python爬虫使用urllib库实现多线程下载器，下载百度异步AJAX接口图片

1、爬取下载百度图片线程类定义

# 批量采集百度图库图片数据
import re
import requests
import threading
import urllib.request,urllib.response
import uuid
import time

from day17.demo04_python_logging import *

# 定义下载器线程
class Downloader(threading.Thread):
    def __init__(self, url, fileName):
        threading.Thread.__init__(self)
        self.__url = url
        self.__fileName = fileName
        pass

    # 重写run方法
    def run(self):
        # 获得资源文件名称和资源信息（封装在响应头）
        try:
            fileName, headers = urllib.request.urlretrieve(self.__url)
            print("正在下载:")
            urllib.request.urlretrieve(self.__url, self.__fileName, self.download)
            print("下载完成！")
        except Exception as e:
            logger.error("下载文件失败:" + url )
            pass

        pass

    @staticmethod
    def download(bockNum, blockSize, contentLength):
        p = 100*bockNum*blockSize/contentLength
        if p > 100:
            p = 100
        print("下载进度{0}%".format(p))
        pass
    pass


def decode_url(url):

    """
    对百度加密后的地址进行解码\n
    :param url:百度加密的url\n
    :return:解码后的url
    """
    table = {'w': "a", 'k': "b", 'v': "c", '1': "d", 'j': "e", 'u': "f", '2': "g", 'i': "h",
             't': "i", '3': "j", 'h': "k", 's': "l", '4': "m", 'g': "n", '5': "o", 'r': "p",
             'q': "q", '6': "r", 'f': "s", 'p': "t", '7': "u", 'e': "v", 'o': "w", '8': "1",
             'd': "2", 'n': "3", '9': "4", 'c': "5", 'm': "6", '0': "7",
             'b': "8", 'l': "9", 'a': "0", '_z2C$q': ":", "_z&e3B": ".", 'AzdH3F': "/"}

    url = re.sub(r'(?P_z2C\$q|_z\&e3B|AzdH3F+)', lambda matched: table.get(matched.group('value')), url)
    return re.sub(r'(?P[0-9a-w])', lambda matched: table.get(matched.group('value')), url)


#
if __name__ == "__main__":

    pn = 0

    # 初始化url地址
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:23.0) Gecko/20100101 Firefox/23.0'
    }

    # 通过对比两个网址可以发现只有pn和gsm的值发生了改变。pn代表的是页数，rn代表每页显示的图片数量。gsm是pn 的 16位显示。
    while True:

        url = "https://image.baidu.com/search/acjson?tn=resultjson_com&ipn=rj&" \
              "ct=201326592&is=&fp=result&queryWord=汽车&cl=2&lm=&ie=utf-8&oe=utf-8&adpicid=&st=-1&z=&ic=&hd=" \
              "&latest=©right=&word=汽车&s=&se=&tab=&width=&height=&face=0" \
              "&istype=2&qc=&nc=1&fr=&expermode=&pn={0}&rn=30&gsm={1}&1545483113251=".format(pn, (str(hex(pn)))[2:])

        print(url)
        try:
            response = requests.get(url, headers= headers)

            obj = response.json()

            for temp in obj['data']:
                if temp.get('objURL'):
                    imgURL = temp['objURL']
                    if imgURL.startswith('ippr_z2C'):  # endswith
                        imgURL = decode_url(imgURL)
                        pass
                    downloader = Downloader(imgURL, str(uuid.uuid4()) + '.jpg')
                    downloader.start()
                    pass
                pass
            time.sleep(10)
            pn += 30
        except Exception as e:
            logger.error("URL地址访问数据异常：" + url)
            pass

    pass