import socket
"服务器端"

server = socket.socket() # 生成连接对象
server.bind(("localhost",6000)) # 绑定要监听的端口
server.listen(5) # 开始监听（最大允许挂起的连接）
while True:
    print("\n服务器在等待...")
    conn,addr = server.accept() # 等待客户端发起建立连接，起到阻塞作用
    # conn 是客户端链接过来而在服务器端为其生成的连接实例，addr是IP地址+端口
    print("已成功连接")
    print("连接对象：{0}，地址：{1}\n".format(conn,addr))
    while True:
        try:
            data = conn.recv(1024)  # 接收数据
            # (如果客服端断开连接，此步骤将会被无限循环操作，所以一定要有检查机制)
            if data != b"000001":  # 接收到的信号不是"000001"的话就正常执行
                print("接收客户端信息：", data.decode())
                msg = input(">>输入返回客户端的数据：")
                conn.send(msg.encode(encoding="utf-8")) # 向客户端发送数据
            else:
                print("该客户已主动断开连接")
                break
        except ConnectionResetError as e:
            print("该客户机异常！已被强迫断开连接",e)
            break
        else:
            print("It's OK !")

server.close()

import socket
"通信案例客户端消息接收与发送"
client = socket.socket() # 声明socket类型，并生成socket连接对象
try:
    client.connect(("localhost",6000)) # 与服务器建立连接

    while True:
        msg = input(">>输入要向服务器发送的信息：")
        client.send(msg.encode(encoding="utf-8")) # 向服务器发送信息(只能发送bytes字节类型，不能是str字符类型)
        data = client.recv(1024) # 接收来自服务器的1024个字节
        print("接收来自服务器的数据：",data.decode()) # 打印服务器发送的数据
        chioce = input("按任意键继续，按0退出客户端")
        if chioce == "0":
            client.send(b"000001") # 发送此信号表明客户端要断开连接
            break
        client.close()
except ConnectionRefusedError as e:
    print("服务器还没开机！请静候")

import socket,os,hashlib

ser = socket.socket()
ser.bind(("localhost",5000))
ser.listen()

while True:
    try:
        print("正在等待客户端连接...")
        conn,addr = ser.accept()
        print("已连接，new conn:",addr)
        while True:
            data = conn.recv(8192)
            filename = data.decode()
            print("寻找文件",filename)
            if os.path.isfile(filename):
                conn.send(b"01")
                conn.recv(1024)
                f = open(filename,"rb")
                m = hashlib.md5()
                file_size = os.stat(filename).st_size
                conn.send(str(file_size).encode(encoding="utf-8"))
                client_ack = conn.recv(1024)  # 接收确认信息
                if client_ack == b"1":
                    print("开始发送数据")
                for line in f:
                    m.update(line)
                    conn.send(line)
                f.close()
                conn.send(m.hexdigest().encode(encoding="utf-8")) # 发送MD5值
            else:
                conn.send(b"00") #表示文件不存在
                print("该文件不存在！")
    except ConnectionResetError:
        print("该客户端已断开连接")


ser.close()
print("服务器已关闭")

import socket,hashlib


def receive1(client):
    "真正的数据接收"
    while True:
        res = b""
        res = res + client.recv(1024)
    return res

def receive(client,filename):
    "接收处理"
    m = hashlib.md5()
    rece_res_size = int(client.recv(1024).decode())  # 接收的结果长度，转成int型
    client.send(b"1")
    rece_size = 0
    res = b""
    filename = filename.decode()
    f = open(filename + ".new","wb")
    while rece_size < rece_res_size:
        if rece_res_size - rece_size >1024: # 如果不是最后一次接收数据
            size = 1024
        else: # 最后一次接收数据
            size = rece_res_size - rece_size
        a = client.recv(size) # 循环接收数据
        res = res + a
        rece_size = len(res)
        m.update(a)
        f.write(a)
        print("发送数据量:{0}，接收数据量:{1}".format(rece_res_size,rece_size))
    else:
        serves_md5 = client.recv(1024).decode()
        print("服务器MD5：",serves_md5)
        print("客户端MD5：",m.hexdigest())
        if serves_md5 == m.hexdigest():
            print("文件接收并校验完毕！")
    res.decode()
    f.close()

def main():
    client = socket.socket()
    try:
        client.connect(("localhost", 5000))
        while True:
            filename = input("请输入需要的文件名").strip().encode(encoding="utf-8")
            if len(filename) == 0:
                print("输入为空，重新输入")
                continue
            client.send(filename)
            is_file = client.recv(1024)
            if is_file == b"01":
                client.send(b"OK")
                receive(client,filename) # 调用函数接收数据，返回结果res（bytes）
            else:
                print(" {0} 文件不存在！".format(filename.decode()))

    except ConnectionRefusedError:
        print("等待服务器开机")
    client.close()

main()

import socketserver
'''
每一个客户端请求过来，都会实例化 MyTCPHandler
'''

class MyTCPHandler(socketserver.BaseRequestHandler):
    def handle(self):
        "跟客户端所有的交互都是在handle里完成的"
        while True:
            try:
                self.data = self.request.recv(1024).strip()
                print("{0} wrote:".format(self.client_address[0]))
                print(self.data)
                if not self.data:
                    print("输入为空")
                    self.request.send(bytes("输入为空", "utf-8"))
                else:
                    self.request.send(self.data.upper())
            except ConnectionResetError :
                print("客户已断开连接")
                break

if __name__ == "__main__":
    HOST, PORT = "localhost", 9999
    #server = socketserver.TCPServer((HOST, PORT), MyTCPHandler) # 实例化一对一的连接对象
    server = socketserver.ThreadingTCPServer((HOST, PORT), MyTCPHandler) # 实例化多并发的连接对象(多线程)
    server.serve_forever()

import socket

HOST, PORT = "localhost", 9999
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
while True:
    data = input("输入字符")
    try:
        sock.sendall(bytes(data + "\n", "utf-8"))

        received = str(sock.recv(1024), "utf-8")
    finally:
        print("Sent:     {0}".format(data))
        print("Received: {0}".format(received))

sock.close()