java 使用 XPath 获取 XML 子元素
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Getting XML child elements with XPath
提问by Michael A
I have this XML:
我有这个 XML：
<root>
<items>
<item1>
<tag1>1</tag1>
<sub>
<sub1>10 </sub1>
<sub2>20 </sub2>
</sub>
</item1>
<item2>
<tag1>1</tag1>
<sub>
<sub1> </sub1>
<sub2> </sub2>
</sub>
</item2>
</items>
</root>
I want to get the item1element and the name and values of the child elements.
我想获取item1元素以及子元素的名称和值。
That is, i want to get: tag1- 1,sub1-10,sub2-20.
也就是说，我想得到：tag1- 1 ,sub1 -10 ,sub2 -20。
How can i do this? so far i can only get elements without children.
我怎样才能做到这一点？到目前为止，我只能获得没有孩子的元素。
回答by Avihai Marchiano
Document doc = ...;
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xpath.compile("/root/items/item1/*/text()");
Object o = expr.evaluate(doc, XPathConstants.NODESET);
NodeList list = (NodeList) o;
回答by Franco Rondini
import org.w3c.dom.*;
import javax.xml.parsers.*;
import javax.xml.xpath.*;
/**
* File: Ex1.java @author ronda
*/
public class Ex1 {
public static void main(String[] args) throws Exception {
DocumentBuilderFactory Factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = Factory.newDocumentBuilder();
Document doc = builder.parse("myxml.xml");
//creating an XPathFactory:
XPathFactory factory = XPathFactory.newInstance();
//using this factory to create an XPath object:
XPath xpath = factory.newXPath();
// XPath Query for showing all nodes value
XPathExpression expr = xpath.compile("//" + "item1" + "/*");
Object result = expr.evaluate(doc, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
System.out.println(nodes.getLength());
for (int i = 0; i < nodes.getLength(); i++) {
Element el = (Element) nodes.item(i);
System.out.println("tag: " + el.getNodeName());
// seach for the Text children
if (el.getFirstChild().getNodeType() == Node.TEXT_NODE)
System.out.println("inner value:" + el.getFirstChild().getNodeValue());
NodeList children = el.getChildNodes();
for (int k = 0; k < children.getLength(); k++) {
Node child = children.item(k);
if (child.getNodeType() != Node.TEXT_NODE) {
System.out.println("child tag: " + child.getNodeName());
if (child.getFirstChild().getNodeType() == Node.TEXT_NODE)
System.out.println("inner child value:" + child.getFirstChild().getNodeValue());;
}
}
}
}
}
I get this output loading the xml of your question in file named: myxml.xml:
我得到这个输出，在名为 myxml.xml 的文件中加载你的问题的 xml：
run:
2
tag: tag1
inner value:1
tag: sub
inner value:
child tag: sub1
inner child value:10
child tag: sub2
inner child value:20
...a bit wordy, but allow us to understand how it works. PS: I found a good guide in here
...有点罗嗦，但让我们了解它是如何工作的。PS：我在这里找到了一个很好的指南
