server端:

# ftp server端
import socket, os, time

server = socket.socket()
server.bind(("localhost", 8080))
server.listen()
while True:
    conn, addr = server.accept()
    print("連接到客戶端:", addr)
    while True:
        try:  # windows會直接報錯,需要捕獲異常
            data = conn.recv(1024)
            if not data:
                print("客戶端已斷開")
                break
        except Exception as e:
            print("客戶端已經斷開")
            break
        cmd, filename = data.decode().split()  # ex: get name.txt
        if os.path.isfile(filename):
            f = open(filename, "rb")
            # 獲取文件的字節大小
            size = os.stat(filename).st_size
            conn.send(str(size).encode())  # 發送文件大小
            conn.recv(1024)
            for line in f:   # 客戶端確認後發送文件內容
                conn.send(line)
            f.close()
            print("文件下載完成")
        conn.send("not file".encode())
server.close()

client端:

import socket

client = socket.socket()
client.connect(("localhost", 8080))
while True:
    cmd = input(">>:").strip()
    if len(cmd)==0: continue
    if cmd.startswith("get"):
        client.send(cmd.encode())  # 發送請求
        server_response = client.recv(1024)
        if server_response.decode().startswith("not"):
            print("請輸入有效文件名")
            continue
        client.send(b"ready to recv file")  # 發送確認
        file_size = int(server_response.decode())  # 獲取文件大小
        rece_size=0
        filename = cmd.split()[1]
        f = open(filename + ".new", "wb")
        while rece_size < file_size:
            if file_size - rece_size > 1024:  # 要收不止一次
                size = 1024
            else:  # 最後一次了，剩多少收多少,防止之後發送數據粘包
                size = file_size - rece_size
                print("last receive:", size)
            recv_data = client.recv(size)
            rece_size += len(recv_data)  # 累加接受數據大小
            f.write(recv_data)  # 寫入文件,即下載
        else:
            print("文件下載完成")
            f.close()
client.close()

測試案例:

主要是socket的簡單使用,主要節點都有註釋

用python socket模塊實現簡單的文件下載