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

问题描述

1. 在运行时接受2个参数（一串XML ，和一个xpath查询）


2. 以文本形式返回结果

这可能非常简单但有两个障碍：

1. 这需要在groovy中完成


2. 没有关于groovy或Java的......

这就像我通过将各种代码一起窃取一样，但现在我' m卡住：

  import javax.xml.parsers.DocumentBuilderFactory; 
导入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。我现在怎么得到这个结果（作为一个字符串）？

谢谢

解决方案

  import javax.xml.xpath。* 
 import javax.xml.parsers.DocumentBuilderFactory 
 
 def testxml ='''
< records> 
< car name =HSV Maloomake =Holdenyear =2006> 
< country>澳大利亚< / country> 
< record type =speed>速度为271kph的生产皮卡车< / 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'）
  

看看这个页面（以前是Groovy Docs的一部分），以了解如何遍历XPath查询，这些查询将返回多个结果： b
$ b

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

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

1. Accepts 2 parameters at runtime (a string of XML, and an xpath query)
2. Returns the result as text

This is probably quite straightforward but for two obstacles:

1. This has to be done in groovy
2. I know next to nothing nothing about groovy or Java…

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)

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

Thanks

解决方案

You can do something like this:

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' )

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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