(转载)python爬虫入门

转载地址: http://blog.csdn.net/bo_wen_/article/details/50868339

步骤1: 安装2个包

            requests和beautifulsoup

步骤2:导入代码,并执行

    

import requests
import csv
import random
import time
import socket
import http.client
# import urllib.request
from bs4 import BeautifulSoup

def get_content(url , data = None):
    header={
        'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
        'Accept-Encoding': 'gzip, deflate, sdch',
        'Accept-Language': 'zh-CN,zh;q=0.8',
        'Connection': 'keep-alive',
        'User-Agent': 'Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.235'
}
    timeout = random.choice(range(80, 180))
    while True:
        try:
            rep = requests.get(url,headers = header,timeout = timeout)
            rep.encoding = 'utf-8'
# req = urllib.request.Request(url, data, header)
            # response = urllib.request.urlopen(req, timeout=timeout)
            # html1 = response.read().decode('UTF-8', errors='ignore')
            # response.close()
break
# except urllib.request.HTTPError as e:
        #         print( '1:', e)
        #         time.sleep(random.choice(range(5, 10)))
        #
        # except urllib.request.URLError as e:
        #     print( '2:', e)
        #     time.sleep(random.choice(range(5, 10)))
except socket.timeout as e:
            print( '3:', e)
            time.sleep(random.choice(range(8,15)))

        except socket.error as e:
            print( '4:', e)
            time.sleep(random.choice(range(20, 60)))

        except http.client.BadStatusLine as e:
            print( '5:', e)
            time.sleep(random.choice(range(30, 80)))

        except http.client.IncompleteRead as e:
            print( '6:', e)
            time.sleep(random.choice(range(5, 15)))

    return rep.text
    # return html_text
def get_data(html_text):
    final = []
    bs = BeautifulSoup(html_text, "html.parser")  # 创建BeautifulSoup对象
body = bs.body # 获取body部分
data = body.find('div', {'id': '7d'})  # 找到id为7d的div
ul = data.find('ul')  # 获取ul部分
li = ul.find_all('li')  # 获取所有的li
for day in li: # 对每个li标签中的内容进行遍历
temp = []
        date = day.find('h1').string  # 找到日期
temp.append(date)  # 添加到temp中
inf = day.find_all('p')  # 找到li中的所有p标签
temp.append(inf[0].string,)  # 第一个p标签中的内容（天气状况）加到temp中
if inf[1].find('span') is None:
            temperature_highest = None # 天气预报可能没有当天的最高气温（到了傍晚，就是这样），需要加个判断语句,来输出最低气温
else:
            temperature_highest = inf[1].find('span').string  # 找到最高温
temperature_highest = temperature_highest.replace('℃', '')  # 到了晚上网站会变，最高温度后面也有个℃
temperature_lowest = inf[1].find('i').string  # 找到最低温
temperature_lowest = temperature_lowest.replace('℃', '')  # 最低温度后面有个℃，去掉这个符号
temp.append(temperature_highest)   # 将最高温添加到temp中
temp.append(temperature_lowest)   #将最低温添加到temp中
final.append(temp)   #将temp加到final中
return final

def write_data(data, name):
    file_name = name
    with open(file_name, 'a', errors='ignore', newline='') as f:
            f_csv = csv.writer(f)
            f_csv.writerows(data)

if __name__ == '__main__':
                url = 'http://www.weather.com.cn/weather/101190401.shtml'
html = get_content(url)
                result = get_data(html)
                write_data(result, 'weather.csv')

步骤3: 结果如下:

23日（今天）	多云	19	12
24日（明天）	多云	20	12
25日（后天）	多云	21	14
26日（周四）	多云	21	14
27日（周五）	多云	22	14
28日（周六）	多云	21	15
29日（周日）	多云转晴	21	11