send与sendall

官方文档对socket模块下的socket.send()和socket.sendall()解释如下：

socket.send(string[, flags]) Send data to the socket. The socket must be connected to a remote socket. The optional flags argument has the same meaning as for recv() above. Returns the number of bytes sent. Applications are responsible for checking that all data has been sent; if only some of the data was transmitted, the application needs to attempt delivery of the remaining data.

send()的返回值是发送的字节数量，这个数量值可能小于要发送的string的字节数，也就是说可能无法发送string中所有的数据。 如果有错误则会抛出异常。

socket.sendall(string[, flags])

Send data to the socket. The socket must be connected to a remote socket. The optional flags argument has the same meaning as for recv() above. Unlike send(), this method continues to send data from string until either all data has been sent or an error occurs. None is returned on success. On error, an exception is raised, and there is no way to determine how much data, if any, was successfully sent.

尝试发送string的所有数据，成功则返回None，失败则抛出异常。

故，下面两段代码是等价的：

# 1、sendall
sock.sendall('Hello world\n')

# 2、send
buffer = 'Hello world\n'
while buffer:
    bytes = sock.send(buffer)
    buffer = buffer[bytes:]

简单的socket客户端与服务端

'''# client'''
# -*- coding:utf-8 -*-
import socket

sk = socket.socket()
# 对方服务器的ip地址与端口号
sk.connect(('192.168.16.166',8004))
while 1:
    send = input('>>>:').strip()
    if not send:
        continue
    elif send.upper() == 'Q':
        # 退出前给sever端发信号 让他也关闭
        sk.send(send.encode('utf-8'))
        print('连接关闭！')
        break
    sk.send(send.encode('utf-8'))
    msg = sk.recv(1024).decode('utf-8')
    if msg.upper() == 'Q':
        print('连接关闭！')
        break
    print('服务器端数据：',msg)

sk.close()

'''# server'''
# -*- coding:utf-8 -*-
import socket

sk = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
# 在绑定前调用setsockopt让套接字允许地址重复利用
sk.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# 本机的ip地址与端口号
sk.bind(('192.168.16.79',9001))
sk.listen(100)
print('正在等待客户端发来信息......')
conn,addr = sk.accept()
while 1:
    # 客户端强制关闭时会抛出异常，所以用异常处理
    try:
        ## 通信循环
        msg = conn.recv(1024).decode('utf-8')
        if msg.upper() == 'Q':
            print('连接关闭！')
            break
        print('客户端数据：',msg)
        send = input('>>>::').strip()
        if not send:
            continue
        if send.upper() == 'Q':
            # 退出前给client端发信号，让他也关闭
            conn.send(send.encode('utf-8'))
            print('连接关闭！')
            break
        conn.send(send.encode('utf-8'))
    except ConnectionResetError:
        print('客户端强制退出程序，连接关闭！')
        break

conn.close()
sk.close()

'''
# 说明
总是client端先发送数据，而server端先接受数据的；
server端启动后总是在监听客户端的连接信息，因此server起初都是先接受数据的，
而且一开始让server端发送的话他也不知道目标在哪里。
'''

TCP模型

'''# client'''
# -*- coding:utf-8 -*-
import socket

sk_client = socket.socket()
sk_client.connect(('127.0.0.1',9000))
while 1:
    rec = sk_client.recv(1024).decode('utf-8')
    # 服务端主动断开链接
    if rec.upper() == 'Q':
        break
    print('服务器数据：%s'%rec)
    msg = input('>>>:').strip()
    #如果输入Q 直接退出 也不给server发送信息了
    if msg.upper() == 'Q':
        break
    sk_client.send(msg.encode('utf-8'))


'''# server'''    
# -*- coding:utf-8 -*-
import socket

sk_server = socket.socket()
sk_server.bind(('127.0.0.1',9000))
sk_server.listen()
print('Listening......')
while 1:
    conn,addr = sk_server.accept()
    while 1:
        msg = input('>>>').strip()
        conn.send(msg.encode('utf-8'))
        # 服务器主动跟正在通信的客户端关闭连接
        if msg.upper() == 'Q':
            break
        ret = conn.recv(1024).decode('utf-8')
        print('客户端 %s 数据：%s'%(addr,ret))
    conn.close()
# 服务器7*24小时运行，所以这里不关闭服务器

UDP模型

'''# client'''
# -*- coding:utf-8 -*-
import socket

sk_client = socket.socket(type=socket.SOCK_DGRAM)
server_addr = ('127.0.0.1',9000)

while 1:
    cout = input('>>>:').strip()
    # 即使输入q 也要发给服务器 服务器端有判断-你跟他断开了连接
    sk_client.sendto(cout.encode('utf-8'),server_addr)
    if cout.upper() == 'Q':
        break
    print('给服务器发送了信息：%s'%cout)
    msg = sk_client.recv(1024).decode('utf-8')
    if msg.upper() == 'Q':
        break
    print('从服务器端接收到数据：%s'%msg)

sk_client.close()


'''# server'''
# -*- coding:utf-8 -*-
import socket

sk_server = socket.socket(type=socket.SOCK_DGRAM)
sk_server.bind(('127.0.0.1',9000))

while 1:
    msg,c_addr = sk_server.recvfrom(1024)
    if msg.decode('utf-8').upper() == 'Q':
        ## 注意这里有一个元组的坑！
        print('客户端 %s 与你断开了连接'%(c_addr,))
        continue
    print('从客户端 %s 收到消息：%s'%(c_addr,msg.decode('utf-8')))
    cout = input('>>>:')
    sk_server.sendto(cout.encode('utf-8'),c_addr)
    if cout.upper() == 'Q':
        # ## 注意这里有一个元组的坑！
        print('已给客户端 %s 发送断开连接指令'%(c_addr,))
        continue
    print('给客户端 %s 发送了信息：%s'%(c_addr,cout))
    # 服务器不停止 所以不给他close

基于TCP的登陆—用到反射

'''# client'''
# -*- coding:utf-8 -*-
import json
import socket

count = 0
while count < 3:
    username = input('用户名：').strip()
    password = input('密 码：').strip()

    sk_client = socket.socket()
    sk_client.connect(('127.0.0.1',9005))

    dic = {
        'operate':'login',
        'username':username,
        'password':password,
    }

    # 用json变成str类型的 方便网络传输
    str_dic = json.dumps(dic)
    bytes_dic = str_dic.encode('utf-8')
    sk_client.send(bytes_dic)
    # 从服务器端接收结果
    str_dic_res = sk_client.recv(1024).decode('utf-8')
    dic_res = json.loads(str_dic_res)

    if dic_res['result']:
        print('登陆成功！')
        sk_client.close()
        break
    else:
        print('登录失败！')
    sk_client.close()



'''# server'''
# -*- coding:utf-8 -*-
import sys
import json
import socket
import hashlib

def get_md5(username,password):
    md5 = hashlib.md5(username.encode('utf-8'))
    md5.update(password.encode('utf-8'))
    return md5.hexdigest()

def login(dic):
    with open('userinfo','r')as f:
        for line in f:
            usr,pwd = line.strip().split('|')
            if usr == dic['username'] and pwd == get_md5(dic['username'],dic['password']):
                return {'operate':'login','result':True}
        else:
            return {'operate':'login','result':False}

if __name__ == '__main__':

    sk_server = socket.socket()
    sk_server.bind(('127.0.0.1',9005))
    sk_server.listen()
    print('等待客户端建立连接......')

    while 1:
        conn,addr = sk_server.accept()
        str_dic = conn.recv(1024).decode('utf-8')
        dic = json.loads(str_dic)
        # 反射
        if hasattr(sys.modules[__name__],dic['operate']):
            l = getattr(sys.modules[__name__],dic['operate'])
            ret = l(dic)
            bytes_ret = json.dumps(ret).encode('utf-8')
            conn.send(bytes_ret)
        conn.close()
    # 模拟server端不down机 下面不会执行
    sk_server.close()

基于UDP的聊天—加标识

'''# client'''
# -*- coding:utf-8 -*-
import json
import socket

sk_client = socket.socket(type=socket.SOCK_DGRAM)
server_addr = ('127.0.0.1',9112)
code = 1234
while 1:
    content = input('>>>:').strip()
    if not content:
        continue
    if content.upper() == 'Q':
        break
    dic = {'code':code,'content':content}
    str_dic = json.dumps(dic)
    sk_client.sendto(str_dic.encode('utf-8'),server_addr)

    recv = sk_client.recv(1024).decode('utf-8')
    if recv.upper() == 'Q':
        break
    print(recv)

sk_client.close()


'''# server'''
# -*- coding:utf-8 -*-
import json
import socket

sk_server = socket.socket(type=socket.SOCK_DGRAM)
sk_server.bind(('127.0.0.1',9112))

user_info = {
    1234:('whw','\033[1;32m'),
    5678:('wanghw','\033[1;31m'),
}

while 1:
    msg,addr = sk_server.recvfrom(1024)
    str_msg = msg.decode('utf-8')
    dic_msg = json.loads(str_msg)

    code = dic_msg['code']
    content = dic_msg['content']
    print('%s%s:%s'%(user_info[code][1],user_info[code][0],content))

    ret = input('>>>:').strip()
    sk_server.sendto(ret.encode('utf-8'),addr)
## 服务器不down机
sk_server.close()

粘包的解决—传大文件的实例

'''# client'''
# -*- coding:utf-8 -*-
import os
import socket
import struct
import json

sk = socket.socket()
sk.connect(('127.0.0.1',9001))

filepath = input('>>>:').strip()
filename = os.path.basename(filepath)
filesize = os.path.getsize(filepath)

dic = {'filename':filename,'filesize':filesize}
str_dic = json.dumps(dic)
bytes_dic = str_dic.encode('utf-8')
num = struct.pack('i',len(bytes_dic))

sk.send(num)
sk.send(bytes_dic)

with open(filepath,'rb')as f:
    while filesize > 2048:
        content = f.read(2048)
        sk.send(content)
        filesize -= 2048
    else:
        content = f.read(2048)
        if content:
            sk.send(content)

sk.close()



'''# server'''
# -*- coding:utf-8 -*-
import socket
import struct
import json

sk = socket.socket()
sk.bind(('127.0.0.1',9001))
sk.listen()
print('Listening...')

conn,addr = sk.accept()

bytes_num = conn.recv(4)
num = struct.unpack('i',bytes_num)[0]
str_dic = conn.recv(num).decode('utf-8')
dic = json.loads(str_dic)

filename = dic['filename']
filesize = dic['filesize']

with open(filename,'wb')as f:
    while filesize:
        content = conn.recv(2048)
        f.write(content)
        ## 收端出问题的几率大！由于有“拆包”，因此收到的不一定是2048个字节！
        ## 这里每次减去收到的content的长度！
        filesize -= len(content)
    else:
        content = conn.recv(2048)
        if content:
            f.write(content)

并发的socketserver

'''client'''
# -*- coding:utf-8 -*-
import socket

client = socket.socket()
client.connect(('127.0.0.1',9000))

while 1:
    try:
        msg = client.recv(1024).decode('utf-8')
        print(msg)
        client.send('client1'.encode('utf-8'))
    except Exception as e:
        print(e)
        break
client.close()


'''server'''
# -*- coding:utf-8 -*-
import socketserver
import  time

# 必须继承这个父类
class Myserver(socketserver.BaseRequestHandler):
    # 必须有一个叫handle的方法
    def handle(self):
        conn = self.request
        # 对于 “并发的文件上传” 这样做是互不影响的！
        for i in range(200):
            conn.send(('hello%s'%i).encode('utf-8'))
            msg = conn.recv(1024)
            print(msg)
            time.sleep(0.5)

if __name__ == '__main__':
    # 格式是固定的
    # 第一个参数是绑定的ip与端口 第二个参数是自己的类
    server_obj = socketserver.ThreadingTCPServer(('127.0.0.1',9001),Myserver)
    server_obj.serve_forever()

基于原生socket实现的登陆与大文件加密上传实例

目录结构如下

-client_files
-server_files
-client.py
-server.py
-userinfo

client端

# -*- coding:utf-8 -*-
import os
import sys
import json
import struct
import socket
import hashlib

# 进度条
def progress_bar(total_size, current_percent=0, last_percent=0):
    '''进度条功能'''
    while 1:
        received_size = yield current_percent
        current_percent = int(received_size / total_size * 100)
        if current_percent > last_percent:
            print("*" * int(current_percent / 2) + "{percent}%".format(percent=current_percent), end='\r',
                  flush=True)
            # 把本次循环的percent赋值给last
            last_percent = current_percent


# 大文件的MD5
def get_file_md5(filepath):
    filesize = os.path.getsize(filepath)
    md5 = hashlib.md5()
    with open(filepath,'rb')as f:
        while filesize > 1024:
            content = f.read(1024)
            md5.update(content)
            filesize -= 1024
        else:
            content = f.read()
            if content:
                md5.update(content)
    return md5.hexdigest()


# 先登录 登录成功后再进行文件的上传
def login(username,password,client):
    dic = {'operate':'login','username':username,'password':password}
    str_dic = json.dumps(dic)
    bytes_dic = str_dic.encode('utf-8')
    num_dic = struct.pack('i',len(bytes_dic))
    # 发送字节字典的长度及字节字典
    client.send(num_dic)
    client.send(bytes_dic)
    # 接收返回的信息 {'operate':'login','result':True}
    # 先接受字典信息
    num_ret = client.recv(4)
    num = struct.unpack('i',num_ret)[0]
    str_ret = client.recv(num).decode('utf-8')
    ret_dic = json.loads(str_ret)
    # 登录成功的话，upload还会利用资源，这里不关闭
    if ret_dic['result']:
        return True
    else:
        # 登陆失败记得关闭资源
        client.close()
        return False


def upload(client):
    print('upload...')
    filepath = input('请输入你要上传的文件路径：').strip()
    filename = os.path.basename(filepath)
    filesize = os.path.getsize(filepath)
    # 文件的MD5
    file_md5 = get_file_md5(filepath)
    # 建字典、传字典
    dic = {'filename':filename,'filesize':filesize,'file_md5':file_md5}
    str_dic = json.dumps(dic)
    bytes_dic = str_dic.encode('utf-8')
    num_dic = struct.pack('i',len(bytes_dic))
    # 发送字典信息及字典
    client.send(num_dic)
    client.send(bytes_dic)
    # 开始发送文件
    with open(filepath,'rb')as f:
        while filesize > 1024:
            content = f.read(1024)
            client.send(content)
            filesize -= 1024
        else:
            content = f.read()
            if content:
                client.send(content)
    # 最后关闭资源
    client.close()
    print('文件 %s 上传完成！'%filename)


def download(client):
    print('download...')

    filename = input('请输入你要下载的文件名：').strip()
    filepath = os.path.join('client_files',filename)
    # 文件名传给server
    client.send(filename.encode('utf-8'))
    # 从server端收结果，如果有这个文件就进行操作 {'filesize':filesize,'file_md5':file_md5}
    ret_str = client.recv(1024).decode('utf-8')
    ret_dic = json.loads(ret_str)
    if ret_dic['filesize'] and ret_dic['file_md5']:
        filesize = ret_dic['filesize']
        file_md5 = ret_dic['file_md5']

        # 进度条
        progress_generator = progress_bar(filesize)
        progress_generator.__next__()
        recv_size = 0
        total = filesize

        with open(filepath,'wb')as f:
            while  filesize > 1024:
                content = client.recv(1024)
                f.write(content)
                # 注意 每次长度是 len(content)
                # 因为接收的不一定是1024长度 可能会小于这个值
                filesize -= len(content)
                recv_size += 1024
                # 打印进度条
                progress_generator.send(recv_size)

            else:
                content = client.recv(1024)
                if content:
                    f.write(content)
                print('---文件 [%s] 接收完成！总大小 [%s]---' % (filename, total))
        client.close()
        # md5校验
        if get_file_md5(filepath) == file_md5:
            print('文件传输完成，校验后无误！')
        else:
            print('请注意！文件略有损坏哦~')

    else:
        print('服务端没有这个文件！')
        client.close()




if __name__ == '__main__':
    # 操作的字典 反射用
    operate_dic = {
        '1':['upload','上传文件到服务器'],
        '2':['download','从服务器端下载文件'],
    }

    username = input('用户名：').strip()
    password = input('密码：').strip()
    # 创建socket的资源
    sk_client = socket.socket()
    sk_client.connect(('127.0.0.1', 9000))

    res = login(username,password,sk_client)
    # 如果登录成功就开始选择上传还是下载
    if res:
        print('登陆成功！请选择你要进行的操作：')
        for i in operate_dic:
            print(i,':',operate_dic[i][1])
        choice = input('请选择操作的序号：').strip()
        # 反射
        if hasattr(sys.modules[__name__],operate_dic[choice][0]):
            # 注意，把client端要进行的操作发给server端，让他做好对应的操作！
            operate_str = operate_dic[choice][0]
            sk_client.send(operate_str.encode('utf-8'))
            # 然后client端进行对应的操作
            method = getattr(sys.modules[__name__],operate_dic[choice][0])
            method(sk_client)
        else:
            print('请输入正确的操作序号！')
    else:
        print('登陆失败！')

server端

# -*- coding:utf-8 -*-
import os
import sys
import json
import struct
import socket
import hashlib

def get_md5(username,password):
    md5 = hashlib.md5(username.encode('utf-8'))
    md5.update(password.encode('utf-8'))
    return md5.hexdigest()


# 大文件的MD5
def get_file_md5(filepath):
    filesize = os.path.getsize(filepath)
    md5 = hashlib.md5()
    with open(filepath,'rb')as f:
        while filesize > 1024:
            content = f.read(1024)
            md5.update(content)
            filesize -= 1024
        else:
            content = f.read()
            if content:
                md5.update(content)
    return md5.hexdigest()


def login(username,password):
    ## whw  123
    with open('userinfo','r',encoding='utf-8')as f:
        for line in f:
            user,pwd = line.strip().split('|')
            if user == username and pwd == get_md5(username,password):
                return {'operate':'login','result':True}
            else:
                return {'operate':'login','result':False}


def upload(conn):
    print('upload...')
    # 接收字典的长度与字典
    num_dic = conn.recv(4)
    num = struct.unpack('i',num_dic)[0]
    str_dic = conn.recv(num).decode('utf-8')
    dic = json.loads(str_dic)
    # 得到相关信息
    filename = dic['filename']
    filesize = dic['filesize']
    # 开始接收文件
    with open(filename,'wb')as f:
        while filesize > 1024:
            content = conn.recv(1024)
            f.write(content)
            # 注意每次收到不一定是1024！
            # 因此这里用content的长度做减法！
            filesize -= len(content)
        else:
            content = conn.recv(1024)
            if content:
                f.write(content)
    # 进行文件的MD5校验
    file_md5 = get_file_md5(filename)
    if file_md5 == dic['file_md5']:
        print('文件 %s 上传成功！校验无误!' % filename)
    # 最后记得关闭资源
    conn.close()


def download(conn):
    print('download...')
    # 从client端接收文件名
    filename = conn.recv(1024).decode('utf-8')
    file_path = os.path.join('server_files', filename)
    filesize = None
    if filename in os.listdir('server_files'):
        filesize = os.path.getsize(file_path)
        file_md5 = get_file_md5(file_path)
        dic = {'filesize': filesize, 'file_md5': file_md5}
    else:
        dic = {'filesize':None,'file_md5':None}
    # 把这个字典传给client，让它确认是否可以进行下载了
    str_dic = json.dumps(dic)
    conn.send(str_dic.encode('utf-8'))
    # 如果有这个文件表示可以下载了，server开始给他传
    if dic['filesize'] and dic['file_md5']:
        with open(file_path,'rb')as f:
            while filesize > 1024:
                content = f.read(1024)
                conn.send(content)
            else:
                content = f.read()
                if content:
                    conn.send(content)
        # 最后记得关闭conn
        conn.close()
    else:
        print('客户端 %s 试图下载文件失败'%(addr,))
        conn.close()


if __name__ == '__main__':
    server = socket.socket()
    server.bind(('127.0.0.1',9000))
    server.listen()
    print('listening......')
    while 1:
        conn,addr = server.accept()
        # 先收字典长度再收字典
        bytes_num = conn.recv(4)
        num = struct.unpack('i',bytes_num)[0]
        str_dic = conn.recv(num).decode('utf-8')
        dic = json.loads(str_dic)
        ret = login(dic['username'],dic['password'])
        # 返回给client
        str_ret = json.dumps(ret)
        bytes_ret = str_ret.encode('utf-8')
        num_ret = struct.pack('i',len(bytes_ret))
        # 先发字节字典的长度再发字节字典
        conn.send(num_ret)
        conn.send(bytes_ret)

        # 登陆成功upload与download还会用到conn，先不关闭
        if ret['result']:
            #从client端收一下 到底是进行什么操作吧
            str_operate = conn.recv(1024).decode('utf-8')
            # 用反射获取
            if hasattr(sys.modules[__name__],str_operate):
                method = getattr(sys.modules[__name__],str_operate)
                method(conn)
        else:
            # 注意这里是单个元组的传参！
            print('客户端 %s 登录失败'%(addr,))
            # 登录失败的话断开当前连接
            conn.close()

基于socketserver的并发的文件上传实例

'''client'''
# -*- coding:utf-8 -*-
import os
import json
import struct
import socket


filepath = input('请输入文件路径：').strip()
filename = os.path.basename(filepath)
filesize = os.path.getsize(filepath)
# 构建字典 并 求出传输所需的参数
dic = {'filename':filename,'filesize':filesize}
str_dic = json.dumps(dic)
bytes_dic = str_dic.encode('utf-8')
num_dic = struct.pack('i',len(bytes_dic))
# 准备并传输
sk_client = socket.socket()
sk_client.connect(('127.0.0.1',9000))
sk_client.send(num_dic)
sk_client.send(bytes_dic)
# 开始上传文件
with open(filepath,'rb')as f:
    while filesize > 1024:
        content = f.read(1024)
        sk_client.send(content)
        filesize -= 1024
    else:
        content = f.read()
        if content:
            sk_client.send(content)
# 关闭资源
sk_client.close()


'''server'''
# -*- coding:utf-8 -*-
import json
import struct
import socketserver

class MyServer(socketserver.BaseRequestHandler):
    def handle(self):
        while 1:
            conn = self.request
            # 接收带信息的字典 先接收长度
            num_dic = conn.recv(4)
            # 注意取到的是元组 需要取索引为0的元素才能拿到数字！
            num = struct.unpack('i',num_dic)[0]
            str_dic = conn.recv(num).decode('utf-8')
            dic = json.loads(str_dic)
            filename = dic['filename']
            filesize = dic['filesize']
            # 开始接收数据
            with open(filename,'wb')as f:
                while filesize > 1024:
                    content = conn.recv(1024)
                    f.write(content)
                    # 注意 收到的不一定是1024长度 因此这里每次减content的长度
                    filesize -= len(content)
                else:
                    # 每次收到不一定是1024 因此这里每次减content的长度
                    content = conn.recv(1024)
                    if content:
                        f.write(content)
            conn.close()

if __name__ == '__main__':
    ser_obj = socketserver.ThreadingTCPServer(('127.0.0.1',9000),MyServer)
    ser_obj.serve_forever()

上传+下载+生成器

目录结构

-download
-upload
-client.py
-server.py
userinfo

client

# -*- coding:utf-8 -*-
import os
import json
import socket
import struct


download_path = r'E:\practice\old_boy_all_day\all_days\day31-下载与校验\download'

username = input('username:').strip()
password = input('password:').strip()
dic = {'username':username,'password':password,'opt':'login'}

str_dic = json.dumps(dic)
bytes_dic = str_dic.encode('utf-8')
num_dic = struct.pack('i',len(bytes_dic))

sk = socket.socket()
sk.connect(('127.0.0.1',9001))

sk.send(num_dic)
sk.send(bytes_dic)

str_ret = sk.recv(1024).decode('utf-8')
ret_dic = json.loads(str_ret)
if ret_dic['flag']:
    print('登陆成功！')
else:
    print('登陆失败！')

#选择 上传 还是 下载

#默认参数！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
# 用自定义协议传字典写一个函数 ############################################################
def pro_send(sk,dic,pro=True):
    str_dic = json.dumps(dic)
    bytes_dic = str_dic.encode('utf-8')
    if pro:
        num_dic = struct.pack('i', len(bytes_dic))
        sk.send(num_dic)
    sk.send(bytes_dic)




def upload(sk):
    filepath = input('文件路径：').strip()
    if os.path.isfile(filepath):
        filename = os.path.basename(filepath)
        filesize = os.path.getsize(filepath)
        dic = {'filename':filename,'filesize':filesize,'operate':'upload'}

        pro_send(sk,dic)       ##################################################################

        with open(filepath,'rb')as f:
            while filesize > 2048:
                content = f.read(2048)
                sk.send(content)
                filesize -= 2048
            else:
                content = f.read()
                if content:
                    sk.send(content)
        print('上传成功！')


def pro_recv(conn):  ######################### 根据协议接收###################################
    num_dic = conn.recv(4)
    # 注意unpack得到的是元组！！！
    num = struct.unpack('i', num_dic)[0]
    str_dic = conn.recv(num).decode('utf-8')
    dic = json.loads(str_dic)
    return dic

def download(sk):
    # 先发送要下载文件的名字
    # server回复：是否存在，文件大小
    # 根据文件大小来接收文件 收到的文件存在download文件件下
    filename = input('文件名：').strip()
    dic = {'filename': filename,  'operate': 'download'}
    # 不用自定义协议
    # 默认参数！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
    pro_send(sk,dic)

    ret = pro_recv(sk)   #   dic = {'filesize':filesize,'exist':True}
    if ret['exist']:
        filepath = os.path.join('download',filename)
        with open(filepath, 'wb')as f:
            while ret['filesize']:
                content = sk.recv(2048)
                f.write(content)
                ret['filesize'] -= len(content)
            else:
                content = sk.recv(2048)
                if content:
                    f.write(content)
        print('下载成功！')

    else:
        print('文件不存在！')



operate = [('上传',upload),('下载',download)]

for k,v in enumerate(operate,1):
    print(k,v[0])

num = input('请输入您要进行的操作：').strip()

opt = operate[int(num)-1][1]
opt(sk)

server

# -*- coding:utf-8 -*-
import os
import sys
import json
import struct
import socket
import hashlib


uploadpath = r'E:\practice\old_boy_all_day\all_days\day31-下载与校验\upload'


#默认参数！！！！！！！！
# 位自定义协议传字典写一个函数 ########
def pro_send(sk,dic,pro=True):
    str_dic = json.dumps(dic)
    bytes_dic = str_dic.encode('utf-8')
    if pro:
        num_dic = struct.pack('i', len(bytes_dic))
        sk.send(num_dic)
    sk.send(bytes_dic)


def pro_recv(conn):  ####### 根据协议接收
    num_dic = conn.recv(4)
    # 注意unpack得到的是元组！！！
    num = struct.unpack('i', num_dic)[0]
    str_dic = conn.recv(num).decode('utf-8')
    dic = json.loads(str_dic)
    return dic


def get_md5(username,password):
    md5 = hashlib.md5(username.encode('utf-8'))
    md5.update(password.encode('utf-8'))
    return md5.hexdigest()

def login(conn):
    num_dic = conn.recv(4)
    # 注意unpack得到的是元组！！！
    num = struct.unpack('i', num_dic)[0]
    str_dic = conn.recv(num).decode('utf-8')
    dic = json.loads(str_dic)
    username = dic['username']
    password = dic['password']

    with open('userinfo', 'r', encoding='utf-8')as f:
        for line in f:
            usr, pwd = line.strip().split('|')
            if usr == username and pwd == get_md5(username, password):
                return {'opt':'login','flag':True}
            else:
                return {'opt': 'login', 'flag': False}

def upload(conn,dic):
    filepath = os.path.join('upload',dic['filename'])

    with open(filepath,'wb')as f:
        while dic['filesize']:
            content = conn.recv(2048)
            f.write(content)
            dic['filesize'] -= len(content)
        else:
            content = conn.recv(2048)
            if content:
                f.write(content)


def download(conn,dic):
    path = os.path.join(uploadpath,dic['filename'])
    if os.path.isfile(path):
        filesize = os.path.getsize(path)
        dic = {'filesize':filesize,'exist':True}
        # 文件存在
        # 先发字典 再发文件
        pro_send(conn,dic)

        with open(path,'rb')as f:
            while filesize > 2048:
                content = f.read(2048)
                conn.send(content)
                filesize -= 2048
            else:
                content = f.read()
                if content:
                    conn.send(content)
    else:
        # 文件不存在
        # 先发字典 再结束
        dic = {'filesize': None, 'exist': True}
        pro_send(conn, dic)
        conn.close()



if __name__ == '__main__':


    sk = socket.socket()
    sk.bind(('127.0.0.1',9001))
    sk.listen()
    print('listening......')

    conn,addr = sk.accept()

    ret = login(conn)

    # 可以不自定义协议
    ret_str = json.dumps(ret)
    conn.send(ret_str.encode('utf-8'))

    if ret['flag']:
        # 登陆成功
        dic = pro_recv(conn)   #################  {'filename':filename,'filesize':filesize,'operate':'upload'} ###############################

        if hasattr(sys.modules[__name__],dic['operate']):
            method = getattr(sys.modules[__name__],dic['operate'])
            method(conn,dic)

    else:
        conn.close()

自己实现的一个单进程的FTP服务器

https://github.com/Wanghongw/FTP