java修改xml文件中某个属性值

你可以使用Java的DOM解析器来修改XML文件中的某个属性值。具体步骤如下：

1. 加载XML文件并创建DOM文档对象。

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new File("example.xml"));

2. 获取需要修改的元素节点。

Element root = doc.getDocumentElement();
NodeList nodeList = root.getElementsByTagName("book");
Element bookElement = null;
for (int i = 0; i < nodeList.getLength(); i++) {
    Element element = (Element) nodeList.item(i);
    String id = element.getAttribute("id");
    if (id.equals("001")) {
        bookElement = element;
        break;
    }
}

3. 修改属性值。

bookElement.setAttribute("price", "19.99");

4. 将修改后的DOM文档写入XML文件。

TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File("example.xml"));
transformer.transform(source, result);

完整代码示例：

import java.io.File;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

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

            Element root = doc.getDocumentElement();
            NodeList nodeList = root.getElementsByTagName("book");
            Element bookElement = null;
            for (int i = 0; i < nodeList.getLength(); i++) {
                Element element = (Element) nodeList.item(i);
                String id = element.getAttribute("id");
                if (id.equals("001")) {
                    bookElement = element;
                    break;
                }
            }

            bookElement.setAttribute("price", "19.99");

            TransformerFactory transformerFactory = TransformerFactory.newInstance();
            Transformer transformer = transformerFactory.newTransformer();
            DOMSource source = new DOMSource(doc);
            StreamResult result = new StreamResult(new File("example.xml"));
            transformer.transform(source, result);

            System.out.println("XML file updated successfully");

        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}