import urllib.request
import urllib.parse

url =r"http://www.baidu.com"
#将要发送的数据合成一个字典
#字典的键值在网页里找
data = {
    "username":"1507",
    "password":"230063"
}
#对要发送的数据进行打包
postData = urllib.parse.urlencode(data).encode("utf-8")  #要对发送的数据包编码成二进制字节

#请求体
req = urllib.request.Request(url,data=postData)
#req.add_header("User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36")

#请求
response =urllib.request.urlopen(req)
data2 = response.read()

#将文件保存到本地
url2 = "baidu.html"
with open(url2,"wb") as  f:
    f.write(data2)