使用DOM解析器解析XML字符串返回null

Question

我正在尝试从XML字符串中获取嵌套的子值，该XML字符串是从DB检索为字符串（无法修改此步骤）。无论我做什么，该属性值都会一直返回为null。我需要fbw和bbw标签的字符串值。

我尝试了getElementsByTagName的每种不同组合。它们都返回null。

String xml = "<?xml version=\"1.0\" encoding = \"UTF-8\" standalone = \"yes\"?><imageresponse><id>123</id><fbw>FWB</fbw><bbw>BBW</bbw></imageresponse>"

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new InputSource(new StringReader(xml)));
NodeList nodeList = doc.getElementsByTagName("imageresponse/fbw");```

这是xml：

<?xml version="1.0" encoding = "UTF-8" standalone = "yes"?>
<imageresponse>
    <id>123</id>
    <fbw>FWB</fbw>
    <bbw>BBW</bbw>
</imageresponse>

Answer 1

我从未亲自看到xpath与getElementsByTagName一起使用，但我见过xpath与xPath类一起使用。

    XPath xPather = XPathFactory.newInstance().newXPath();

    String expression = "/imageresponse/fbw";
    NodeList nodeList = (NodeList) xPather.compile(expression).evaluate(doc, XPathConstants.NODESET);

如果您想同时获得fwb和bbw标签：

String expression = "/imageresponse/fbw | /imageresponse/bbw";