我想使用 java 从这个 XML 树中提取所有 <link> 标签答案

【问题标题】：I want to extract out all the <link> tags from this XML tree using java我想使用 java 从这个 XML 树中提取所有 <link> 标签
【发布时间】：2020-09-03 17:39:25
【问题描述】：

我有一个 XML 文件，它有一个 3 级深度的 XML 树。我想从那棵树中提取所有<link> 标签。这里的挑战是树是动态的并且可以是任何级别的深度。

我已经提取了根节点<helplinks>，我有两种方法可供使用：

-> XmlUtil.getChildNodes(Node node,"name of the child") ~~从父节点返回一个子节点列表。

<helplinks message="Check these links out if you are trying to accomplish something like this: \\n">
        <category name="Connectivity" value = "1" jsonValue="MEP">
            <link name="Reset Password" value="https://www.google.com"></link>
            <link name="Rename User" value="https://www.google.com"></link>
            <link name="Change Database" value="https://www.google.com"></link>
            <subcategory name="Internet" value = "1" jsonValue="MES">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <item name="Not Working" value = "1" jsonValue="MDS">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                </item>
                <item name="Working Slow" value = "2" jsonValue="MLP">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                    <link name="Option 5" value="https://www.google.com"></link>
                </item>
            </subcategory>
            <subcategory name="VPN" value = "2" jsonValue="MES">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <link name="Option 4" value="https://www.google.com"></link>
                <link name="Option 5" value="https://www.google.com"></link>
                <item name="Not Working" value = "1" jsonValue="MDS">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                </item>
                <item name="Working Slow" value = "2" jsonValue="MLP">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
            </subcategory>
        </category>
        <category name="Desktop/Laptop Issue" value = "2" jsonValue="LPM">
            <link name="Option 1" value="https://www.google.com"></link>
            <link name="Option 2" value="https://www.google.com"></link>
            <subcategory name="Machine Down" value = "1" jsonValue="LPN">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <item name="Power Down" value = "1" jsonValue="LMR">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                </item>
                <item name="Blank Screen" value = "2" jsonValue="LMV">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                </item>
            </subcategory>
            <subcategory name="Machine Slow" value = "2" jsonValue="LPO">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <item name="Laptop" value = "1" jsonValue="LMA">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                </item>
                <item name="Desktop" value = "2" jsonValue="LMQ">
                    <link name="Option 1" value="https://www.google.com"></link>
                </item>
            </subcategory>
            <subcategory name="Need Upgrade" value = "3" jsonValue="LPC">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <item name="Laptop" value = "1" jsonValue="LMT">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
                <item name="Desktop" value = "2" jsonValue="LMP">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
            </subcategory>
            <subcategory name="Hardware Problem" value = "4" jsonValue="LPR">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <link name="Option 4" value="https://www.google.com"></link>
                <link name="Option 5" value="https://www.google.com"></link>
                <link name="Option 6" value="https://www.google.com"></link>
                <item name="Screen Problem" value = "1" jsonValue="LMW">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
                <item name="HardDisk Problem" value = "2" jsonValue="LMG">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
                <item name="Keyboard Problem" value = "3" jsonValue="LMH">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
                <item name="Others" value = "4" jsonValue="LMI">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
            </subcategory>
        </category>
        <category name="Business Application Issue" value = "3" jsonValue="ABC">
            <link name="Option 1" value="https://www.google.com"></link>
            <link name="Option 2" value="https://www.google.com"></link>
            <link name="Option 3" value="https://www.google.com"></link>
            <subcategory name="ERP" value = "1" jsonValue="ABC1">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <link name="Option 4" value="https://www.google.com"></link>
                <link name="Option 5" value="https://www.google.com"></link>
                <link name="Option 6" value="https://www.google.com"></link>
                <item name="Login Issue" value = "1" jsonValue="ABC11">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                    <link name="Option 5" value="https://www.google.com"></link>
                    <link name="Option 6" value="https://www.google.com"></link>
                </item>
                <item name="Workflow Issue" value = "2" jsonValue="ABC12">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
            </subcategory>
            <subcategory name="CRM" value = "2" jsonValue="ABC2">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <item name="Login Issue" value = "1" jsonValue="ABC21">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                    <link name="Option 5" value="https://www.google.com"></link>
                    <link name="Option 6" value="https://www.google.com"></link>
                </item>
                <item name="Workflow Issue" value = "2" jsonValue="ABC22">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                    <link name="Option 5" value="https://www.google.com"></link>
                    <link name="Option 6" value="https://www.google.com"></link>
                </item>
            </subcategory>
            <subcategory name="Email" value = "3" jsonValue="ABC3">
                <link name="Option 1" value="https://www.google.com"></link>
                <link name="Option 2" value="https://www.google.com"></link>
                <link name="Option 3" value="https://www.google.com"></link>
                <item name="Send Receive Issue" value = "1" jsonValue="ABC31">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                    <link name="Option 4" value="https://www.google.com"></link>
                    <link name="Option 5" value="https://www.google.com"></link>
                    <link name="Option 6" value="https://www.google.com"></link>
                </item>
                <item name="Archive Issue" value = "2" jsonValue="ABC32">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
                <item name="Space issue" value = "3" jsonValue="ABC33">
                    <link name="Option 1" value="https://www.google.com"></link>
                    <link name="Option 2" value="https://www.google.com"></link>
                    <link name="Option 3" value="https://www.google.com"></link>
                </item>
            </subcategory>
        </category>
    </helplinks>

明确地说，我的目标是提取所有 <link> 标记，而不管嵌套如何。

【问题讨论】：

你有什么问题？
我无法提出一种算法来提取所有链接标签。
请考虑您可以使用的工具，而不是算法。一种方法是使用 xPath (javax.xml.xpath.XPathExpression)。有了这个，您可以通过简单的"//link" 搜索访问每个link 标记，而不管XML 的层次结构如何。然后，您可以为每个节点提取名称和 URL 值 - 甚至获取父类别的文本。做一些研究，找到一个教程。试试看。如果您遇到困难，您可以提出更具体的问题（假设尚未提出），并显示您的具体代码/尝试。
非常感谢@andrewjames，这正是我想要的。

标签： java algorithm

【解决方案1】：

import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;

import java.io.File;
import java.util.Map;

public class Test {
    public static void main(String[] args) throws Exception {
        File file = new File("C:\\Users\\rishabh.awatani\\Downloads\\something.xml");
        DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
        Document document = documentBuilder.parse(file);
        XPath xPath = XPathFactory.newInstance().newXPath();
        String expression = "//link";
        NodeList nodeList = (NodeList) xPath.compile(expression).evaluate(document, XPathConstants.NODESET);
        for(int i = 0; i<nodeList.getLength(); i++){
            Node node = nodeList.item(i);
            NamedNodeMap nodeMap = node.getAttributes();
            System.out.println(nodeMap.getNamedItem("name").getNodeValue() + " ----> " + nodeMap.getNamedItem("value").getNodeValue());
        }
    }
}

这对我有用，因为树结构不是我关心的问题。使用XPath查找所有<link>标签，然后提取出不同元素的值。

【讨论】：