是否有一个针对Ubuntu和/或CentOS的包,它有一个命令行工具,可以执行像foo //element@attribute filename.xml或foo //element@attribute < filename.xml这样的XPath一行程序,并逐行返回结果?

我正在寻找一些东西,这将允许我只是apt-get安装foo或yum安装foo,然后只是开箱即用,没有包装或其他必要的适应。

以下是一些很接近的例子:

Nokogiri。如果我写这个包装器,我可以用上面描述的方式调用包装器:

#!/usr/bin/ruby

require 'nokogiri'

Nokogiri::XML(STDIN).xpath(ARGV[0]).each do |row|
  puts row
end

XML:: XPath。将与此包装工作:

#!/usr/bin/perl

use strict;
use warnings;
use XML::XPath;

my $root = XML::XPath->new(ioref => 'STDIN');
for my $node ($root->find($ARGV[0])->get_nodelist) {
  print($node->getData, "\n");
}

xpath从XML:: xpath返回太多噪音,——NODE——和attribute = "value"。

来自XML::Twig的xml_grep不能处理不返回元素的表达式,因此不能在没有进一步处理的情况下用于提取属性值。

编辑:

Echo cat //element/@attribute | xmllint——shell filename.xml返回类似xpath的噪声。

Xmllint——xpath //element/@attribute filename.xml返回attribute = "value"。

xmllint——xpath 'string(//element/@attribute)' filename.xml返回我想要的,但只对第一个匹配。

对于另一个几乎可以满足这个问题的解决方案,下面是一个可以用于计算任意XPath表达式的XSLT(需要XSLT处理器中的dyn:evaluate支持):

<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"
    xmlns:dyn="http://exslt.org/dynamic" extension-element-prefixes="dyn">
  <xsl:output omit-xml-declaration="yes" indent="no" method="text"/>
  <xsl:template match="/">
    <xsl:for-each select="dyn:evaluate($pattern)">
      <xsl:value-of select="dyn:evaluate($value)"/>
      <xsl:value-of select="'&#10;'"/>
    </xsl:for-each> 
  </xsl:template>
</xsl:stylesheet>

使用xsltproc——stringparam pattern //element/@attribute——stringparam value运行。arbitrary-xpath。xslt filename.xml。


当前回答

A minimal wrapper for python's lxml module that will print all matching nodes by name (at any level), e.g. mysubnode or an XPath subset e.g. //intermediarynode/subnode. If the expression evaluates to text then text will be printed, if it evaluates to an element then the entire raw element will be rendered to text. It also attempts to handle XML namespaces in a way that allows using local tag names without prefixing. With extended XPath mode enabled via the -x flag the default namespace needs to be referenced with the p: prefix, e.g. //p:tagname/p:subtag

#!/usr/bin/env python3
import argparse
import os
import sys

from lxml import etree

DEFAULT_NAMESPACE_KEY = 'p'

def print_element(elem):
    if isinstance(elem, str):
        print(elem)
    elif isinstance(elem, bytes):
        print(elem.decode('utf-8'))
    else:
        print(elem.text and elem.text.strip() or etree.tostring(elem, encoding='unicode', pretty_print=True))


if __name__ == '__main__':

    parser = argparse.ArgumentParser(description='XPATH lxml wrapper',
                                     usage="""
    Print all nodes by name in XML file:                                     
    \t{0} myfile.xml somename

    Print all nodes by XPath selector (findall: reduced subset):                                     
    \t{0} myfile.xml //itermediarynode/childnode

    Print attribute values by XPath selector 'p' maps to default namespace (xpath 1.0: extended subset):                                     
    \t{0} myfile.xml //p:itermediarynode/p:childnode/@src -x
                          
     """.format(os.path.basename(sys.argv[0])))
    parser.add_argument('xpath_file',
                        help='XPath file path')
    parser.add_argument('xpath_expression',
                        help='tag name or xpath expression')
    parser.add_argument('--force_xpath', '-x',
                        action='store_true',
                        default=False,
                        help='Use lxml.xpath (rather than findall)'
    )

    args = parser.parse_args(sys.argv[1:])
    xpath_expression = args.xpath_expression

    tree = etree.parse(args.xpath_file)

    ns = tree.getroot().nsmap

    if args.force_xpath:
        if ns.keys() and None in ns:
            ns[DEFAULT_NAMESPACE_KEY] = ns.pop(None)
        for node in tree.xpath(xpath_expression, namespaces=ns):
            print_element(node)

    elif xpath_expression.isalpha():
        for node in tree.xpath(f"//*[local-name() = '{xpath_expression}']"):
            print_element(node)
    else:
        for el in tree.findall(xpath_expression, namespaces=ns):
            print_element(el)


它使用lxml -一个用C编写的快速XML解析器,它不包含在标准python库中。使用pip Install lxml安装它。在Linux/OSX上可能需要用sudo作为前缀。

用法:

python3 xmlcat.py file.xml "//mynode"

lxml也可以接受URL作为输入:

python3 xmlcat.py http://example.com/file.xml "//mynode" 

提取框节点下的url属性,即<enclosure url="http:…""..>)(-x强制扩展XPath 1.0子集):

python3 xmlcat.py xmlcat.py file.xml "//enclosure/@url" -x

在谷歌Chrome中的Xpath

作为一个无关的边注:如果碰巧你想运行一个XPath表达式对网页的标记,那么你可以直接从Chrome devtools:右键单击页面在Chrome >选择检查,然后在devtools控制台粘贴你的XPath表达式为$x("//spam/eggs")。

获取本页上的所有作者:

$x("//*[@class='user-details']/a/text()")

其他回答

clacke的回答很好,但我认为只有当你的源代码是格式良好的XML,而不是普通的HTML时才有效。

因此,对于正常的Web内容- html文档(不一定是格式良好的XML),也要做同样的事情:

echo "<p>foo<div>bar</div><p>baz" | python -c "from sys import stdin; \
from lxml import html; \
print '\n'.join(html.tostring(node) for node in html.parse(stdin).xpath('//p'))"

而使用html5lib(以确保您获得与Web浏览器相同的解析行为——因为像浏览器解析器一样,html5lib符合HTML规范中的解析要求)。

echo "<p>foo<div>bar</div><p>baz" | python -c "from sys import stdin; \
import html5lib; from lxml import html; \
doc = html5lib.parse(stdin, treebuilder='lxml', namespaceHTMLElements=False); \
print '\n'.join(html.tostring(node) for node in doc.xpath('//p'))

你应该试试这些工具:

xmlstarlet (xmlstarlet page) : can edit, select, transform... Not installed by default, xpath1 xmllint (man xmllint): often installed by default with libxml2-utils, xpath1 (check my wrapper to have --xpath switch on very old releases and newlines delimited output (v < 2.9.9)). Can be used as interactive shell with the --shell switch. xpath : installed via perl's module XML::Xpath, xpath1 xml_grep : installed via perl's module XML::Twig, xpath1 (limited xpath usage) xidel (xidel): xpath3 saxon-lint (saxon-lint): my own project, wrapper over @Michael Kay's Saxon-HE Java library, xpath3: using SaxonHE 9.6 ,XPath 3.x (+retro compatibility)

例子:

xmllint --xpath '//element/@attribute' file.xml
xmlstarlet sel -t -v "//element/@attribute" file.xml
xpath -q -e '//element/@attribute' file.xml
xidel -se '//element/@attribute' file.xml
saxon-lint --xpath '//element/@attribute' file.xml

一个解决方案,即使存在命名空间声明的顶部:

如果xml在顶部声明了名称空间,答案中提出的大多数命令都不能开箱即用。考虑一下:

输入xml:

<elem1 xmlns="urn:x" xmlns:prefix="urn:y">
    <elem2 attr1="false" attr2="value2">
        elem2 value
    </elem2>
    <elem2 attr1="true" attr2="value2.1">
        elem2.1 value
    </elem2>    
    <prefix:elem3>
        elem3 value
    </prefix:elem3>        
</elem1>

不工作:

xmlstarlet sel -t -v "/elem1" input.xml
# nothing printed
xmllint -xpath "/elem1" input.xml
# XPath set is empty

解决方案:

# Requires >=java11 to run like below (but the code requires >=java17 for case syntax to be recognized)

# Prints the whole document
java ExtractXpath.java "/" example-inputs/input.xml

# Prints the contents and self of "elem1"
java ExtractXpath.java "/elem1" input.xml

# Prints the contents and self of "elem2" whose attr2 value is: 'value2'
java ExtractXpath.java "//elem2[@attr2='value2']" input.xml

# Prints the value of the attribute 'attr2': "value2", "value2.1"
java ExtractXpath.java "/elem1/elem2/@attr2" input.xml

# Prints the text inside elem3: "elem3 value"
java ExtractXpath.java "/elem1/elem3/text()" input.xml

# Prints the name of the matched element: "prefix:elem3"
java ExtractXpath.java "name(/elem1/elem3)" input.xml
# Same as above: "prefix:elem3"
java ExtractXpath.java "name(*/elem3)" input.xml

# Prints the count of the matched elements: 2.0
java ExtractXpath.java "count(/elem2)" input.xml


# known issue: while "//elem2" works. "//elem3" does not (it works only with: '*/elem3' )


ExtractXpath.java:


import java.io.File;
import java.io.FileInputStream;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Collectors;

import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathEvaluationResult;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class ExtractXpath {

    public static void main(String[] args) throws Exception {
        assertThat(args.length==2, "Wrong number of args");
        String xpath = args[0];
        File file = new File(args[1]);
             
        assertThat(file.isFile(), file.getAbsolutePath()+" is not a file.");
        FileInputStream fileIS = new FileInputStream(file);
        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = builderFactory.newDocumentBuilder();
        Document xmlDocument = builder.parse(fileIS);
        XPath xPath = XPathFactory.newInstance().newXPath();
        String expression = xpath;
        XPathExpression xpathExpression =  xPath.compile(expression);
        
        XPathEvaluationResult xpathEvalResult =  xpathExpression.evaluateExpression(xmlDocument);
        System.out.println(applyXpathExpression(xmlDocument, xpathExpression, xpathEvalResult.type().name()));
    }

    private static String applyXpathExpression(Document xmlDocument, XPathExpression expr, String xpathTypeName) throws TransformerConfigurationException, TransformerException, XPathExpressionException {

        // see: https://www.w3.org/TR/1999/REC-xpath-19991116/#corelib
        List<String> retVal = new ArrayList();
        if(xpathTypeName.equals(XPathConstants.NODESET.getLocalPart())){ //e.g. xpath: /elem1/*
            NodeList nodeList = (NodeList)expr.evaluate(xmlDocument, XPathConstants.NODESET);
            for (int i = 0; i < nodeList.getLength(); i++) {
                retVal.add(convertNodeToString(nodeList.item(i)));
            }
        }else if(xpathTypeName.equals(XPathConstants.STRING.getLocalPart())){ //e.g. xpath: name(/elem1/*)
            retVal.add((String)expr.evaluate(xmlDocument, XPathConstants.STRING));
        }else if(xpathTypeName.equals(XPathConstants.NUMBER.getLocalPart())){ //e.g. xpath: count(/elem1/*)
            retVal.add(((Number)expr.evaluate(xmlDocument, XPathConstants.NUMBER)).toString());
        }else if(xpathTypeName.equals(XPathConstants.BOOLEAN.getLocalPart())){ //e.g. xpath: contains(elem1, 'sth')
            retVal.add(((Boolean)expr.evaluate(xmlDocument, XPathConstants.BOOLEAN)).toString());
        }else if(xpathTypeName.equals(XPathConstants.NODE.getLocalPart())){ //e.g. xpath: fixme: find one
            System.err.println("WARNING found xpathTypeName=NODE");
            retVal.add(convertNodeToString((Node)expr.evaluate(xmlDocument, XPathConstants.NODE)));
        }else{
            throw new RuntimeException("Unexpected xpath type name: "+xpathTypeName+". This should normally not happen");
        }
        return retVal.stream().map(str->"==MATCH_START==\n"+str+"\n==MATCH_END==").collect(Collectors.joining ("\n"));
        
    }
    
    private static String convertNodeToString(Node node) throws TransformerConfigurationException, TransformerException {
            short nType = node.getNodeType();
        switch (nType) {
            case Node.ATTRIBUTE_NODE , Node.TEXT_NODE -> {
                return node.getNodeValue();
            }
            case Node.ELEMENT_NODE, Node.DOCUMENT_NODE -> {
                StringWriter writer = new StringWriter();
                Transformer trans = TransformerFactory.newInstance().newTransformer();
                trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                trans.setOutputProperty(OutputKeys.INDENT, "yes");
                trans.transform(new DOMSource(node), new StreamResult(writer));
                return writer.toString();
            }
            default -> {
                System.err.println("WARNING: FIXME: Node type:"+nType+" could possibly be handled in a better way.");
                return node.getNodeValue();
            }
                
        }
    }

    
    private static void assertThat(boolean b, String msg) {
        if(!b){
            System.err.println(msg+"\n\nUSAGE: program xpath xmlFile");
            System.exit(-1);
        }
    }
}

@SuppressWarnings("unchecked")
class NamespaceResolver implements NamespaceContext {
    //Store the source document to search the namespaces
    private final Document sourceDocument;
    public NamespaceResolver(Document document) {
        sourceDocument = document;
    }

    //The lookup for the namespace uris is delegated to the stored document.
    @Override
    public String getNamespaceURI(String prefix) {
        if (prefix.equals(XMLConstants.DEFAULT_NS_PREFIX)) {
            return sourceDocument.lookupNamespaceURI(null);
        } else {
            return sourceDocument.lookupNamespaceURI(prefix);
        }
    }

    @Override
    public String getPrefix(String namespaceURI) {
        return sourceDocument.lookupPrefix(namespaceURI);
    }

    @SuppressWarnings("rawtypes")
    @Override
    public Iterator getPrefixes(String namespaceURI) {
        return null;
    }
}

为了简单起见:

xpath-extract命令:

#!/bin/bash
java ExtractXpath.java "$1" "$2"

类似于Mike和clacke的回答,下面是python一行程序(使用python >= 2.5)从pom.xml文件中获取构建版本,该程序绕过了pom.xml文件通常没有dtd或默认名称空间的事实,因此对libxml来说格式不正确:

python -c "import xml.etree.ElementTree as ET; \
  print(ET.parse(open('pom.xml')).getroot().find('\
  {http://maven.apache.org/POM/4.0.0}version').text)"

在Mac和Linux上测试,并且不需要安装任何额外的包。

安装BaseX数据库,然后像这样使用它的“独立命令行模式”:

basex -i - //element@attribute < 文件名.xml

or

{pos(24)}金马资

查询语言实际上是XQuery(3.0),而不是XPath,但由于XQuery是XPath的超集,因此可以毫不注意地使用XPath查询。