java使用DOM读取XML数据

使用DOM（文档对象模型）读取XML数据需要以下步骤：

1. 创建DocumentBuilderFactory实例

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

2. 创建DocumentBuilder实例

DocumentBuilder builder = factory.newDocumentBuilder();

3. 解析XML文件并返回Document对象

Document document = builder.parse(new File("example.xml"));

4. 获取根节点

Element rootElement = document.getDocumentElement();

5. 遍历子节点获取需要的信息

NodeList nodeList = rootElement.getElementsByTagName("book");
for (int i = 0; i < nodeList.getLength(); i++) {
    Node node = nodeList.item(i);
    if (node.getNodeType() == Node.ELEMENT_NODE) {
        Element element = (Element) node;
        String title = element.getElementsByTagName("title").item(0).getTextContent();
        String author = element.getElementsByTagName("author").item(0).getTextContent();
        String price = element.getElementsByTagName("price").item(0).getTextContent();
        System.out.println("Title: " + title);
        System.out.println("Author: " + author);
        System.out.println("Price: " + price);
    }
}

完整代码示例：

import java.io.File;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class XMLReader {

    public static void main(String[] args) {
        try {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document document = builder.parse(new File("example.xml"));
            Element rootElement = document.getDocumentElement();

            NodeList nodeList = rootElement.getElementsByTagName("book");
            for (int i = 0; i < nodeList.getLength(); i++) {
                Node node = nodeList.item(i);
                if (node.getNodeType() == Node.ELEMENT_NODE) {
                    Element element = (Element) node;
                    String title = element.getElementsByTagName("title").item(0).getTextContent();
                    String author = element.getElementsByTagName("author").item(0).getTextContent();
                    String price = element.getElementsByTagName("price").item(0).getTextContent();
                    System.out.println("Title: " + title);
                    System.out.println("Author: " + author);
                    System.out.println("Price: " + price);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}