1 代理中介軟體
程式碼核心在於隨機選擇一條代理的ip和port，至於代理ip和port的來源，可以是購買的ip代理，也可以從網上爬取的。

# -*- coding: utf-8 -*-
'''
Created on 2017年6月14日

@author: dzm
'''
from eie.middlewares import udf_config
from eie.service.EieIpService import EieIpService

logger = udf_config.logger
eieIpService = EieIpService()

class ProxyMiddleware
 
(object):
    '''
    ip代理中介軟體
    '''

    def process_request(self,request,spider):
        '''
                        在請求上新增ip代理
        '''
        if request.url.startswith('http://'):
            proxy = eieIpService.select_rand('HTTP')
            if proxy:
                proxies = 'http://{}:{}'
 
.format(proxy['ip'],proxy['port'])
            else:
                raise Exception('沒有找到合適的IP代理')
        else:
            proxy = eieIpService.select_rand('HTTPS')
            if proxy:
                proxies = 'https://{}:{}'.format(proxy['ip'],proxy['port'])
            else:
                raise
 
 Exception('沒有找到合適的IP代理')
        request.meta['proxy'] = proxies

2 settings配置
這裡需要注意RetryMiddleware和ProxyMiddleware之間的順序，否則會出現Python Scrapy不重試連線超時，scrapy會一致超時重連，我找遍QQ群，也沒人回答我的問題。
中介軟體的順序很重要，詳細描述可以參考：SCRAPY中DOWNLOADER_MIDDLEWARES中介軟體的配置順序

DOWNLOADER_MIDDLEWARES = {
    'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware':None,
    'eie.middlewares.random_user_agent.RandomUserAgent': 100,
    'eie.middlewares.proxy_middleware.ProxyMiddleware': 110,
    'scrapy.downloadermiddlewares.retry.RetryMiddleware':120,
    'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware': 130,
}

可供參考的順序

DOWNLOADER_MIDDLEWARES_BASE
{
    'scrapy.contrib.downloadermiddleware.robotstxt.RobotsTxtMiddleware': 100,
    'scrapy.contrib.downloadermiddleware.httpauth.HttpAuthMiddleware': 300,
    'scrapy.contrib.downloadermiddleware.downloadtimeout.DownloadTimeoutMiddleware': 350,
    'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware': 400,
    'scrapy.contrib.downloadermiddleware.retry.RetryMiddleware': 500,
    'scrapy.contrib.downloadermiddleware.defaultheaders.DefaultHeadersMiddleware': 550,
    'scrapy.contrib.downloadermiddleware.redirect.MetaRefreshMiddleware': 580,
    'scrapy.contrib.downloadermiddleware.httpcompression.HttpCompressionMiddleware': 590,
    'scrapy.contrib.downloadermiddleware.redirect.RedirectMiddleware': 600,
    'scrapy.contrib.downloadermiddleware.cookies.CookiesMiddleware': 700,
    'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 750,
    'scrapy.contrib.downloadermiddleware.chunked.ChunkedTransferMiddleware': 830,
    'scrapy.contrib.downloadermiddleware.stats.DownloaderStats': 850,
    'scrapy.contrib.downloadermiddleware.httpcache.HttpCacheMiddleware': 900,
}

3 檢查ip代理是否成功
從下圖的response可以看出確實是採用了代理地址

4 代理的作用
ip代理及其作用與使用方法
使用代理IP的優缺點？
5 獲取隨機代理

def select_rand_zhimadaili(self):
        '''
                        從芝麻代理中獲取ip代理清單
        @see: http://http.zhimadaili.com/index/api/newapi.html
        '''
        try:
            proxy_keys_list = self.redis.keys()
            if proxy_keys_list:
                key_list = range(1, len(proxy_keys_list))
                key = key_list[random.choice(key_list)]
#                 proxy_list = json.load(self.redis.get(proxy_keys_list[key]))
                strs = self.redis.get(proxy_keys_list[key])
                return eval(strs)
            else:
                socket = urllib2.urlopen('http://http.zhimadaili.com/index/api/new_get_use_ips.html?num=20&type=2&pro=0&city=0&yys=0&port=1&time=1')
                result = socket.read()
                result = json.loads(result)
                proxy_list = result['data']
                for proxy in proxy_list:
                    name = '{}:{}'.format(proxy['ip'],proxy['port'])
                    self.redis.setex(name, proxy, 600)
                socket.close()
                key_list = range(1, len(proxy_list))
                key = key_list[random.choice(key_list)]
                return proxy_list[key]
        except Exception,e:
            logger.error('請求zhimadaili.com獲取代理失敗,失敗原因:%s' % e)

下面的方式是從資料庫中隨機找一條,資料庫是mysql

def select_rand_db(self,types=None):
        if types:
            sql = "select ip,port,types from eie_ip where types='{}' order by rand() limit 1".format(types)
        else:
            sql = "select ip,port,types from eie_ip order by rand() limit 1 "
        df = pd.read_sql(sql,self.engine)
        results = json.loads(df.to_json(orient='records'))
        if results and len(results)==1:
            return results[0]
        return None