1，从官方文档学习模块：
调用help函数，可以看到一个函数或者方法的字符串文档
help(name) 很详细的模块文档
help(range) 很详细的类的文档
help(time.localtime()) 很详细的函数文档
举例：
print(time.__doc__) 较详细的模块文档
print(time.localtime().__doc__) 较详细的函数文档
print(range.__doc__) 较详细的类的文档
使用dir可以查看模块或对象都有哪些方法：
dir(requests) 将requests模块的方法显示出来
print(dri(time)) 简略的模块函数显示
print(dir(time.localtime())) 简略的函数参数显示
print(dir(range)) 简略的类构造函数参数显示
使用ipython+?查看：
requests.get?
Python中官方文档：https://docs.python.org/zh-cn/3
Pytcharm中查看快速帮助和Python官方帮助文档：
把光标放在要查询的对象上，打开视图菜单，quick definition查看对象的定义
quick documentation 快速文档，这个是jet brains自己对Python的解释文档
第三个external documentation 外部文档，这个是Python的官方帮助文档，跳转到网页帮助文档中。
2，实战爬取数据：
1.爬取图片：
1.思路：
根据我们输入的关键字在百度进行抓取图片并下载，最后给我们推荐：
所需模块：
import re 筛选所要的内容
import requests 网路请求模块[获取网页信息]
from urllib import error 异常模块
from bs4 import BeautifulSoup 解析网页内容
import os 文件操作模块
2.代码实现：
import re
import requests
from urllib import error
from bs4 import BeautifulSoup
import osnum = 0
numPicture = 0
file = ' '
List = []def Find(url):global Listprint('正在检测图片总数量，稍等...')t = 0i = 1s = 0while t < 1000:Url = url +str(t)try:Result = requests.get(Url,timeout = 7)except BaseException:t = t + 60continueelse:result = Result.textpic_url = re.findall('"objURL":"(.*?)",',result,re.S)s += len(pic_url)if len(pic_url) == 0:breakelse:List.append(pic_url)t = t + 60return sdef recommend(url):Re = []try:html = requests.get(url)except error.HTTPError as e:returnelse:html.encoding = 'utf-8'bsobj = BeautifulSoup(html.text,'html.parser')div = bsobj.find('div',id='topRS')if div is not None:listA = div.findAll('a')for i in listA:if i is not None:Re.append(i.get_text())return Redef dowmloadPicture(html,keyword):global numpic_url = re.findall('"objURL":"(.*?)",',html,re.S)print('找到关键词：' + keyword + '的图片，即将开始下载...')for each in pic_url:print('正在下载第' + str(num + 1) + '张图，图片地址：' + str(each))try:if each is not None:pic = requests.get(each,timeout=7)else:continueexcept BaseException:print('错了，当前图片不能下载')continueelse:string = file + r'\\' +keyword + '_' +str(num) +'.jpg'fp = open(string,'wb')fp.write(pic.content)fp.close()num += 1if num >= numPicture:returnif __name__ == '__main__':word = input("请输入搜索关键词(可以是人名，地名等):")url='http://image.baidu.com/search/flip?tn=baiduimage&ie=utf-8&word='+word+'&pn='tot=Find(url)Recommend=recommend(url)# 记录相关推荐print('经过检测%s类图片共有%d张'%(word,tot))numPicture=int(input('请输入想要下载的图片数量'))file=input('请建立一个存储图片的文件夹，输入文件夹名称即可')y=os.path.exists(file)if y == 1:print('该文件已存在，请重新输入')file=input('请建立一个存储图片的文件夹,输入文件夹名称即可')else:os.mkdir(file)# while True:# file = input('请建立一个存储图片的文件夹，输入文件夹名称即可')# if os.path.exists(file):# continue# else:# break# file = 'D:/pythonlianxi/web_png't=0tmp=urlwhile t< numPicture:try:url=tmp + str(t)result=requests.get(url,timeout=10)print(url)except error.HTTPError as e:print('网络错误，请调整网络后重试')t = t+60else:dowmloadPicture(result.text,word)t = t + 60print('你还想看')for re in Recommend:print(re,end=" ")3.爬取URL：
1.代码实现：
使用命令： web_pc.py -p 页数 -t 线程 -o 文件名 关键词
解释：
web_pc.py：文件名称
关键字：可是使用Google Hacking语法
import requests,re,threading,time
from bs4 import BeautifulSoup as bs
from queue import Queue
from argparse import ArgumentParserarg = ArgumentParser(description='baidu_url_collection')
arg.add_argument('keyword',help='inurl:.asp?id=1')
arg.add_argument('-p', '--page', help='page count', dest='pagecount', type=int)
arg.add_argument('-t', '--thread', help='the thread_count', dest='thread_count', type=int, default=10)
arg.add_argument('-o', '--outfile', help='the file save result', dest='outfile', default='result.txt')
result = arg.parse_args()headers = {'User-Agent':'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; The World)'}class Bd_url(threading.Thread):def __init__(self, que):threading.Thread.__init__(self)self._que = quedef run(self):while not self._que.empty():URL = self._que.get()try:self.bd_url_collect(URL)except Exception as e:print ('Exception: ',e)passdef bd_url_collect(self, url):r = requests.get(url, headers=headers, timeout=5)soup = bs(r.content, 'lxml', from_encoding='utf-8')bqs = soup.find_all(name='a', attrs={'data-click':re.compile(r'.'), 'class':None})for bq in bqs:r = requests.get(bq['href'], headers=headers, timeout=5)if r.status_code == 200:print(r.url)with open(result.outfile, 'a+') as f:f.write(r.url + '\n')# result.outfile.close()def main():thread = []thread_count = result.thread_countque = Queue()for i in range(0,(result.pagecount)):que.put('https://www.baidu.com/s?wd=' + result.keyword + '&pn=' + str(i))for i in range(thread_count):thread.append(Bd_url(que))for i in thread:i.start()for i in thread:i.join()if __name__ == '__main__':start = time.perf_counter()main()end = time.perf_counter()
