让python json encode datetime类型

import json
from datetime import date, datetime


def __default(obj):
if isinstance(obj, datetime):
return obj.strftime('%Y-%m-%dT%H:%M:%S')
elif isinstance(obj, date):
return obj.strftime('%Y-%m-%d')
else:
raise TypeError('%r is not JSON serializable' % obj)

print json.dumps({'d': datetime.now(), 'today': date.today(), 'x': 111},
default=__default)