java - 无法使用 Element.getAttribute() 获取元素值

Question

我想读取一个 xml 文件。我找到了一个很好的例子，直到 xml 元素没有任何属性。当然，我已经尝试过如何读取属性，但它不起作用。

例如 XML

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<car>
<properties>
<test h="1.12" w="4.2">
<colour>red</colour>
</test>
</properties>
</car>

Java 代码:

public void readXML(String file) {
    try {

        File fXmlFile = new File(file);
        DocumentBuilderFactory dbFactory = DocumentBuilderFactory
                .newInstance();
        DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
        doc = dBuilder.parse(fXmlFile);
        doc.getDocumentElement().normalize();

        for (int temp = 0; temp < nList.getLength(); temp++) {

            Node nNode = nList.item(temp);
            if (nNode.getNodeType() == Node.ELEMENT_NODE) {

                Element eElement = (Element) nNode;

                System.out.println("test : "
                        + getTagValue("test", eElement));
                System.out.println("colour : " + getTagValue("colour", eElement));

            }
        }

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

public String getTagValue(String sTag, Element eElement) {
    NodeList nlList = eElement.getElementsByTagName(sTag).item(0)
            .getChildNodes();


    Node nValue = (Node) nlList.item(0);
            System.out.println(nValue.hasAttributes());

    if (sTag.startsWith("test")) {
        return eElement.getAttribute("w");

    } else {
        return nValue.getNodeValue();
    }

}

输出:

假的

测试:

错误

颜色:红色

我的问题是，我无法打印出属性。我怎样才能得到属性？

Answer 1

你的代码有很多错误；未声明的变量和看似疯狂的算法。我重写了它并且它有效:

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 final class LearninXmlDoc
{
    private static String getTagValue(final Element element)
    {
        System.out.println(element.getTagName() + " has attributes: " + element.hasAttributes());

        if (element.getTagName().startsWith("test"))
        {
            return element.getAttribute("w");

        }
        else
        {
            return element.getNodeValue();
        }
    }

    public static void main(String[] args)
    {
        final String fileName = "c:\\tmp\\test\\domXml.xml";

        readXML(fileName);
    }

    private static void readXML(String fileName)
    {
        Document document;
        DocumentBuilder documentBuilder;
        DocumentBuilderFactory documentBuilderFactory;
        NodeList nodeList;
        File xmlInputFile;

        try
        {
            xmlInputFile = new File(fileName);
            documentBuilderFactory = DocumentBuilderFactory.newInstance();
            documentBuilder = documentBuilderFactory.newDocumentBuilder();
            document = documentBuilder.parse(xmlInputFile);
            nodeList = document.getElementsByTagName("*");

            document.getDocumentElement().normalize();

            for (int index = 0; index < nodeList.getLength(); index++)
            {
                Node node = nodeList.item(index);
                if (node.getNodeType() == Node.ELEMENT_NODE)
                {
                    Element element = (Element) node;

                    System.out.println("\tcolour : " + getTagValue(element));
                    System.out.println("\ttest : " + getTagValue(element));
                    System.out.println("-----");
                }
            }
        }
        catch (Exception exception)
        {
            exception.printStackTrace();
        }
    }
}