如何在 Groovy 中创建 XPath 函数 [英] How do I create an XPath function in Groovy

问题描述

我正在尝试在 Groovy 中创建一个执行以下操作的函数:

I'm trying to create a function in Groovy that does the following:

1. 在运行时接受 2 个参数(一个 XML 字符串和一个 xpath 查询)
2. 以文本形式返回结果

这可能很简单，但有两个障碍:

This is probably quite straightforward but for two obstacles:

1. 这必须在 groovy 中完成
2. 我对 groovy 或 Java 几乎一无所知......

这是我通过一起破解各种代码获得的，但现在我卡住了:

This is as far as I've got by hacking various bits of code together, but now I'm stuck:

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.*;

builder  = DocumentBuilderFactory.newInstance().newDocumentBuilder();
doc      = builder.parse(new ByteArrayInputStream(xml.bytes));
expr     = XPathFactory.newInstance().newXPath().compile(expression);
Object result = expr.evaluate(doc, XPathConstants.NODESET)

其中xml"和表达式"是运行时参数.我现在如何获得它以返回结果(作为字符串)?

where "xml" and "expression" are runtime parameters. How do I get this now to return the result (as a string)?

谢谢

推荐答案

你可以这样做:

import javax.xml.xpath.*
import javax.xml.parsers.DocumentBuilderFactory

def testxml = '''
    <records>
      <car name="HSV Maloo" make="Holden" year="2006">
        <country>Australia</country>
        <record type="speed">Production Pickup Truck with speed of 271kph</record>
      </car>
    </records>
  '''

def processXml( String xml, String xpathQuery ) {
  def xpath = XPathFactory.newInstance().newXPath()
  def builder     = DocumentBuilderFactory.newInstance().newDocumentBuilder()
  def inputStream = new ByteArrayInputStream( xml.bytes )
  def records     = builder.parse(inputStream).documentElement
  xpath.evaluate( xpathQuery, records )
}

println processXml( testxml, '//car/record/@type' )

查看此页面(以前是 Groovy Docs 的一部分)了解如何循环返回多个结果的 XPath 查询:

Have a look at this page (formerly part of the Groovy Docs) for how to loop over XPath queries that will return multiple results:

http://groovy.jmiguel.eu/groovy.codehaus.org/Reading+XML+with+Groovy+and+XPath.html

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