要說python優(yōu)雅在何處惦银，與其他語言相比最為明顯的，那一定是網(wǎng)絡操作了末誓。python可以讓我們用最少的語句寫出功能強大的程序扯俱，網(wǎng)絡操作有相當多的開源庫可以使用，而不用像其他語言一樣喇澡，步驟繁瑣迅栅。接下來從低到高介紹python網(wǎng)絡編程

1. socket網(wǎng)絡編程接口
   • 基本概念
     可以這樣來理解socket溉贿，完成一段網(wǎng)絡通信需要五個元素呼畸，協(xié)議族孔飒，協(xié)議類型撬碟，協(xié)議忆植，目標ip地址业扒，目標端口號兢交，這是由TCP/IP網(wǎng)絡結(jié)構(gòu)決定的漠畜。socket作為一種數(shù)據(jù)結(jié)構(gòu)秀睛，將以上五個信息組合起來尔当，稱為套接字。根據(jù)面向連接與非連接蹂安，套接字類型分為Datagram與Stream兩種類型椭迎。Datagram套接字使用UDP協(xié)議锐帜，向目標地址發(fā)送數(shù)據(jù)包，不保證可靠送達畜号，Stream使用TCP協(xié)議缴阎，是可靠的、具有差錯與流量控制的傳輸協(xié)議简软，也就是說蛮拔，stream類型的套接字傳輸信息，具有較好的可靠性痹升，而Datagram類型的套接字具有更高的實時性语泽。
   • 初始化流式套接字的步驟
     • 服務端
       • 使用socket函數(shù)創(chuàng)建套接字
       • 綁定到指定的ip地址
       • 監(jiān)聽客戶端連接
       • 獲取客戶端連接后，使用返回的套接字收發(fā)數(shù)據(jù)
       • 通信結(jié)束视卢，關閉套接字
     • 客戶端
       • 創(chuàng)建套接字
       • 連接指定ip地址
       • 連接成功后收發(fā)數(shù)據(jù)
       • 關閉套接字

     • 常用套接字函數(shù)

       
       
       
       
     • 例程
       • 時間戳服務器

                    #!/usr/bin/env python
          import socket
          from time import ctime
          
          
          host='127.0.0.1'
          port=8000
          bufsize=1024
          addr=(host, port)
          
          sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
          sock.bind(addr)
          sock.listen(5)
          while True:
              print 'waiting for connection...'
              clisock, cliaddr = sock.accept()
              print 'connected from', cliaddr
              print 'peername:', clisock.getpeername()
              data = clisock.recv(bufsize)
              if not data:
                  break
              clisock.send('[%s] %s' % (ctime(), data))
              clisock.close()
          sock.close()
         

       • 客戶端

          #!/usr/bin/env python
          from time import ctime
          import socket
          
          host='127.0.0.1'
          port=8000
          addr=(host, port)
          bufsize=1024
          
          
          while True:
              sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
              sock.connect(addr)
              data = raw_input(u'>')
              if not data:
                  break
              sock.send(data)
              data = sock.recv(bufsize)
              print data
                     #!/usr/bin/env python
          from time import ctime
          import socket
          
          host='127.0.0.1'
          port=8000
          addr=(host, port)
          bufsize=1024
          
          
          while True:
              sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
              sock.connect(addr)
              data = raw_input(u'>')
              if not data:
                  break
              sock.send(data)
              data = sock.recv(bufsize)
              print data
          
              sock.close()
              sock.close()
         

2. 網(wǎng)絡http操作踱卵，使用urllib、urllib2据过、requests
   • 一般來說惋砂，進行網(wǎng)絡操作時可以使用以上三個模塊任意一種，但是就功能上來說绳锅，requests較為強大西饵，對底層模塊進行了封裝，使用更為簡便鳞芙，我們重點來討論一下requests
   • http請求有幾種類型眷柔，最常用的是get與post，get請求向指定的資源請求數(shù)據(jù)原朝，GET 請求可被緩存驯嘱，GET 請求保留在瀏覽器歷史記錄中，GET 請求可被收藏為書簽喳坠，GET 請求不應在處理敏感數(shù)據(jù)時使用鞠评，GET 請求有長度限制，GET 請求只應當用于取回數(shù)據(jù)壕鹉。post請求向指定的資源提交數(shù)據(jù)剃幌，POST 請求不會被緩存，POST 請求不會保留在瀏覽器歷史記錄中晾浴，POST 不能被收藏為書簽负乡，POST 請求對數(shù)據(jù)長度沒有要求。還有一個區(qū)別是脊凰，使用get請求時抖棘，參數(shù)直接顯示在url中，安全性不高，而post請求將參數(shù)包含在請求體中钉答。
   • 使用requests
     • 發(fā)出get與post請求

       In [8]: res = requests.get('http://www.baidu.com')
       In [9]: res2 = requests.post('http://www.baidu.com')
       

     • 設置請求參數(shù)，通過params參數(shù)設置請求參數(shù)杈抢，需要傳進一個字典数尿，且值為none的鍵不會出現(xiàn)在url中

       In [10]: para = {'username':'xiaozhi','password':'testpass'}
       In [11]: res3 = requests.get('http://www.baidu.com',params=para)
       In [12]: res3.url
       Out[12]: u'http://www.baidu.com/?username=xiaozhi&password=testpass'
       

     • 為post請求傳遞數(shù)據(jù)使用data參數(shù)

       In [3]: data = {'key':'value'}
       In [4]: res = requests.post('http://httpbin.org/post', data=data)
       

       In [38]: payload = (('key1', 'value1'), ('key1', 'value2'))
       In [39]: r = requests.post('http://httpbin.org/post', data=payload)
       

     • 獲取響應內(nèi)容
       字符串內(nèi)容

       In [5]: res.text
       Out[5]: u'{"args":{},"data":"","files":{},"form":{"key":"value"},"headers":{"Accept":"*/*","Accept-Encoding":"gzip, deflate","Connection":"close","Content-Length":"9","Content-Type":"application/x-www-form-urlencoded","Host":"httpbin.org","User-Agent":"python-requests/2.18.4"},"json":null,"origin":"113.140.11.6","url":"http://httpbin.org/post"}\n'
       

       查看與設置內(nèi)容編碼

       In [8]: res.encoding
       In [9]: res.encoding='utf-8'
       

       使用content屬性可以查看返回內(nèi)容的字節(jié)內(nèi)容，python會自動為我們解碼gzip壓縮的數(shù)據(jù)

       In [15]: res.content
       Out[15]: '{"args":{},"data":"","files":{},"form":{"key":"value"},"headers":{"Accept":"*/*","Accept-Encoding":"gzip, deflate","Connection":"close","Content-Length":"9","Content-Type":"application/x-www-form-urlencoded","Host":"httpbin.org","User-Agent":"python-requests/2.18.4"},"json":null,"origin":"113.140.11.6","url":"http://httpbin.org/post"}\n'
       

       json對象

       In [16]: res.json()
       Out[16]: 
       {u'args': {},
        u'data': u'',
        u'files': {},
        u'form': {u'key': u'value'},
        u'headers': {u'Accept': u'*/*',
         u'Accept-Encoding': u'gzip, deflate',
         u'Connection': u'close',
         u'Content-Length': u'9',
         u'Content-Type': u'application/x-www-form-urlencoded',
         u'Host': u'httpbin.org',
         u'User-Agent': u'python-requests/2.18.4'},
        u'json': None,
        u'origin': u'113.140.11.6',
        u'url': u'http://httpbin.org/post'}
       

       查看返回狀態(tài)碼

       res.status_code
       

       原始數(shù)據(jù)

       In [31]: res = requests.get('https://api.github.com/events', stream=True)
       
       In [32]: with open('temp.txt', 'wb') as fd:
           ...:     for chunk in res.iter_content(512):
           ...:         fd.write(chunk)
       

       查看返回的http頭部

       In [44]: r.headers
       Out[44]: {'Content-Length': '351', 'Via': '1.1 vegur', 'Server': 'gunicorn/19.8.1', 'Connection': 'keep-alive', 'Access-Control-Allow-Credentials': 'true', 'Date': 'Thu, 24 May 2018 12:13:11 GMT', 'Access-Control-Allow-Origin': '*', 'Content-Type': 'application/json'}
       

       使用headers參數(shù)定制請求頭

       In [33]: headers = {'user-agent':'myapp'}
       In [34]: res = requests.get('http://www.baidu.com', headers=headers)
       

       返回對象的cookies屬性保存了會話cookie惶楼，當需要重用cookies時右蹦，將cookie對象作為參數(shù)傳遞給請求的cookies參數(shù)

       res = requests.get(url,cookies=res.cookies)
       

       使用cookie模擬登陸豆瓣網(wǎng)站

       cookies = {}
       
       In [57]: raw_cookies='bid=-aa9Pl9eMB0; _pk_ref.100001.8cb4=%5B%22%22%2C%22%22%2C1527208498%2C%22http
           ...: s%3A%2F%2Fwww.baidu.com%2Flink%3Furl%3DFpVInsn4IT_ak-F56yaoXBUJPtBtueoUd3nVtc4NWZV4QBO8sdnc
           ...: vDJTEYLuefv5%26ck%3D1583.5.192.64.190.324.478.646%26shh%3Dwww.baidu.com%26wd%3D%26eqid%3D89
           ...: b868ea00032e0c000000035b06b157%22%5D; _pk_id.100001.8cb4=83b586dcea10d0e5.1519446169.2.1527
           ...: 209320.1519446169.; __utma=30149280.2141300691.1527208503.1527208503.1527208503.1; __utmz=3
           ...: 0149280.1527208503.1.1.utmcsr=baidu|utmccn=(organic)|utmcmd=organic; ll="118371"; _pk_ses.1
           ...: 00001.8cb4=*; __utmb=30149280.9.10.1527208503; __utmc=30149280; ps=y; push_noty_num=0; push
           ...: _doumail_num=0; __utmv=30149280.13784; ap=1; dbcl2="137847261:LmaeCQEh7Eo"; ck=x-vi; __utmt
           ...: =1'
       
       In [58]: for line in raw_cookies.split(';'):
           ...:     key,value = line.split('=', 1)
           ...:     cookies[key] = value
       In [64]: url = 'https://www.douban.com/people/xiaozhiAXX/'
       
       In [65]: res = requests.get(url,cookies=cookies)
       
       In [66]: res.status_code
       Out[66]: 200
       
       

       使用proxies參數(shù)設置代理,訪問google

       In [1]: import requests
       
       In [2]: proxy = {'http':'http://127.0.0.1:8118','https':'https://127.0.0.1:8118'}
       
       In [3]: res = requests.get('https://www.google.com', proxies=proxy)
       
       In [4]: res.status_code
       Out[4]: 200
       

3. 網(wǎng)絡客戶端
   • 電子郵件
     python發(fā)送電子郵件時，使用標準庫中的smtplib和email歼捐，smptlib中有一個SMTP類何陆，需要發(fā)送郵件時，初始化該類返回smtpserver對象豹储，使用login登陸MUA贷盲，使用sendmail方法發(fā)送郵件，郵件的正文用email.mime.text.MIMEText對象進行描述
     簡單電子郵件發(fā)送程序

     from email.mime.text import MIMEText
     msg = MIMEText('hello message','plain', 'utf-8')
     from_addr = 'yourPhone@163.com'
     to_addr = 'yourQQ@qq.com'
     sub_msg = 'hello'
     smtp_server = 'smtp.163.com'
     import smtplib
     # 初始化smtp對象剥扣，傳入服務器地址與端口號
     server = smtplib.SMTP(smtp_server,25)
     # 設置調(diào)試模式可以讓我們看到發(fā)送郵件過程中的信息
     server.set_debuglevel(1)
     # 登陸MUA巩剖，使用賬戶與授權(quán)碼登陸
     server.login(from_addr, 'yourpassword')
     msg['From'] = from_addr
     msg['To'] = to_addr
     msg['Subject'] = 'important message'
     server.sendmail(from_addr, [to_addr], msg.as_string())
     

     郵件被放入垃圾郵件中，如下

     
     
     
     

     發(fā)送帶附件的電子郵件

      from email.mime.text import MIMEText
      from smtplib import SMTP
      from email.mime.multipart import MIMEMultipart
      
      
      from_addr = '18392136027@163.com'
      to_addr = '1786614260@qq.com'
      smtp_server = 'smtp.163.com'
      smtp_port = 25
      subject_msg = 'subject'
     
      mul_msg = MIMEMultipart()
      mul_msg['From'] = from_addr
      mul_msg['To'] = to_addr
      mul_msg['Subject'] = subject_msg
     
      msg = MIMEText('\n\rimportant message\n\r', 'plain', 'utf-8')
      mul_msg.attach(msg)
     
      att1 = MIMEText(open('program.txt','rb').read(), 'base64', 'utf-8')
      att1['Content-Type'] = 'application/octet-stream'
      att1["Content-Disposition"] = 'attachment;filename="program.txt"'
      mul_msg.attach(att1)
     
      smtp = SMTP(smtp_server, smtp_port)
      smtp.login(from_addr, 'youpass')
      smtp.set_debuglevel(1)
      smtp.sendmail(from_addr, to_addr, mul_msg.as_string())
      smtp.close()
     

     
     

     使用第三方開源庫yagmail發(fā)送電子郵件

     import yagmail
     yag = yagmail.SMTP(user='youQQ@qq.com', password='you pass', host='smtp.qq.com', port=25)
     contents = ['import message','program.txt']
     yag.send(to='dest', subject='subject', contents=contents)
     

     使用pop3協(xié)議用網(wǎng)易郵箱發(fā)送郵件時钠怯，容易被網(wǎng)易識別為垃圾郵件佳魔，可以使用qq郵箱