import json
dic = '{"name":"alex"}'  #--->{"name":"alex"}--->'{"name":"alex"}'
i = 8       #--->'8'
s = 'hello'    #--->"hello"--->'"hello"'
l = [11,22]     #--->"[11,22]"
print(eval(dic))    --->{"name":"alex"}
dic = json.loads(dic)
print(dic["name"])  --->alex

data = json.dumps(dic)    #json字符串：所有引号变成双引号
print(data,type(data))   --->{"name": "alex"} <class 'str'>

f = open("hello","w")
f.write(data)   /    json.dump(dic,f)                      
f.close()
f = open("hello","r")
data = json.loads(f.read())    /    data = json.load(f)
f.close()
print(data["name"],type(data))   --->alex <class 'dict'>