三分钟带你学会爬虫

## 深度学习模型训练极大的依赖数据，当数据量不够时，可通过网络爬虫从网上爬取数据。下面以爬取刘亦菲和刘德华图片数据为例介绍爬虫：

## 代码使用步骤如下：

1. 在name.txt中输入你要爬取的关键词，我输入的为刘亦菲和刘德华（不用创建文件夹，文件夹是代码生成的）。

刘亦菲
刘德华

import re
import requests
from urllib import error
from bs4 import BeautifulSoup
import os

num = 0
numPicture = 0
file = ''
List = []


def Find(url):
    global List
    print('正在检测图片总数，请稍等.....')
    t = 0
    i = 1
    s = 0
    while t < 1000:
        Url = url + str(t)
        try:
            Result = requests.get(Url, timeout=7)
        except BaseException:
            t = t + 60
            #import pdb;pdb.set_trace()
            continue
        else:
            result = Result.text
            pic_url = re.findall('"objURL":"(.*?)",', result, re.S)  # 先利用正则表达式找到图片url
            s += len(pic_url)
            if len(pic_url) == 0:
                #import pdb;pdb.set_trace()
                break
            else:
                List.append(pic_url)
                t = t + 60
    return s


def recommend(url):
    Re = []
    try:
        html = requests.get(url)
    except error.HTTPError as e:
        return
    else:
        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 Re


def dowmloadPicture(html, keyword):
    global num
    # t =0
    pic_url = re.findall('"objURL":"(.*?)",', html, re.S)  # 先利用正则表达式找到图片url
    print('找到关键词:' + keyword + '的图片，即将开始下载图片...')
    for each in pic_url:
        print('正在下载第' + str(num + 1) + '张图片，图片地址:' + str(each))
        try:
            if each is not None:
                pic = requests.get(each, timeout=7)
            else:
                continue
        except BaseException:
            print('错误，当前图片无法下载')
            continue
        else:
            string = os.path.join(file, str(num) + '.jpg')
            fp = open(string, 'wb')
            fp.write(pic.content)
            fp.close()
            num += 1
        if num >= numPicture:
            return


if __name__ == '__main__':
    tm = int(input('请输入每类图片的下载数量 '))
    numPicture = tm
    line_list = []
    with open('name.txt', encoding='utf-8') as file:
        line_list = [k.strip() for k in file.readlines()]

    #import pdb;pdb.set_trace()
    for word in line_list:
        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))
        file = word
        y = os.path.exists(file)
        if y == 1:
            print('该文件已存在，请重新输入')
            file = word
            os.mkdir(file)
        else:
            os.mkdir(file)
        t = 0
        tmp = url
        while 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 + 60
            else:
                dowmloadPicture(result.text, word)
                t = t + 60
        numPicture = numPicture + tm

    print('任务完成')

2. 运行代码：python3 spider.py

    会提示你输入的数量，结果如下：    

3. 结果新建了两个文件夹，刘亦菲和刘德华。

4. 文件夹里的内容如下：