System.out.println(e.getName());
            System.out.println(e.getText().trim());
    
            for (Object o : e.attributes()) {
                DefaultAttribute ele = (DefaultAttribute) o;
                System.out.println(ele.getStringValue());
            }
            System.out.println("===============");
        }
    }
}

※selectSingleNode 和 selectNodes 可以寫XPath

※寫檔

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
    
public class DOM4jTest {
    public static void main(String[] args) throws IOException {
        Document doc = DocumentHelper.createDocument();
        Element root = doc.addElement("root");
        Element first = root.addElement("first");
        Element second1 = first.addElement("second1");
        Element second2 = first.addElement("second2");
        Element second3 = first.addElement("second3");
    
        root.setText("top1" + System.getProperty("line.separator") + "\ttop2");
        first.setText("first-1");
        second1.setText("aaa");
        second2.setText("bbb");
        second3.setText("ccc");
    
        first.addAttribute("fa", "f1");
        first.addAttribute("fb", "1f");
        second1.addAttribute("sa", "s1");
    
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("UTF-8");
    
        File file = new File("D:/" + File.separator + "xml.xml");
        OutputStream fout = new FileOutputStream(file, true);
        XMLWriter out = new XMLWriter(fout, format);
        out.write(doc);
        out.close();
        System.out.println("XML已生成");
    }
}

※此例只是寫其中一個first而已

※變數format是讓產生出的XML有排版