Xpath Java通过测试值获取元素 [英] Xpath Java get element by testing value
问题描述
我正在尝试使用Xpath来解析一个xml字符串，但我不知道如何使用表达式来检索我想要的。
我有以下xml内容：
< root1>
< root2>
< A>某事< / A>
< B>某事< / B>
< C>
&D
< E> DataE< / E>
< F> DataF< / F>
< G>某事< / G>
< H>某事< / H>
< I>
< J
< K> DataK< / K>
< L> DataL< / L>
< / J>
< / I>
< / D>
&D
< E> DataE_ERROR< / E>
< F> DataF< / F>
< G>某事< / G>
< H>某事< / H>
< I>
< J
< K> DataK< / K>
< L> DataL< / L>
< / J>
< / I>
< / D>
< / C>
< / root2>
< / root1>
我想获取F，K，L的值，当E的值为DataE for
我正在使用这个Xpath，但是找不到好的表情！
here是我的java代码：
public void getit（）
{
String xml =上面的xml ;
DocumentBuilderFactory f = DocumentBuilderFactory.newInstance（）;
DocumentBuilder b = f.newDocumentBuilder（）;
文档d = b.parse（new InputSource（new StringReader（xml）））;
d.getDocumentElement（）。normalize（）;
//不知道！如何通过测试E
的值来使其工作String expression =// E / text（）| // F / text（）| // K / text（）| // L / text（ ）;
XPath xPath = XPathFactory.newInstance（）。newXPath（）;
Object result = xPath.compile（expression）.evaluate（d，XPathConstants.NODESET）;
NodeList nodes =（NodeList）result; （int i = 0; i< nodes.getLength（）; i ++）{
System.out.println（nodes.item（i）.getNodeValue（））;
}
}
只是这样我可以确保查询正常工作，我修改了如下的示例XML ...
< root1> ;
< root2>
< A>某事< / A>
< B>某事< / B>
< C>
&D
< E> DataE< / E>
< F> DataF 1< / F>
< G>某事< / G>
< H>某事< / H>
< I>
< J
< K> DataK 1< / K>
< L> DataL 1< / L>
< / J>
< / I>
< / D>
&D
< E> DataE_ERROR< / E>
< F> DataF 2< / F>
< G>某事< / G>
< H>某事< / H>
< I>
< J
< K> DataK 2< / K>
< L> DataL 2< / L>
< / J>
< / I>
< / D>
< / C>
< / root2>
< / root1>
魔术在这里...
String expression =// F [ancestor :: D / E [text（）='DataE']] | // K [ancestor :: D / E [text（）= 'DataE']] | // L [ancestor :: D / E [tex
基本上这个读取...
查找任何 F 节点，谁有一个祖先包含 D 与 E 的孩子，其文本等于 DataE 或...
现在，这很重要，您可以使用 ../ 来查找父节点，但 K 和 L 被埋在子节点中，我不知道它们是否可能更深或更浅，所以我去了这个方法。
您可能需要对其进行细化，但我将关系 D / E 重要。
有了这个（和下面的例子），我能够生成以下输出...
找到DataF 1
找到DataK 1
找到DataL 1
可运行示例：
public class TestXPath {
public static void main（String [] args）{
String xml =上面的xml;
try {
DocumentBuilderFactory f = DocumentBuilderFactory.newInstance（）;
DocumentBuilder b = f.newDocumentBuilder（）;
文档d = b.parse（new File（Values.xml））;
d.getDocumentElement（）。normalize（）;
String expression =// F [ancestor :: D / E [text（）='DataE']] | // K [ancestor :: D / E [text（）=' ']] | // L [祖先:: D / E [文本（）=' DataE']];
XPath xPath = XPathFactory.newInstance（）。newXPath（）;
Object result = xPath.compile（expression）.evaluate（d，XPathConstants.NODESET）;
NodeList nodes =（NodeList）result; （int i = 0; i< nodes.getLength（）; i ++）{
Node node = nodes.item（i）;
System.out.println（Found+ node.getTextContent（））;
}
} catch（ParserConfigurationException | SAXException | IOException | XPathExpressionException | DOMException exp）{
exp.printStackTrace（）;
}
}
}
I'm trying to use Xpath to parse an xml string, but i don't know how use the expression to retrieve what i want.
I have the following xml content :
<root1>
<root2>
<A>something</A>
<B>something</B>
<C>
<D>
<E>DataE</E>
<F>DataF</F>
<G>something</G>
<H>something</H>
<I>
<J>
<K>DataK</K>
<L>DataL</L>
</J>
</I>
</D>
<D>
<E>DataE_ERROR</E>
<F>DataF</F>
<G>something</G>
<H>something</H>
<I>
<J>
<K>DataK</K>
<L>DataL</L>
</J>
</I>
</D>
</C>
</root2>
</root1>
I would like to get the value of F,K,L when the value of E is DataE for example.
I'm using for this Xpath but i can't find the good expression !
here is my java code :
public void getit()
{
String xml = "The xml above";
DocumentBuilderFactory f = DocumentBuilderFactory.newInstance();
DocumentBuilder b = f.newDocumentBuilder();
Document d = b.parse(new InputSource(new StringReader(xml)));
d.getDocumentElement().normalize();
// No idea ! how can i make it work by testing the value of E
String expression = "//E/text()|//F/text()|//K/text()|//L/text()";
XPath xPath = XPathFactory.newInstance().newXPath();
Object result = xPath.compile(expression).evaluate(d, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getNodeValue());
}
}
Just so I could ensure the query was working, I modified the example XML as follows...
<root1>
<root2>
<A>something</A>
<B>something</B>
<C>
<D>
<E>DataE</E>
<F>DataF 1</F>
<G>something</G>
<H>something</H>
<I>
<J>
<K>DataK 1</K>
<L>DataL 1</L>
</J>
</I>
</D>
<D>
<E>DataE_ERROR</E>
<F>DataF 2</F>
<G>something</G>
<H>something</H>
<I>
<J>
<K>DataK 2</K>
<L>DataL 2</L>
</J>
</I>
</D>
</C>
</root2>
</root1>
The magic is here...
String expression = "//F[ancestor::D/E[text()='DataE']]|//K[ancestor::D/E[text()='DataE']]|//L[ancestor::D/E[tex
Basically, this reads...
Find any F node, who has an ancestor that contains D with a child of E whose text is equal to DataE or ...
Now, this is important, you could use ../ to find the parent node, but K and L are buried in sub nodes and I'm not sure if they might be deeper or shallow, so I went for this method.
You might need to refine it a bit, but I took the relationship of D/E as been important.
With this (and the example below), I was able to generate the following output...
Found DataF 1
Found DataK 1
Found DataL 1
Runnable example:
public class TestXPath {
public static void main(String[] args) {
String xml = "The xml above";
try {
DocumentBuilderFactory f = DocumentBuilderFactory.newInstance();
DocumentBuilder b = f.newDocumentBuilder();
Document d = b.parse(new File("Values.xml"));
d.getDocumentElement().normalize();
String expression = "//F[ancestor::D/E[text()='DataE']]|//K[ancestor::D/E[text()='DataE']]|//L[ancestor::D/E[text()='DataE']]";
XPath xPath = XPathFactory.newInstance().newXPath();
Object result = xPath.compile(expression).evaluate(d, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
Node node = nodes.item(i);
System.out.println("Found " + node.getTextContent());
}
} catch (ParserConfigurationException | SAXException | IOException | XPathExpressionException | DOMException exp) {
exp.printStackTrace();
}
}
}
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