python【系列教程】之网络编程

一、网络编程的基础知识

二、python 的基本网络支持

多线程下载文件工具类DownUtil

from urllib.request import *
import threading


class DownUtil:
    def __init__(self, path, target_file, thread_num):
        # 定义资源下载的路径
        self.path = path
        # 定义需要使用多少个线程下载资源
        self.thread_num = thread_num
        # 指定所下载的文件的保存位置
        self.target_file = target_file
        # 初始化threads数组
        self.threads = []

    def download(self):
        # 创建request对象
        req = Request(url=self.path, method='GET')
        # 添加请求头
        req.add_header('Accept', '*/*')
        req.add_header('Charset', 'UTF-8')
        req.add_header('Connection', 'Keep-Alive')
        # 打开要下载的资源
        f = urlopen(req)
        self.file_size = int(dict(f.headers).get('Content-Length', 0))
        f.close()
        # 计算每个线程要下载的资源大小
        current_part_size = self.file_size // self.thread_num + 1
        for i in range(self.thread_num):
            # 计算每个线程下载的开始位置
            start_pos = i * current_part_size
            # 每个线程使用一个wb模式打开的文件进行下载
            t = open(self.target_file, 'wb')
            # 定义该线程的下载位置
            t.seek(start_pos, 0)
            # 创建下载线程
            td = DownThread(self.path, start_pos, current_part_size, t)
            self.threads.append(td)
            # 启动线程
            td.start()

    # 获取下载完成的百分比
    def get_complete_rate(self):
        # 统计多个线程已经下载的资源总大小
        sum_size = 0
        for i in range(self.thread_num):
            sum_size += self.threads[i].length
        return sum_size / self.file_size


class DownThread(threading.Thread):
    def __init__(self, path, start_pos, current_part_size, current_part):
        super().__init__()
        self.path = path
        # 当前线程的下载位置
        self.start_pos = start_pos
        # 定义当前线程负责下载的文件大小
        self.current_part_size = current_part_size
        # 当前线程需要下载的文件块
        self.current_part = current_part
        # 定义当前线程已下载的字节数
        self.length = 0

    def run(self):
        # 创建Request对象
        req = Request(url=self.path, method='GET')
        # 添加请求头
        req.add_header('Accept', '*/*')
        req.add_header('Charset', 'UTF-8')
        req.add_header('Connection', 'Keep-Alive')
        # 打开要下载的资源
        f = urlopen(req)
        # 跳过self.start_pos个字节，表明该线程只下载自己负责的那部分内容
        for i in range(self.start_pos):
            f.read(1)
        while self.length < self.current_part_size:
            data = f.read(1024)
            if data is None or len(data) <= 0:
                break
            self.current_part.write(data)
            # 累计该线程下载的资源总大小
            self.length += len(data)
        self.current_part.close()
        f.close()

d = DownUtil('https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1569583834625&di=9a307758f95e32c324e36d00a9cdd59b&imgtype=0&src=http%3A%2F%2Fb.zol-img.com.cn%2Fsoft%2F6%2F571%2FcepyVKtIjudo6.jpg','./1.jpg',5)

d.download()

def show_process():
    print('已完成：%.2f'% d.get_complete_rate())
    global t
    if d.get_complete_rate()<1:
        t = threading.Timer(0.1,show_process)
        t.start()
t = threading.Timer(0.1,show_process)
t.start()

from urllib.request import *
import http.cookiejar, urllib.parse

cookie_jar = http.cookiejar.MozillaCookieJar('a.txt')
cookie_processor = HTTPCookieProcessor(cookie_jar)
opener = build_opener(cookie_processor)
# 定义一个模拟chrome浏览器的User-Agent
user_agent = r'Mozilla/5.0(Windows NT 6.1; wow64) AppleWebKit/537.36' \
             r'(KHTML,like Gecko) Chrome/56.0.2924.87 Safari/537.36'

# 定义请求头
headers = {'User-Agent': user_agent, 'Connection': 'keep-alive'}

# 下面代码发送登陆的post请求
# 定义登陆系统的请求参数
params = {'name': 'crazyit.org', 'pass': 'leegang'}
postdata = urllib.parse.urlencode(params).encode()
# 创建向登录页面发送的post请求的request
request = Request('http://localhost:8888/test/join.jsp', data=postdata,headers=headers)
response = opener.open(request)
print(response.read().decode('utf-8'))
# 将cookie信息写入文件
cookie_jar.save(ignore_discard=True, ignore_expires=True)
# 下面代码发送访问被保护资源的get请求
request = Request('http://localhost:8888/test/secret.jsp',headers=headers)
response = opener.open(request)
print(response.read().decode('utf-8'))

三、基于tcp协议的网络编程

# 导入socket模块
import socket

# 创建socket对象
s = socket.socket()
# 连接远程服务器
s.connect(('localhost', 30000))
print(s.recv(1024).decode('utf-8'))
s.close()

socket 通信服务端代码：

# 导入socket模块
import socket

# 创建socket对象
s = socket.socket()
# 将socket绑定到本机IP和端口
s.bind(('localhost', 30000))
# 服务器端开始监听来自客户端的连接
s.listen()

while True:
    # 每当接收到客户端的socket请求时，该方法就返回对应的socket和远程地址
    c, addr = s.accept()
    print(c)
    print('连接地址', addr)
    c.send('您好！您收到了服务器的新年祝福'.encode('utf-8'))
    # 关闭连接
    c.close()

socket通信客户端代码：

# 导入socket模块
import socket

# 创建socket对象
s = socket.socket()
# 连接远程服务器
s.connect(('localhost', 30000))
print(s.recv(1024).decode('utf-8'))
s.close()

四、基于udp协议的网络编程

五、电子邮件支持

import smtplib
from email.message import EmailMessage

# 定义smtp服务器地址
smtp_server = 'smtp.qq.com'
# 定义发件人地址
from_addr = '[email protected]'
# 定义登录邮箱的密码
password = 'plrcqrfgdajybhah'
# 定义收件人地址
to_addr = '[email protected]'
# 创建smtp连接
conn = smtplib.SMTP(smtp_server)
smtplib.SMTP_SSL(smtp_server, 465)
conn.set_debuglevel(1)
conn.login(from_addr, password)
msg = EmailMessage()
msg.set_content('您好，这是一封来自python的邮件', 'plain', 'utf-8')
conn.sendmail(from_addr, [to_addr], msg.as_string())
conn.quit()

发送html邮件

import smtplib
from email.message import EmailMessage

# 定义smtp服务器地址
smtp_server = 'smtp.qq.com'
# 定义发件人地址
from_addr = '[email protected]'
# 定义登录邮箱的密码
password = 'plrcqrfgdajybhah'
# 定义收件人地址
to_addr = '[email protected]'
# 创建smtp连接
conn = smtplib.SMTP(smtp_server)
smtplib.SMTP_SSL(smtp_server, 465)
conn.set_debuglevel(1)
conn.login(from_addr, password)
msg = EmailMessage()
msg.set_content('<h1>您好，这是一封来自python的邮件</h1>', 'html', 'utf-8')
msg['subject'] = '<h1>一封html邮件</h1>'
msg['from'] = '李刚<%s>' % from_addr
msg['to'] = '新用户<%s>' % to_addr
conn.sendmail(from_addr, [to_addr], msg.as_string())
conn.quit()