python使用json序列化datetime类型实例解析

# -*- coding: cp936 -*-
from datetime import datetime

import json

if __name__=='__main__':
 now = datetime.now()
 json.dumps({'now':now})

Traceback (most recent call last):
 File "C:\Users\xx\Desktop\t.py", line 8, in <module>
  json.dumps({'now':now})
 File "C:\Python27\lib\json\__init__.py", line 231, in dumps
  return _default_encoder.encode(obj)
 File "C:\Python27\lib\json\encoder.py", line 201, in encode
  chunks = self.iterencode(o, _one_shot=True)
 File "C:\Python27\lib\json\encoder.py", line 264, in iterencode
  return _iterencode(o, 0)
 File "C:\Python27\lib\json\encoder.py", line 178, in default
  raise TypeError(repr(o) + " is not JSON serializable")
TypeError: datetime.datetime(2012, 12, 26, 11, 51, 33, 409000) is not JSON serializable

class ComplexEncoder(json.JSONEncoder):
  def default(self, obj):
    if isinstance(obj, datetime):
      return obj.strftime('%Y-%m-%d %H:%M:%S')
    elif isinstance(obj, date):
      return obj.strftime('%Y-%m-%d')
    else:
      return json.JSONEncoder.default(self, obj)

json.dumps({'now':now}, cls=ComplexEncoder)