socket模拟服务器，客户端下载东西（ftp）

服务端（ftp_server.py）

import hashlib,socket,os

server = socket.socket()
server.bind(("localhost",9999))
server.listen()
while True:
    client,address = server.accept()
    while True:
        req_data = client.recv(1024)
        print(req_data.decode())
        if not req_data:
            print("客户端连接已断开")
            break
        if len(req_data) == 0: continue
        if os.path.isfile(req_data.decode()):
            file_size = os.stat(req_data).st_size
            print("file size:",file_size)
            client.send(str(file_size).encode('utf-8'))
            client_ack = client.recv(1024)
            f = open(req_data,'rb')
            for line in f:
                m = hashlib.md5()
                print(line)
                client.send(line)
                m.update(line)
            res = m.hexdigest()
            client.send(res.encode('utf-8'))
        else:
            client.send("无此文件")

客户端（ftp_client.py）

import socket,hashlib

client = socket.socket()
client.connect(("localhost",9999))
while True:
    cmd = input("输入文件名>>:")
    if cmd !=None or cmd != '':
        client.send(cmd.encode('utf-8'))
    file_total_size = client.recv(1024)
    print(file_total_size)
    file_total_size = int(file_total_size)
    client.send(b"ok")
    curent_size = 0
    size = 0
    m = hashlib.md5()
    f = open(cmd+"new",'wb')
    while curent_size != file_total_size:
        if file_total_size-curent_size > 1024:#不是最后一次
            size = 1024
        else:
            size = file_total_size-curent_size
        ser_info = client.recv(size)
        print(ser_info)
        f.write(ser_info)
        m.update(ser_info)
        curent_size += len(ser_info)

    else:
        print("原文件：%s，新文件：%s"%(str(file_total_size),str(curent_size)))
        ser_md5 = client.recv(1024)
        cli_md5 = m.hexdigest()
        f.close()
        print("cli_md5:%s,ser_md5:%s"%(cli_md5,ser_md5.decode()))

说明：

1.程序使用python3运行

2.明确http传输的基本概念