使用 DOM 解析 Java XML 以获取节点值
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Java XML parsing using DOM to get nodevalue
提问by kal
try {
String data = "<a><b c='d' e='f'>0.15</b></a>";
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory
.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory
.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(data));
Document document = documentBuilder.parse(is);
NodeList nl = document.getElementsByTagName("b");
Node n = (Node) nl.item(0);
System.out.println(n.getNodeValue());
} catch (Exception e) {
System.out.println("Exception " + e);
}
I am expecting it to print 0.15, but it prints null. Any Ideas?
我期望它打印 0.15，但它打印 null。有任何想法吗？
Edit: This did the trick
编辑：这成功了
if (n.hasChildNodes())
System.out.println(n.getFirstChild().getNodeValue());
else
System.out.println(n.getNodeValue());
回答by karim79
Try extracting it from the Element rather than from the Node:
尝试从 Element 而不是从 Node 中提取它：
try {
String data = "<a><b c='d' e='f'>0.15</b></a>";
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory
.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory
.newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader(data));
Document document = documentBuilder.parse(is);
NodeList nl = document.getElementsByTagName("b");
Element el = (Element) nl.item(0);
Text elText = (Text) el.getFirstChild();
String theValue = elText.getNodeValue();
System.out.println(theValue);
} catch (Exception e) {
System.out.println("Exception " + e);
}
回答by Sebastian Paaske T?rholm
That's because an element in fact has no nodeValue. Instead it has a text node as a child, which has the nodeValueyou want.
那是因为元素实际上没有nodeValue. 相反，它有一个文本节点作为子节点，其中包含nodeValue您想要的。
In short, you'll want to getNodeValue()on the first child of the element node.
简而言之，您需要getNodeValue()在元素节点的第一个子节点上。
Sometimes the element contains multiple text nodes, as they do have a maximum size, in which case you'll need something á la this, from the page linked earlier:
有时元素包含多个文本节点，因为它们确实有最大大小，在这种情况下，您需要从前面链接的页面中获取一些内容：
public static String getNodeValue(Node node) {
StringBuffer buf = new StringBuffer();
NodeList children = node.getChildNodes();
for (int i = 0; i < children.getLength(); i++) {
Node textChild = children.item(i);
if (textChild.getNodeType() != Node.TEXT_NODE) {
System.err.println("Mixed content! Skipping child element " + textChild.getNodeName());
continue;
}
buf.append(textChild.getNodeValue());
}
return buf.toString();
}
回答by adatapost
System.out.println(n.getFirstChild().getNodeValue());
回答by brian_d
If the node has no further nested descendants, than n.getTextContent()works quite well.
如果节点没有进一步嵌套的后代，则n.getTextContent()效果很好。
回答by iKushal
private String getTextValue(Element element, String string) {
String textVal = null;
NodeList nl = element.getElementsByTagName(string);
if(nl != null && nl.getLength() > 0) {
Element el = (Element)nl.item(0);
textVal = el.getFirstChild().getNodeValue();
}
return textVal;
}
回答by Lukas Eder
You could use jOOXas a wrapper for standard DOM, to simplify your code.
您可以使用jOOX作为标准 DOM 的包装器，以简化您的代码。
String data = "<a><b c='d' e='f'>0.15</b></a>";
String value = $(data).find("b").text();
You could also have jOOX convert that value to double, for instance:
您还可以让 jOOX 将该值转换为双精度值，例如：
Double value = $(data).find("b").text(Double.class);
