使用select()监听TCP和UDP消息

Question

我在尝试这段代码时，只能收到TCP消息：

from socket import *
from select import select

def read_tcp(s):
    while True:
        client,addr = s.accept()
        data = client.recv(8000)
        client.close()
        print "Recv TCP:'%s'" % data

def read_udp(s):
    while True:
        data,addr = s.recvfrom(8000)
        print "Recv UDP:'%s'" % data

def run():
    host = ''
    port = 8888
    size = 8000
    backlog = 5

    # create tcp socket
    tcp = socket(AF_INET, SOCK_STREAM)
    tcp.bind(('',port))
    tcp.listen(backlog)

    # create udp socket
    udp = socket(AF_INET, SOCK_DGRAM)
    udp.bind(('',port))

    input = [tcp,udp]

    while True:
        inputready,outputready,exceptready = select(input,[],[])

        for s in inputready:
            if s == tcp:
                read_tcp(s)
            elif s == udp:
                read_udp(s)
            else:
                print "unknown socket:", s

if __name__ == '__main__':
    run()

而客户端的代码是这样的：

from socket import *

def send_tcp():
    s = socket(AF_INET,SOCK_STREAM)
    s.connect(('localhost',8888))
    data="TCP "*4
    s.send(data)
    s.close()

def send_udp():
    s = socket(AF_INET,SOCK_DGRAM)
    data="UDP "*4
    s.sendto(data, ('localhost',8888))
    s.close()

if __name__ == '__main__':
    send_tcp()
    send_udp()

Answer 1

1. 去掉read_tcp()和read_udp()里的'while'循环。你只需要select()这个循环：它会根据需要多次调用read_XXX()方法。每个read_XXX()方法应该只处理一个事件。

2. 你的read_tcp()方法应该分成两部分：一部分用来接受一个socket并把它加入选择集合，另一部分用来读取已经接受的socket。相应地调整select循环。