Python 关于xpath查找XML元素的一点总结

关于xpath查找XML元素的一点总结

by:授客 QQ:1033553122

 

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测试环境

Win7 64

 

python 3.4.0

实践出真知

代码如下,更换不同的xpath,和response_to_check进行测试

 

实验1

xpath = ".//xmlns:return//xmlns:copeWith"



response_to_check = '' \

'<soap:Envelope xmlns="http://www.examp.com"  xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" >' \
'    <node2>' \
'        <id>goods1</id>' \
'    </node2>    ' \
'    <ns1:Body xmlns:ns1="http://service.rpt.data.platform.ddt.sf.com/">' \
'        <ns2:selectByPrimaryKeyResponse  xmlns:ns2="http://service.rpt.data.platform.ddt.sf2.com/"  ' \
'                xmlns="http://www.overide_first_defaul_xmlns.com">  ' \
'            <return>' \
'                <copeWith>1.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>144</id>' \
'                <invoice>2</invoice>' \
'                <invoiceType></invoiceType>' \
'                <orderCode>DDT201704071952057186</orderCode>' \
'                <orderDate>2017-04-07 19:52:06.0</orderDate>' \
'                <paid>0.01</paid>' \
'                <payType>pc</payType>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId>2</userId>' \
'            </return>' \
'            <return>' \
'                <copeWith>2.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>143</id>' \
'                <invoice>2</invoice>' \
'                <invoiceType></invoiceType>' \
'                <orderCode>DDT201704071951065731</orderCode>' \
'                <orderDate>2017-04-07 19:51:07.0</orderDate> ' \
'                <paid>0.01</paid>' \
'                <payType>pc</payType>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId>2</userId>' \
'            </return>' \
'            <return>' \
'                <copeWith>3.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>142</id>' \
'                <invoice>2</invoice>' \
'                <invoiceType></invoiceType>' \
'                <orderCode>DDT201704071945408575</orderCode>' \
'                <orderDate>2017-04-07 19:45:40.0</orderDate>' \
'                <paid>0.01</paid>' \
'                <payType>pc</payType>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId>2</userId>' \
'            </return>            ' \
'            <return attr="re">' \
'                 <copeWith>4.00</copeWith>' \
'                <copeWith>5.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>141</id>' \
'                <invoice>1</invoice>' \
'                <invoiceType>增值税普通发票</invoiceType>' \
'                <orderCode>DDT201704071845403738</orderCode>' \
'                <orderDate>2017-04-07 18:45:41.0</orderDate>' \
'                <paid>0.01</paid>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId attr="testattr">2</userId>' \
'            </return>' \
'        </ns2:selectByPrimaryKeyResponse>' \
'    </ns1:Body>' \
'    <ns1:Body xmlns:ns1="http://service.rpt.data.platform.ddt.sf.com/">' \
'        <ns2:selectByPrimaryKeyResponse  xmlns:ns2="http://service.rpt.data.platform.ddt.sf2.com/"> ' \
'        </ns2:selectByPrimaryKeyResponse>' \
'        <ns2:selectByPrimaryKeyResponse  xmlns:ns2="http://service.rpt.data.platform.ddt.sf2.com/"> ' \
'        </ns2:selectByPrimaryKeyResponse>' \
'    </ns1:Body>' \
'</soap:Envelope>'

 

 


root = ET.fromstring(response_to_check)
print(root)

if xpath == '.':
    text_of_element = root.text
else:
    xmlnsnamespace_dic = {}  # 存放名称空间定义
    print('正在获取xmlns定义')

    match_result_list =re.findall('xmlns[^:]?=(.+?)[ |\>|\\\>]', response_to_check, re.MULTILINE)
    if match_result_list:
        xmlns = match_result_list[len(match_result_list) - 1]
        xmlns = xmlns.strip(' ')
        xmlns = '{' + xmlns + '}'
        print('xmlns定义为:%s' % xmlns)

        xmlnsnamespace_dic['xmlns'] = xmlns

    print('正在获取"xmlns:xxx名称空间定义')
    match_result_list = re.findall('xmlns:(.+?)=(.+?)[ |>]', response_to_check)
    for ns in match_result_list:
        xmlnsnamespace_dic[ns[0]] = '{' + ns[1] + '}'

    print("最后获取的prefix:uri为:%s" % xmlnsnamespace_dic)


    print('正在转换元素结点前缀')

    for dic_key in xmlnsnamespace_dic.keys():
        namespace = dic_key + ':'
        if namespace in xpath:

            uri = xmlnsnamespace_dic[dic_key]
            xpath = xpath.replace(namespace, uri)
            xpath = xpath.replace('"','')

    print('转换后用于查找元素的xpath:%s' % xpath)
    try:
        elements_list = root.findall(xpath)
    except Exception as e:
        print('查找元素出错:%s' % e)

    print('查找到的元素为:%s' % elements_list)

    for element in elements_list:
        text_of_element = element.text
        print(text_of_element)

 

 

实验结果

以下为xpath设置不同值时的查找结果

/node
查找结果:报错,不能使用绝对路径

./node2
查找结果:找不到元素

./Body
查找结果:找不到元素

./ns1:Body/selectByPrimaryKeyResponse
查找结果:找不到元素

./ns1:Body/ns2:selectByPrimaryKeyResponse/return

查找结果:找不到元素


./ns1:Body/ns2:selectByPrimaryKeyResponse/xmlns:return[1]/copeWith
查找结果:找不到元素

-----------------------------
.

查找结果:根元素,即Envelope元素

ns1:Body
查找结果:所有名称空间为ns1的Body元素

./ns1:Body
查找结果:等同ns1:Body

./ns1:Body/ns2:selectByPrimaryKeyResponse

查找结果:所有名称空间为ns1的Body元素下的所有名为selectByPrimaryKeyResponse的子元素

./ns1:Body/ns2:selectByPrimaryKeyResponse[2]
查找结果:所有名称空间为ns1的Body元素下,名称空间为ns2的第2个名为selectByPrimaryKeyResponse的子元素

./ns1:Body/ns2:selectByPrimaryKeyResponse/xmlns:return
查找结果:所有名称空间为ns1的Body元素下,所有名称空间为ns2,名称为selectByPrimaryKeyResponse的子元素下,所有名称空间定义为 http://www.overide_first_defaul_xmlns.com的return元素

./ns1:Body/ns2:selectByPrimaryKeyResponse/xmlns:return[1]/xmlns:copeWith

查找结果:所有名称空间为ns1的Body元素下,所有名称空间为ns2,名称为selectByPrimaryKeyResponse的子元素下,第一个名称空间定义为http://www.overide_first_defaul_xmlns.com的return元素下,

名称空间定义为http://www.overide_first_defaul_xmlns.com的copyWith元素

.//xmlns:copeWith
查找结果:所有名称空间定义为http://www.overide_first_defaul_xmlns.com的copeWith元素

.//xmlns:copeWith[2]
查找结果:同一个元素节点下,名称空间定义为http://www.overide_first_defaul_xmlns.com的第二个copeWith元素(例中为 <copeWith>5.00</copeWith>' ,注意:这里的数字是针对兄弟节点的,下同,不再赘述)

# 注意:[]里面不支持last()这种谓词,数字可以

 

.//xmlns:return//xmlns:copeWith"
查找结果:所有名称空间定义为http://www.overide_first_defaul_xmlns.com的return元素下,所有名称空间定义为http://www.overide_first_defaul_xmlns.com的copeWith元素

 

 

实验2

 

对比实验1,去掉selectByPrimaryKeyResponse元素中的xmlns定义:

xmlns="http://www.overide_first_defaul_xmlns.com"


xpath = ".//xmlns:return//xmlns:copeWith"


response_to_check = '' \

'<soap:Envelope xmlns="http://www.examp.com"  xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" >' \
'    <node2>' \
'        <id>goods1</id>' \
'    </node2>    ' \
'    <ns1:Body xmlns:ns1="http://service.rpt.data.platform.ddt.sf.com/">' \
'        <ns2:selectByPrimaryKeyResponse  xmlns:ns2="http://service.rpt.data.platform.ddt.sf2.com/"  ' \
'                >  ' \
'            <return>' \
'                <copeWith>1.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>144</id>' \
'                <invoice>2</invoice>' \
'                <invoiceType></invoiceType>' \
'                <orderCode>DDT201704071952057186</orderCode>' \
'                <orderDate>2017-04-07 19:52:06.0</orderDate>' \
'                <paid>0.01</paid>' \
'                <payType>pc</payType>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId>2</userId>' \
'            </return>' \
'            <return>' \
'                <copeWith>2.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>143</id>' \
'                <invoice>2</invoice>' \
'                <invoiceType></invoiceType>' \
'                <orderCode>DDT201704071951065731</orderCode>' \
'                <orderDate>2017-04-07 19:51:07.0</orderDate> ' \
'                <paid>0.01</paid>' \
'                <payType>pc</payType>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId>2</userId>' \
'            </return>' \
'            <return>' \
'                <copeWith>3.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>142</id>' \
'                <invoice>2</invoice>' \
'                <invoiceType></invoiceType>' \
'                <orderCode>DDT201704071945408575</orderCode>' \
'                <orderDate>2017-04-07 19:45:40.0</orderDate>' \
'                <paid>0.01</paid>' \
'                <payType>pc</payType>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId>2</userId>' \
'            </return>            ' \
'            <return attr="re">' \
'                 <copeWith>4.00</copeWith>' \
'                <copeWith>5.00</copeWith>' \
'                <discount>0.99</discount>' \
'                <id>141</id>' \
'                <invoice>1</invoice>' \
'                <invoiceType>增值税普通发票</invoiceType>' \
'                <orderCode>DDT201704071845403738</orderCode>' \
'                <orderDate>2017-04-07 18:45:41.0</orderDate>' \
'                <paid>0.01</paid>' \
'                <productName>快递包</productName>' \
'                <state>0</state>' \
'                <userId attr="testattr">2</userId>' \
'            </return>' \
'        </ns2:selectByPrimaryKeyResponse>' \
'    </ns1:Body>' \
'    <ns1:Body xmlns:ns1="http://service.rpt.data.platform.ddt.sf.com/">' \
'        <ns2:selectByPrimaryKeyResponse  xmlns:ns2="http://service.rpt.data.platform.ddt.sf2.com/"> ' \
'        </ns2:selectByPrimaryKeyResponse>' \
'        <ns2:selectByPrimaryKeyResponse  xmlns:ns2="http://service.rpt.data.platform.ddt.sf2.com/"> ' \
'        </ns2:selectByPrimaryKeyResponse>' \
'    </ns1:Body>' \
'</soap:Envelope>'

 

实验结果

.//xmlns:return//xmlns:copeWith
查找结果:所有名称空间定义为http://www.examp.com的return元素下,所有名称空间定义为http://www.examp.com的copeWith元素

 

实验3

 

xpath = "./xmlns:string"

response_to_check =''\

    '<ArrayOfString xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"' \
    '   xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://WebXml.com.cn/">' \
    '   <string>阿尔及利亚,3320</string>' \
    '   <string>阿根廷,3522</string>' \
    '   <string>阿曼,3170</string>' \
    '   <string>阿塞拜疆,3176</string>' \
    '   <string>埃及,3317</string>' \
    '   <string>埃塞俄比亚,3314</string>' \
    '   <string>爱尔兰,3246</string>' \
    '   <string>奥地利,3237</string>' \
    '   <string>澳大利亚,368</string>' \
    '   <string>巴基斯坦,3169</string>' \
    '   <string>巴西,3580</string>' \
    '   <string>保加利亚,3232</string>' \
    '   <string>比利时,3243</string>' \
    '</ArrayOfString>'

实验结果:
./string

查找结果:找不到元素

./xmlns:string
查找结果:根元素下,所有名称空间定义为 xmlns的string元素

实验4

对比实验3去掉xmlns=xmlns="http://WebXml.com.cn/

 

 

xpath = "./string"

response_to_check =''\

    '<ArrayOfString xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"' \
    '   xmlns:xsd="http://www.w3.org/2001/XMLSchema">' \
    '   <string>阿尔及利亚,3320</string>' \
    '   <string>阿根廷,3522</string>' \
    '   <string>阿曼,3170</string>' \
    '   <string>阿塞拜疆,3176</string>' \
    '   <string>埃及,3317</string>' \
    '   <string>埃塞俄比亚,3314</string>' \
    '   <string>爱尔兰,3246</string>' \
    '   <string>奥地利,3237</string>' \
    '   <string>澳大利亚,368</string>' \
    '   <string>巴基斯坦,3169</string>' \
    '   <string>巴西,3580</string>' \
    '   <string>保加利亚,3232</string>' \
    '   <string>比利时,3243</string>' \
    '</ArrayOfString>'

 

实验结果:
./string

查找结果:根元素下,所有名称空间定义为 http://WebXml.com.cn/的string元素

总结

1)xmlns=URI定义元素默认的名称空间,使得作用范围内,可不用为元素显示设置名称空间前缀。

<element_node xmlns=URI>

<node1>

    ...

<node2>

</element_node>

 

xmlns=URI的作用域如下:

<element_node xmlns=URI>

    作用域,也就是说,仅在元素范围内

</element>

 

2) 一份xml文档中,同时只能存在一个默认的xmlns名称空间,后续元素标签中定义的xmlns会自动导致前面定义的xmlns不可用

 

3)为元素设置自定义名称空间,形式如下:

<namespace:element_name xmlns:namespace=URI>

</namespace:element_name>

 

4)xpath查找,不能使用绝对路径。

 

5)根据实验1,实验1&实验2对比,实验3&实验4对比得出:

如果设置了xmlns(默认名称空间xmlns=xxxx,或者非默认的自定义名称空间xmlns:prefix=URI),那么xpath查找名称空间作用域内的子元素时,必须使用名称空间查找./xmlns:node_name、./prefix:node_name。

 

如果xmlns默认名称空间作用域范围内,子元素标签内设置了自定义名称空间,那么使用自定义名称空间查找 ./…/prefix:node_name

 

如果既没定义默认名称空间,也没设置自定义名称空间,那么xpath查找元素时可不用指定名称空间 ./node_name

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posted @ 2018-02-07 23:14  授客  阅读(4188)  评论(0编辑  收藏  举报