Question

我有一个像这样的xml：

<div class="row mt-5">
<div class="col-lg-cus col-6">
    <div class="product-box lazyload-wrap">
        <div class="remove-wishlist" data-id="7080">
            <i class="fa fa-times" aria-hidden="true"></i>
        </div>
        <div class="productAvatar">
            <a href="/vi/classic-fullface-royal-m18" title="Classic FULLFACE ROYAL M18">
                <div class="img img-background text-left origin product-img lazy-bg-img lazyload-item" style="background-image:url('/Uploads/default-image.jpg')" alt="Classic FULLFACE ROYAL M18" data-pil-src="https://fanfan.vn/Uploads/t/fa/fanfan0non-bao-hiem-cafe-racer-classic-fullface-royal-m18-5_0061169_235.jpg">
                </div>
            </a>
            <a class="btn btnQuickView "
               onclick="OpenCustomBootstrapModal('/vi/_Details?productId=7080', null, 1000, 'productPopup')">
                <span class="txtOutOfStock">Hết h&#224;ng</span>
                <span class="txtQuickView">Xem nhanh</span>
            </a>
        </div>
        <p class="mb-1 brand-name">
            <a href="/vi/royal-helmet" class="a-black" title="ROYAL HELMET">ROYAL HELMET</a>
        </p>
        <p class="name text-uppercase mb-0">
            <a href="/vi/classic-fullface-royal-m18" class="a-black">Classic FULLFACE ROYAL M18</a>
        </p>
        <div class="rating my-2">
            <span class="star-raty" data-score="0" data-readOnly="true"></span>
        </div>
        <p>
            <span>1.100.000 ₫</span>
        </p>
    </div>
</div>
<div class="col-lg-cus col-6">
    <div class="product-box lazyload-wrap">
        <div class="remove-wishlist" data-id="6855">
            <i class="fa fa-times" aria-hidden="true"></i>
        </div>
        <div class="productAvatar">
            <a href="/vi/non-bao-hiem-34-royal-m01-tem" title="N&#243;n bảo hiểm 3/4 Royal M01 Tem">
                <div class="img img-background text-left origin product-img lazy-bg-img lazyload-item" style="background-image:url('/Uploads/default-image.jpg')" alt="N&#243;n bảo hiểm 3/4 Royal M01 Tem" data-pil-src="https://fanfan.vn/Uploads/t/fa/fanfan0mu-non-bao-hiem-3-4-di-xe-may-royal-m01-tem-helmet-with-texture-4-do-xam-red-si_0060108_235.jpg">
                </div>
            </a>
            <a class="btn btnQuickView "
               onclick="OpenCustomBootstrapModal('/vi/_Details?productId=6855', null, 1000, 'productPopup')">
                <span class="txtOutOfStock">Hết h&#224;ng</span>
                <span class="txtQuickView">Xem nhanh</span>
            </a>
        </div>
        <p class="mb-1 brand-name">
            <a href="/vi/royal-helmet" class="a-black" title="ROYAL HELMET">ROYAL HELMET</a>
        </p>
        <p class="name text-uppercase mb-0">
            <a href="/vi/non-bao-hiem-34-royal-m01-tem" class="a-black">N&#243;n bảo hiểm 3/4 Royal M01 Tem</a>
        </p>
        <div class="rating my-2">
            <span class="star-raty" data-score="0" data-readOnly="true"></span>
        </div>
        <p>
            <span>400.000 ₫</span>
        </p>
    </div>
</div>

我试图解析它们，从中获取一些数据并将其解析为jaxb，这是我的操作方式：

 public static void fetchFanFanData(String dataFilePath, String type) {
    try {
        Document doc = DocParser(dataFilePath);
        XPath xpath = getXPath();

        String query = "//div[@class=\"col-lg-cus col-6\"]";
        NodeList list = (NodeList) xpath.evaluate(query, doc, XPathConstants.NODESET);
        NodeList list = doc.getDocumentElement().getChildNodes();
        System.out.println(list.getLength());

        Products products = new Products();
        for (int i = 0; i < list.getLength(); i++) {
            Node node = list.item(i);
            String url = xpath.evaluate("//p[@class=\"name text-uppercase mb-0\"]/a/@href", node, XPathConstants.STRING).toString();
            String name = xpath.evaluate("//p[@class=\"name text-uppercase mb-0\"]/a", node, XPathConstants.STRING).toString();
            String producer = xpath.evaluate("//p[@class=\"mb-1 brand-name\"]", node, XPathConstants.STRING).toString();
            String image_url = xpath.evaluate("//div[@class=\"productAvatar\"]/a/div/@data-pil-src", node, XPathConstants.STRING).toString();
            String price = xpath.evaluate("//p/span", node, XPathConstants.STRING).toString();
            Product product = new Product();
            product.setName(name);
            product.setImage(image_url);
            product.setUrl(url);
            product.setPrice(price);
            product.setProducer(producer);
            product.setStore("FanFan");
            product.setType(type);

            products.getProduct().add(product);
        }
        marshallJAXB(products, dataFilePath);
    } catch (ParserConfigurationException | SAXException | IOException | XPathExpressionException | JAXBException ex) {
        Logger.getLogger(XMLUtilities.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private static void marshallJAXB(Products products, String path) throws JAXBException, FileNotFoundException {
    JAXBContext context = JAXBContext.newInstance(Products.class);
    Marshaller m = context.createMarshaller();
    m.setProperty(Marshaller.JAXB_ENCODING, "UTF-8");
    m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
    m.marshal(products, new File(ServletActionContext.getServletContext().getRealPath("/" + "WEB-INF\\result.xml")));
}

public static XPath getXPath() {
    XPathFactory factory = XPathFactory.newInstance();
    XPath xPath = factory.newXPath();
    return xPath;
}

public static Document DocParser(String filePath)
        throws ParserConfigurationException, SAXException, IOException {
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    Document doc = builder.parse(filePath);
    return doc;
}

编组人员只是要验证jaxb是否正确，但是我得到的总是这样的第一个节点：

<products xmlns="http://www.example.org/product">
<product type="helmet">
    <name>Classic FULLFACE ROYAL M18</name>
    <url>/vi/classic-fullface-royal-m18</url>
    <image>https://fanfan.vn/Uploads/t/fa/fanfan0non-bao-hiem-cafe-racer-classic-fullface-royal-m18-5_0061169_235.jpg</image>
    <price>1.100.000 ₫</price>
    <producer>ROYAL HELMET</producer>
    <store>FanFan</store>
</product>
<product type="helmet">
    <name>Classic FULLFACE ROYAL M18</name>
    <url>/vi/classic-fullface-royal-m18</url>
    <image>https://fanfan.vn/Uploads/t/fa/fanfan0non-bao-hiem-cafe-racer-classic-fullface-royal-m18-5_0061169_235.jpg</image>
    <price>1.100.000 ₫</price>
    <producer>ROYAL HELMET</producer>
    <store>FanFan</store>
</product>
<product type="helmet">
    <name>Classic FULLFACE ROYAL M18</name>
    <url>/vi/classic-fullface-royal-m18</url>
    <image>https://fanfan.vn/Uploads/t/fa/fanfan0non-bao-hiem-cafe-racer-classic-fullface-royal-m18-5_0061169_235.jpg</image>
    <price>1.100.000 ₫</price>
    <producer>ROYAL HELMET</producer>
    <store>FanFan</store>
</product>

我尝试了很多方法，但是现在没有希望了。有人知道为什么吗？请帮忙。尽管我是在特定上下文中使用xpath的，但我无法了解xpath的工作原理？

Answer 1

我想问题出在for循环内的fetchFanFanData（）方法中通过访问url，名称等的值。在这里，您必须将“ // ”替换为“ .// ” 用于所有访问，例如替换

 String url = xpath.evaluate("//p[@class=\"name text-uppercase mb-0\"]/a/@href", node, XPathConstants.STRING).toString();

使用

 String url = xpath.evaluate(".//p[@class=\"name text-uppercase mb-0\"]/a/@href", node, XPathConstants.STRING).toString();

“ // ”和“ .// ”之间的区别是：

“ // para ”选择[...]与上下文节点相同的文档中的所有para元素

“ .// para ”选择上下文节点的para元素后代

来自https://www.w3.org/TR/2017/REC-xpath-31-20170321/ 一般而言，尤其是第3.3.5章的“示例”部分。并且 https://docs.oracle.com/javase/10/docs/api/javax/xml/xpath/package-summary.html。

总是获得相同值的原因是：表达式

 "//p[@class=\"name text-uppercase mb-0\"]/a/@href"

应用于列表节点的

还返回一个列表，其中包含整个文档中的所有匹配项（而不是单个匹配项）。此外，该列表对于每个节点都是相同的。与返回类型XPathConstants.STRING结合使用时，始终会选择第一个（相同）匹配项。因此，每个节点都返回相同的结果。

Xpath始终返回JAVA中XML的第一个子节点

1 个答案: