调用第三方服务API的SDK编写思路

思路

通过将SDK方法中返回的数据划分为正常返回数据以及错误返回的数据两部分，让调用者更简单的对接口调用错误进行处理。

将SDK调用第三方服务接口的流程划分为: 数据准备，http请求，结果处理三部分，以重用代码。

例子

以聚合数据手机话费充值SDK编写为例, 手机话费充值接口

# encoding=utf-8
from urlparse import urljoin
from hashlib import md5
from datetime import datetime
from random import sample
import requests
import pytz

class APIError(object):
def __init__(self, code, msg):
self.code = code
self.message = msg

class JuhePhoneChargeApi(object):

API_PREFIX = 'https://op.juhe.cn/ofpay/mobile/'
def __init__(self, openid, key, api_entry=None):
self._key = key
self._openid = openid
self._api_entry = api_entry or self.API_PREFIX

def telcheck(self, phoneno, cardnum):
params = {'phoneno': phoneno, 'cardnum': cardnum}
return self._get(path='telcheck', params=params)

def telquery(self, phoneno, cardnum):
params = {
'phoneno': phoneno,
'cardnum': cardnum,
}
return self._get(path='telquery', params=params)

def onlineorder(self, phoneno, cardnum, orderid):
params = {
'phoneno': phoneno,
'cardnum': cardnum,
'orderid': orderid or self.create_orderid(),
}
params.update({'sign': self._create_sign(**params)})

return self._get(path='onlineorder', params=params)

def ordersta(self, orderid):
params = {'orderid': orderid}
return self._get(path='orderid', params=params)

def create_orderid(self):
return ''.join((
datetime.now(tz=pytz.timezone('Asia/Shanghai')).strftime('%Y%m%d%H%M%S%f'),
self._create_code(12)))

def _process_response(self, rsp):
"""
对第三方接口返回数据做同一处理,
:param rsp:
:return:  接口正常返回值, 错误对象
"""
if rsp.status_code != 200:
return None, APIError(rsp.status_code, 'http error')
try:
content = rsp.json()
except:
return None, APIError(99999, 'invalid rsp')
if 'error_code' in content and content['error_code'] != 0:
return None, APIError(content['error_code'], content['reason'])

return content['result'], None

def _get(self, path, params=None):
if not params:
params = {}

headers = {'Content-type': 'application/json'}
params.update({'key': self._key})

rsp = requests.get(urljoin(self._api_entry, path), params=params, headers=headers)
return self._process_response(rsp)

def _create_sign(self, phoneno, cardnum, orderid=None):
obj_str = ''.join((
self._openid,
self._key,
phoneno,
str(cardnum),
orderid or self.create_orderid()))

m = md5()
m.update(obj_str)
return m.hexdigest()

def _create_code(self, number_len):
ELEMENT = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
return ''.join(sample(ELEMENT, number_len))