python模块之json

            dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,allow_nan=True, cls=None, indent=None, separators=None,default=None, sort_keys=False, **kw):
# 序列号 “obj” 数据类型 转换为 JSON格式的字符串

dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,allow_nan=True, cls=None, indent=None, separators=None,default=None, sort_keys=False, **kw):
""" 有两个动作，一个动作是将”obj“转换为JSON格式的字符串，一个动作是将字符串写入到文件中，也就是说文件描述符fp是必须要的参数 """

            import json

print(json.dumps([]))
print(json.dumps(1))
print(json.dumps("1"))
dict1 = {1:"one",2:"two",3:"three"}
print(json.dumps(dict1))

with open("test.json","w",encoding="utf-8") as f:
    f.write("this is dumps\n")
    f.write(json.dumps(dict1,indent=4)) #1使用dumps
    f.write("\n")
    f.write("this is dump\n")
json.dump(dict1,f,indent=4)  #2使用dump，与1效果一致
#格式化：indent=4

this is dumps
{
    "1": "one",
    "2": "two",
    "3": "three"
}
this is dump
{
    "1": "one",
    "2": "two",
    "3": "three"
}

            loads(s, encoding=None, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)
""" 将包含str类型的JSON文档反序列化为一个python对象"""

load(fp, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)
"""将一个包含JSON格式数据的可读文件饭序列化为一个python对象"""

            import json

json_l = json.loads(‘{"1": "one", "2": "two", "3": "three"}‘)
print(type(json_l),json_l)

json_2 ={"1": "one", "2": "two", "3": "three"}
with open("test.json","w",encoding="utf-8") as f:
    f.write(json.dumps(json_2,indent=4)) #1使用dumps

with open("test.json","r",encoding="utf-8") as f:
    aa= json.loads(f.read())  # 与 json.loads(f.read())
    f.seek(0) #将光标移动到起始位置
    bb = json.load(f)
print(type(aa),aa)
print(type(bb),bb)执行结果：

json.JSONDecoder([encoding[, object_hook[, parse_float[, parse_int[, parse_constant[, strict[, object_pairs_hook]]]]]]])

json.JSONEncoder([skipkeys[, ensure_ascii[, check_circular[, allow_nan[, sort_keys[, indent[, separators[, encoding[, default]]]]]]]]])

            import json
data = [{ ‘a‘ : 1, ‘b‘ : 2, ‘c‘ : 3, ‘d‘ : 4, ‘e‘ : 5 }]

json = json.JSONEncoder().encode(data)
print (type(json),json)

            import json

data1 = {1:"one",2:"two",3:"three"}
json_string=json.dumps(data1)

with open("test1.json","w",encoding="utf-8") as f:  #将json_string写入到文件中
    f.write(json.dumps(json_string,indent=4))

with open("test1.json","r",encoding="utf-8") as f2: #读取json文件
    f2.seek(0)
    aa= json.loads(f2.read())

json2 = json.JSONDecoder().decode(aa) #json
print (type(json2),json2)