Java DOM解析XML筛选supplier为Apple的product节点方法

现有一份订单XML文件，需要提取所有<supplier>子节点值为Apple的<product>节点内容。初始编写的Java代码存在逻辑错误，无法得到预期结果。
测试用XML内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<orders>
    <order created='2012-07-12T15:29:33.000' ID='2343'>
        <product>
            <description>Sony 54.6" (Diag) Xbr Hx929 Internet Tv</description>
            <gtin>00027242816657</gtin>
            <price currency="USD">2999.99</price>
            <supplier>Sony</supplier>
        </product>
        <product>
            <description>Apple iPad 2 with Wi-Fi 16GB - iOS 5 - Black</description>
            <gtin>00885909464517</gtin>
            <price currency="USD">399.0</price>
            <supplier>Apple</supplier>
        </product>
        <product>
            <description>Sony NWZ-E464 8GB E Series Walkman Video MP3 Player Blue</description>
            <gtin>00027242831438</gtin>
            <price currency="USD">91.99</price>
            <supplier>Sony</supplier>
        </product>
    </order>
    <order created='2012-07-13T16:02:22.000' ID='2344'>
        <product>
            <description>Apple MacBook Air A 11.6" Mac OS X v10.7 Lion MacBook</description>
            <gtin>00885909464043</gtin>
            <price currency="USD">1149.0</price>
            <supplier>Apple</supplier>
        </product>
        <product>
            <description>Panasonic TC-L47E50 47" Smart TV Viera E50 Series LED HDTV</description>
            <gtin>00885170076471</gtin>
            <price currency="USD">999.99</price>
            <supplier>Panasonic</supplier>
        </product>
    </order>
</orders>

• 节点选取错误：初始代码直接选取根节点<orders>，没有定位到目标<product>节点
• 元素属性混淆：<supplier>是<product>下的子元素，不是节点属性，用属性读取的方式无法获取对应值
• 路径转义错误：Windows路径中的反斜杠没有做转义处理，会被Java识别为非法转义字符，导致文件读取失败

import org.w3c.dom.*;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import java.io.File;
import java.io.IOException;
import java.io.StringWriter;

public class XmlProductParser {
    public void readXml() throws ParserConfigurationException, SAXException, IOException, TransformerException {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = dbf.newDocumentBuilder();
        // 路径推荐用正斜杠，不需要额外转义，避免转义符错误
        Document doc = builder.parse(new File("C:/Users/40723/Documents/NetBeansProjects/SACOM/src/sacom/suppliers23.xml"));
        // 直接获取所有product节点列表
        NodeList productList = doc.getElementsByTagName("product");

        for (int i = 0; i < productList.getLength(); i++) {
            Node productNode = productList.item(i);
            // 跳过空白、注释等非元素节点
            if (productNode.getNodeType() != Node.ELEMENT_NODE) {
                continue;
            }
            Element productEle = (Element) productNode;
            // 读取当前product下supplier节点的文本值
            String supplierVal = productEle.getElementsByTagName("supplier").item(0).getTextContent().trim();
            // 匹配供应商为Apple的商品
            if ("Apple".equals(supplierVal)) {
                System.out.println("匹配到Apple供应商商品：");
                // 输出当前product节点的完整XML内容
                TransformerFactory tf = TransformerFactory.newInstance();
                Transformer transformer = tf.newTransformer();
                transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                transformer.setOutputProperty(OutputKeys.INDENT, "yes");
                StringWriter writer = new StringWriter();
                transformer.transform(new DOMSource(productNode), new StreamResult(writer));
                System.out.println(writer.getBuffer().toString());
                System.out.println("--------------------");
            }
        }
    }

    public static void main(String[] args) throws Exception {
        new XmlProductParser().readXml();
    }
}

代码执行后会输出2个匹配结果，分别对应Apple iPad 2、Apple MacBook Air两个商品的完整product节点内容。如果不需要输出完整XML，也可以直接通过getElementsByTagName方法分别读取description、gtin、price等子节点的值，做后续业务处理。

内容的提问来源于stack exchange，提问作者JohnNewman