比如，最简单的一个json文件

test_json = { "a": 1, "b": 2}

test_json["c"] = 3

{'a': 1, 'b': 2, 'c': 3}

import json

a_file = open("netconfig.json","r")
json_object = json.load(a_file)
a_file.close()
print(json_object)

json_object["ssid"] = "mywifi"

a_file=open("netconfig.json","w")
json.dump(json_object,a_file)
a_file.close()