調用第三方服務API的SDK編寫思路

思路

1. 通過將SDK方法中返回的數據劃分爲正常返回數據以及錯誤返回的數據兩部分，讓調用者更簡單的對接口調用錯誤進行處理。
2. 將SDK調用第三方服務接口的流程劃分爲: 數據準備，http請求，結果處理三部分，以重用代碼。

例子

以聚合數據手機話費充值SDK編寫爲例, 官方文檔

# 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):
        """
        對第三方接口返回數據做同一處理,
        :param rsp:
        :return:  接口正常返回值, 錯誤對象
        """
        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))

文／Ljian1992（簡書作者）
原文鏈接：http://www.jianshu.com/p/08f783dea4d9