Python如何比对返回的报文

Python比对返回的报文可以使用多种方法，包括字符串比较、正则表达式、JSON解析与比对、XML解析与比对、以及专门的报文比对库等。其中，最常见的方法是字符串比较与JSON解析与比对。字符串比较适用于简单的报文内容比对，JSON解析与比对适用于结构化数据报文。以下将详细介绍JSON解析与比对的方法。

JSON解析与比对的方法：

解析报文为JSON对象：使用Python的json模块将报文解析为JSON对象。
比对JSON对象：遍历JSON对象，逐一比对各个字段的值。
提取差异：记录并输出不相同的字段及其值。

一、解析报文为JSON对象

Python提供了一个内置的json模块，可以方便地进行JSON数据的解析与生成。首先，我们需要将返回的报文解析为JSON对象。

import json
def parse_json_response(response):
    try:
        return json.loads(response)
    except json.JSONDecodeError as e:
        print(f"Error decoding JSON: {e}")
        return None

二、比对JSON对象

一旦我们将报文解析为JSON对象，接下来就可以进行比对。比对的方式可以是递归遍历所有的键值对，并记录所有的差异。

def compare_json_objects(json1, json2, path=""):
    differences = []
    if isinstance(json1, dict) and isinstance(json2, dict):
        for key in json1:
            if key in json2:
                sub_diffs = compare_json_objects(json1[key], json2[key], path + f".{key}")
                differences.extend(sub_diffs)
            else:
                differences.append(f"Key {path}.{key} is missing in the second JSON")
        for key in json2:
            if key not in json1:
                differences.append(f"Key {path}.{key} is missing in the first JSON")
    elif isinstance(json1, list) and isinstance(json2, list):
        for index, (item1, item2) in enumerate(zip(json1, json2)):
            sub_diffs = compare_json_objects(item1, item2, path + f"[{index}]")
            differences.extend(sub_diffs)
        if len(json1) != len(json2):
            differences.append(f"Lists at {path} have different lengths")
    else:
        if json1 != json2:
            differences.append(f"Value at {path} differs: {json1} != {json2}")
    return differences

三、提取差异

最后，将所有的差异记录并输出。

def main():
    response1 = '{"name": "John", "age": 30, "city": "New York"}'
    response2 = '{"name": "John", "age": 31, "city": "New York", "country": "USA"}'
    json1 = parse_json_response(response1)
    json2 = parse_json_response(response2)
    if json1 and json2:
        differences = compare_json_objects(json1, json2)
        if differences:
            print("Differences found:")
            for diff in differences:
                print(diff)
        else:
            print("No differences found")
if __name__ == "__main__":
    main()

四、字符串比较

字符串比较是最简单的报文比对方法，适用于简单报文内容比对。可以直接使用Python的字符串操作函数进行比较，例如==操作符、split函数、以及re正则表达式模块。

字符串比较示例

response1 = "name=John&age=30&city=New York"
response2 = "name=John&age=31&city=New York"
if response1 == response2:
    print("The responses are identical")
else:
    print("The responses are different")

使用正则表达式进行字符串比对

正则表达式可以用来匹配复杂的字符串模式，从而进行更细粒度的报文内容比对。

import re
pattern = r"name=(\w+)&age=(\d+)&city=([\w\s]+)"
match1 = re.match(pattern, response1)
match2 = re.match(pattern, response2)
if match1 and match2:
    if match1.groups() == match2.groups():
        print("The responses match the pattern and are identical")
    else:
        print("The responses match the pattern but are different")
else:
    print("The responses do not match the pattern")

五、XML解析与比对

对于XML格式的报文，可以使用Python的xml.etree.ElementTree模块进行解析与比对。

解析XML报文

import xml.etree.ElementTree as ET
def parse_xml_response(response):
    try:
        return ET.fromstring(response)
    except ET.ParseError as e:
        print(f"Error parsing XML: {e}")
        return None

比对XML节点

类似于JSON比对，可以递归遍历XML节点，并记录所有的差异。

def compare_xml_elements(elem1, elem2, path="/"):
    differences = []
    if elem1.tag != elem2.tag:
        differences.append(f"Different tags at {path}: {elem1.tag} != {elem2.tag}")
    if elem1.text != elem2.text:
        differences.append(f"Different text at {path}: {elem1.text} != {elem2.text}")
    if elem1.attrib != elem2.attrib:
        differences.append(f"Different attributes at {path}: {elem1.attrib} != {elem2.attrib}")
    children1 = list(elem1)
    children2 = list(elem2)
    for index, (child1, child2) in enumerate(zip(children1, children2)):
        sub_diffs = compare_xml_elements(child1, child2, path + f"{elem1.tag}[{index}]/")
        differences.extend(sub_diffs)
    if len(children1) != len(children2):
        differences.append(f"Different number of children at {path}: {len(children1)} != {len(children2)}")
    return differences

提取差异

def main():
    response1 = "<person><name>John</name><age>30</age><city>New York</city></person>"
    response2 = "<person><name>John</name><age>31</age><city>New York</city><country>USA</country></person>"
    xml1 = parse_xml_response(response1)
    xml2 = parse_xml_response(response2)
    if xml1 and xml2:
        differences = compare_xml_elements(xml1, xml2)
        if differences:
            print("Differences found:")
            for diff in differences:
                print(diff)
        else:
            print("No differences found")
if __name__ == "__main__":
    main()

六、专门的报文比对库

Python社区提供了一些专门用于报文比对的库，例如DeepDiff、JsonDiff、xmltodict等。这些库提供了更高级的功能，可以简化报文比对的过程。

使用DeepDiff进行JSON比对

DeepDiff是一个功能强大的库，用于比较复杂的Python对象，包括JSON数据。

from deepdiff import DeepDiff
response1 = '{"name": "John", "age": 30, "city": "New York"}'
response2 = '{"name": "John", "age": 31, "city": "New York", "country": "USA"}'
json1 = json.loads(response1)
json2 = json.loads(response2)
diff = DeepDiff(json1, json2)
if diff:
    print("Differences found:")
    print(diff)
else:
    print("No differences found")

使用xmltodict进行XML比对

xmltodict是一个将XML数据转换为Python字典的库，可以结合DeepDiff进行XML比对。

import xmltodict
from deepdiff import DeepDiff
response1 = "<person><name>John</name><age>30</age><city>New York</city></person>"
response2 = "<person><name>John</name><age>31</age><city>New York</city><country>USA</country></person>"
xml1 = xmltodict.parse(response1)
xml2 = xmltodict.parse(response2)
diff = DeepDiff(xml1, xml2)
if diff:
    print("Differences found:")
    print(diff)
else:
    print("No differences found")