编写非阻塞的TCP连接程序

下面代码使用了select模块来管理多个 socket 连接，server_socket.setblocking(0)将服务器 socket 设置为非阻塞模式 ，在接收数据时，若没有数据可读，会捕获EAGAIN或EWOULDBLOCK错误并继续循环。

import socket
import selectdef non_blocking_tcp_server():server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)server_address = ('localhost', 10000)server_socket.bind(server_address)server_socket.listen(1)# 设置为非阻塞模式server_socket.setblocking(0)inputs = [server_socket]print("Server is listening on {}:{}".format(*server_address))while inputs:readable, writable, exceptional = select.select(inputs, [], inputs)for s in readable:if s is server_socket:connection, client_address = s.accept()print(f"New connection from {client_address}")connection.setblocking(0)inputs.append(connection)else:try:data = s.recv(1024)if data:print(f"Received from {s.getpeername()}: {data.decode()}")s.sendall(b"Hello, client!")else:print(f"Closing connection from {s.getpeername()}")inputs.remove(s)s.close()except socket.error as e:if e.errno in (socket.errno.EAGAIN, socket.errno.EWOULDBLOCK):continueelse:print(f"Error: {e}")inputs.remove(s)s.close()for s in exceptional:print(f"Handling exceptional condition for {s.getpeername()}")inputs.remove(s)s.close()if __name__ == "__main__":non_blocking_tcp_server()

编写UDP的socket程序

UDP 是无连接的传输协议，相比 TCP 更简单。我将重新编写代码，展示如何使用 Python 实现 UDP 发送和接收报文，重点在于socket模块中 UDP 相关的函数调用。

import socketdef udp_send_receive():# 创建UDP socketudp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)# 绑定地址和端口server_address = ('localhost', 10001)udp_socket.bind(server_address)# 发送数据message = "Hello, UDP!"target_address = ('localhost', 10002)udp_socket.sendto(message.encode(), target_address)while True:try:# 接收数据data, client_address = udp_socket.recvfrom(1024)print(f"Received from {client_address}: {data.decode()}")except socket.error as e:print(f"Error: {e}")if __name__ == "__main__":udp_send_receive()

上述代码中，先创建 UDP socket 并绑定地址端口，然后向目标地址发送数据，接着进入循环持续接收数据。

这里说明一下UDP的调试，类型选择udp,端口是刚才代码中绑定的端口。

创建连接

发送数据

点创建，然后发送随便的内容

显示收到了数据

多线程管理udp

下面这个例子，是把收发放在不同的线程中进行运行。提高程序的并发性，我将引入threading模块来创建线程。

import socket
import threadingdef udp_send(udp_socket, target_address):message = "Hello, UDP!"while True:try:udp_socket.sendto(message.encode(), target_address)# 为了避免发送过于频繁，这里添加一个小的时间间隔，单位为秒import timetime.sleep(1)except socket.error as e:print(f"Send Error: {e}")def udp_receive(udp_socket):while True:try:data, client_address = udp_socket.recvfrom(1024)print(f"Received from {client_address}: {data.decode()}")except socket.error as e:print(f"Receive Error: {e}")def main():# 创建UDP socketudp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)# 绑定地址和端口server_address = ('localhost', 10001)udp_socket.bind(server_address)target_address = ('localhost', 10002)send_thread = threading.Thread(target=udp_send, args=(udp_socket, target_address))receive_thread = threading.Thread(target=udp_receive, args=(udp_socket,))send_thread.start()receive_thread.start()send_thread.join()receive_thread.join()if __name__ == "__main__":main()