Python实现字典转字符串的五种方法

import json
 
my_dict = {"key1": "value1", "key2": "value2"}
 
# 方法1：使用json模块的dumps方法
dict_str = json.dumps(my_dict)
print(dict_str)

my_dict = {"key1": "value1", "key2": "value2"}
 
# 方法2：使用str方法
dict_str = str(my_dict)
print(dict_str)

my_dict = {"key1": "value1", "key2": "value2"}
 
# 方法3：使用循环和字符串拼接
dict_str = "{"
for key, value in my_dict.items():
    dict_str += "'" + key + "': '" + value + "', "
dict_str = dict_str.rstrip(", ") + "}"
print(dict_str)

my_dict = {"key1": "value1", "key2": "value2"}
 
# 方法4：使用字符串的format方法
dict_str = "{{'{}': '{}', '{}': '{}'}}".format(*my_dict.items())
print(dict_str)

my_dict = {"key1": "value1", "key2": "value2"}
 
# 方法5：使用字符串的join方法
dict_str = '{' + ', '.join("'{}': '{}'".format(key, value) for key, value in my_dict.items()) + '}'
print(dict_str)

user_info = '{"name" : "john", "gender" : "male", "age": 28}'

user_dict = {"name" : "john", "gender" : "male", "age": 28}

>>> import json
>>> user_info= '{"name" : "john", "gender" : "male", "age": 28}'
>>> user_dict = json.loads(user_info)
>>> user_dict
{u'gender': u'male', u'age': 28, u'name': u'john'}

>>> import json
>>> user_info = "{'name' : 'john', 'gender' : 'male', 'age': 28}"
# 由于字符串使用单引号，会导致运行出错
>>> user_dict = json.loads(user_info)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/decoder.py", line 380, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Expecting property name: line 1 column 2 (char 1)

>>> usr_info = '{"name" : "john", "gender" : "male", "age": 28}'
>>> user_dict = eval(user_info)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}
>>> user_info = "{'name' : 'john', 'gender' : 'male', 'age': 28}"
>>> user_dict = eval(user_info)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}

# 让用户输入 `user_info`
>>> user_info = raw_input('input user info: ')
# 输入 {"name" : "john", "gender" : "male", "age": 28}，没问题
>>> user_dict = eval(user_info)
# 输入 __import__('os').system('dir')，user_dict 会列出当前的目录文件！
# 再输入一些删除命令，则可以把整个目录清空了！
>>> user_dict = eval(user_info)

>>> import ast
>>> user = '{"name" : "john", "gender" : "male", "age": 28}'
>>> user_dict = ast.literal_eval(user)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}
user_info = "{'name' : 'john', 'gender' : 'male', 'age': 28}"
>>> user_dict = ast.literal_eval(user)
>>> user_dict
{'gender': 'male', 'age': 28, 'name': 'john'}