6.python3爬虫之urllib库

# 导入urllib.request
import urllib.request

# 向指定的url发送请求，并返回服务器响应的类文件对象
response = urllib.request.urlopen("http://www.baidu.com")

# 类文件对象支持 文件对象的操作方法，如read()方法读取文件全部内容，返回字符串
html = response.read()

# 打印字符串,记得加上decode(‘utf-8‘)方法，就不会出现\n\n
print(html.decode(‘utf-8‘))

import urllib.request

url = "http://www.itcast.cn"

#User-Agent是反爬虫斗争的第一步
list_headers={
"User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36"
}

#  url 连同 headers，一起构造Request请求，这个请求将附带 IE9.0 浏览器的User-Agent
request = urllib.request.Request(url, headers = list_headers)

# 向服务器发送这个请求
response = urllib.request.urlopen(request)

html = response.read()
print(html.decode(‘utf-8‘))

#添加一个特定的header
import urllib.request

url = "http://www.itcast.cn"

#IE 9.0 的 User-Agent
header = {"User-Agent" : "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;"}
request = urllib.request.Request(url, headers = header)

#也可以通过调用Request.add_header() 添加/修改一个特定的header
request.add_header("Connection", "keep-alive")

# 也可以通过调用Request.get_header()来查看header信息
# request.get_header(header_name="Connection")

response = urllib.request.urlopen(request)

#查看响应状态码200
print(response.code)
html = response.read()

print(html.decode(‘utf-8‘))

#随机添加/修改User-Agent
import urllib.request
import random

url = "http://www.itcast.cn"

ua_list = [
    "Mozilla/5.0 (Windows NT 6.1; ) Apple.... ",
    "Mozilla/5.0 (X11; CrOS i686 2268.111.0)... ",
    "Mozilla/5.0 (Macintosh; U; PPC Mac OS X.... ",
    "Mozilla/5.0 (Macintosh; Intel Mac OS... "
]

user_agent = random.choice(ua_list)

request = urllib.request.Request(url)

#也可以通过调用Request.add_header() 添加/修改一个特定的header
request.add_header("User-Agent", user_agent)

# 第一个字母大写，后面的全部小写
request.get_header("User-agent")

response = urllib.request.urlopen(request)

html = response.read()
print(html.decode(‘utf-8‘))

from urllib import request,parse
url = "http://www.baidu.com/s"

#User-Agent是反爬虫斗争的第一步
list_headers={
"User-Agent":"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36"
}

keyword = input("请输入需要查询的关键字： ")

dict={
    ‘wd‘:keyword
}

#parse.urlencode(dict)参数为字典类型
dict=parse.urlencode(dict)
#wd=%E4%BC%A0%E6%99%BA%E6%92%AD%E5%AE%A2
print(dict)
#dict为字符类型str
print(type(dict))
fulurl=url+‘?‘+dict

print(fulurl)
#fulurl=https://www.baidu.com/s?wd=%E4%BC%A0%E6%99%BA%E6%92%AD%E5%AE%A2

req=request.Request(url=fulurl,headers = list_headers)
respose=request.urlopen(req)
print(respose.read().decode(‘utf-8‘))

import urllib
import urllib.request
from urllib import parse

def loadPage(url, filename):
    """
        作用：根据url发送请求，获取服务器响应文件
        url: 需要爬取的url地址
        filename : 处理的文件名
    """
    # print(type(filename))
    print("正在下载 " + filename)
    headers = {"User-Agent" : "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_0) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11"}

    request = urllib.request.Request(url, headers = headers)
    return urllib.request.urlopen(request).read()

def writePage(html, filename):
    """
        作用：将html内容写入到本地
        html：服务器相应文件内容
    """
    print("正在保存 " + filename)
    # 文件写入,文件打开方式有问题，把之前的打开语句修改为用二进制方式
    with open(filename, "wb+") as f:
        f.write(html)
    print("-" * 30)

def tiebaSpider(url, beginPage, endPage):
    """
        作用：贴吧爬虫调度器，负责组合处理每个页面的url
        url : 贴吧url的前部分
        beginPage : 起始页
        endPage : 结束页
    """
    for page in range(beginPage, endPage + 1):
        pn = (page - 1) * 50
        filename = "第" + str(page) + "页.html"
        # print(type(filename))
        fullurl = url + "&pn=" + str(pn)
        html = loadPage(fullurl, filename)
        writePage(html, filename)
        print("谢谢使用")

if __name__ == "__main__":
    kw = input("请输入需要爬取的贴吧名:")
    beginPage = int(input("请输入起始页："))
    endPage = int(input("请输入结束页："))

    url = "http://tieba.baidu.com/f?"
    key = parse.urlencode({"kw": kw})
    fullurl = url + key
    tiebaSpider(fullurl, beginPage, endPage)

import urllib
import urllib.request

from urllib import parse

# POST请求的目标URL
url = "http://fanyi.youdao.com/translate?smartresult=dict&smartresult=rule&smartresult=ugc&sessionFrom=null"

headers={"User-Agent": "Mozilla...."}

#formadata为post参数

formdata = {
    "type":"AUTO",
    "i":"i love python",
    "doctype":"json",
    "xmlVersion":"1.8",
    "keyfrom":"fanyi.web",
    "ue":"UTF-8",
    "action":"FY_BY_ENTER",
    "typoResult":"true"
}

#post提交的参数为字节
data =bytes(parse.urlencode(formdata),encoding=‘utf-8‘)

request = urllib.request.Request(url,data=data, headers = headers)
response = urllib.request.urlopen(request)
print(response.read())

from urllib import parse
import urllib.request

url = "https://movie.douban.com/j/chart/top_list?type=11&interval_id=100%3A90&action"

headers = {"User-Agent" : "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36"}

formdata = {
        "start":"0",
        "limit":"20"
    }

data = bytes(parse.urlencode(formdata),encoding=‘utf-8‘)

request =urllib.request.Request(url, data = data, headers = headers)

print(urllib.request.urlopen(request).read())