如何使用python删除xml中的特定标签

Question

我必须删除 apache-tomcat web.xml 文件中的一些特定标签

web.xml

    <?xml version="1.0" encoding="ISO-8859-1"?>



<web-app xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
  version="3.0">

  <!-- ======================== Introduction ============================== -->
  <!-- This document defines default values for *all* web applications      -->
  <!-- loaded into this instance of Tomcat.  As each application is         -->
  <!-- deployed, this file is processed, followed by the                    -->
  <!-- "/WEB-INF/web.xml" deployment descriptor from your own               -->
  <!-- applications.                                                        -->
  <!--                                                                      -->
  <!-- WARNING:  Do not configure application-specific resources here!      -->
  <!-- They should go in the "/WEB-INF/web.xml" file in your application.   -->

     <servlet>
        <servlet-name>default</servlet-name>
        <servlet-class>org.apache.catalina.servlets.DefaultServlet</servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>0</param-value>
        </init-param>
        <init-param>
            <param-name>listings</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
   <servlet>
        <servlet-name>jsp</servlet-name>
        <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
        <init-param>
            <param-name>fork</param-name>
            <param-value>false</param-value>
        </init-param>
        <init-param>
            <param-name>xpoweredBy</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>3</load-on-startup>
    </servlet>

    <servlet>
        <servlet-name>cgi</servlet-name>
        <servlet-class>org.apache.catalina.servlets.CGIServlet</servlet-class>
        <init-param>
          <param-name>debug</param-name>
          <param-value>0</param-value>
        </init-param>
        <init-param>
          <param-name>cgiPathPrefix</param-name>
          <param-value>WEB-INF/cgi</param-value>
        </init-param>
         <load-on-startup>5</load-on-startup>
    </servlet>
</<web-app>

如果 servlet-name== cgi 我需要删除整个 servlet 标记。 我的代码如下：

    from xml.etree.ElementTree import ElementTree
    tree = ElementTree()
    tree.parse('web.xml')
    servlets = tree.findall('servlet')
    print "servlets : ",servlets
    for servlet in servlets:
      servlet_names = foo.findall('servlet-name')
      for servlet_name  in servlet_names:
            if servlet_name == "cgi" :
                    print "servlet_name :", servlet_name
                    servlet.remove(servlet-name)

我得到 o/p 作为 servlet ：[] 而不是所有的 servlet 并且无法进入 for 循环。 谁能帮帮我？。

我没有得到任何异常

#!/usr/bin/python
from xml.etree.ElementTree import ElementTree
tree = ElementTree()
tree.parse('web.xml')
root = tree.getroot()
ns = '{http://java.sun.com/xml/ns/javaee}'
servlets = root.findall(ns + 'servlet')
print "servlets : ",servlets
for servlet in servlets:
  servlet_names = servlet.findall(ns + 'servlet-name')
  for servlet_name  in servlet_names:
        if servlet_name.text == "cgi" :
                print "servlet_name :", servlet_name.text
                print "removed the cgi serverlet", root.remove(servlet)

=====输出================ servlet : [http://java.sun.com/xml/ns/javaee}servlet at 7f84e09b35a8>, http://java.sun.com/xml/ns/javaee}servlet at 7f84e09b3878>, http://java .sun.com/xml/ns/javaee}servlet 在 7f84e09b3bd8>] servlet_name：cgi 删除了 cgi serverlet 无

==== 我已经使用 pdb 跟踪器来找出元素（servlet）的值，它显示为 \n..

> /apps/manu/python/manunamespace.py(10)<module>()
-> servlet_name=servlet.find('{http://java.sun.com/xml/ns/javaee}servlet-name')
(Pdb) servlet_name
<Element {http://java.sun.com/xml/ns/javaee}servlet-name at 882878>
(Pdb) servlet_name.text
'jsp'
(Pdb) n
> /apps/manu/python/manunamespace.py(11)<module>()
-> print "servlet_name:", servlet_name.text
(Pdb) servlet_name.text
'cgi'
(Pdb) servlet.text
'\n        '
(Pdb) n
servlet_name: cgi
> /apps/manu/python/manunamespace.py(12)<module>()
-> if servlet_name.text == "cgi":
(Pdb) n
> /apps/manu/python/manunamespace.py(13)<module>()
-> print "remove the element"
(Pdb) n
remove the element
> /apps/manu/python/manunamespace.py(14)<module>()
-> print "remove : ",root.remove(servlet)
(Pdb) servlet
<Element {http://java.sun.com/xml/ns/javaee}servlet at 882d88>
(Pdb) servlet.text
'\n 

   '

Answer 1

这失败了：

servlets = tree.findall('servlet')

因为您的文档中没有 servlet 元素。根元素指定：

xmlns="http://java.sun.com/xml/ns/javaee"

这意味着所有元素，除非另有说明，都在这个 XML 命名空间中。所以你想要：

>>> tree.findall('{http://java.sun.com/xml/ns/javaee}servlet')
[<Element {http://java.sun.com/xml/ns/javaee}servlet at 0x7f280ec681b8>,
<Element {http://java.sun.com/xml/ns/javaee}servlet at 0x7f280ec68200>, 
<Element {http://java.sun.com/xml/ns/javaee}servlet at 0x7f280ec682d8>]
>>> 

Answer 2

您没有找到要搜索的标签，因为它们位于默认命名空间 (http://java.sun.com/xml/ns/javaee) 中。

另外，如果你想测试一个元素的内容，你需要使用它的text 属性，而不是与元素本身进行比较。如果匹配，则需要从根目录中删除 servlet-tag，而不是 servlet 中的 servlet-name 标记。

试试这个：

from xml.etree.ElementTree import ElementTree
tree = ElementTree()
tree.parse('web.xml')
root = tree.getroot()
nsmap = {'jee': 'http://java.sun.com/xml/ns/javaee'}
servlets = root.findall('jee:servlet', nsmap)
print "servlets : ",servlets
for servlet in servlets:
  servlet_names = servlet.findall('jee:servlet-name', nsmap)
  for servlet_name  in servlet_names:
        if servlet_name.text == "cgi" :
                print "servlet_name :", servlet_name.text
                root.remove(servlet)

或者更有效地使用supported xpath syntax：

from xml.etree.ElementTree import ElementTree
tree = ElementTree()
tree.parse('web.xml')
root = tree.getroot()
nsmap = {'jee': 'http://java.sun.com/xml/ns/javaee'}
for servlet in root.findall("./jee:servlet[jee:servlet-name='cgi']", nsmap):
    root.remove(servlet)

编辑：对于较旧的python版本（用python2.5测试）：

from xml.etree.ElementTree import ElementTree
tree = ElementTree()
tree.parse('web.xml')
root = tree.getroot()
ns = '{http://java.sun.com/xml/ns/javaee}'
servlets = root.findall(ns + 'servlet')
print "servlets : ",servlets
for servlet in servlets:
  servlet_names = servlet.findall(ns + 'servlet-name')
  for servlet_name  in servlet_names:
        if servlet_name.text == "cgi" :
                print "servlet_name :", servlet_name.text
                root.remove(servlet)