2017.07.08 Python网络编程之设定并获取默认的套接字超时时间

1.设定并获取默认的套接字超时时间：

# -*- coding: UTF-8 -*-
# 有时候你需要处理socket库某些属性的默认值，例如套接字超时时间
# !usr/bin/env python
# Python Network Programming Cookbook --Chapter -1
# This program is optimized for Python 2.7
# It may run on any other version with/without modifications

import socket

def test_socket_timeout():
    s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    print "默认套接字超时时间是：%s" %s.gettimeout()
    s.settimeout(100)
    print "现在套接字的超时时间是：%s" %s.gettimeout()

if __name__=='__main__':
    test_socket_timeout()

 运行程序遇到问题：No py.test runner found in selected interpreter

解决办法：没有找到py.test文件，给pycharm软件管理员权限运行，然后安装pytest包，pip install pytest

结果如下：

2.优雅的处理套接字错误：

# -*- coding: UTF-8 -*-
# 编写几个try-except代码块，每个代码块对应一种可能发生的错误
# !usr/bin/env python
# Python Network Programming Cookbook --Chapter -1
# This program is optimized for Python 2.7
# It may run on any other version with/without modifications


import socket
import sys
import argparse

def main( ):
    parser=argparse.ArgumentParser(description='socket Error Example')
    parser.add_argument('--host',action="store",dest="host",required=False)
    parser.add_argument('--port',action="store",dest="port",type=int,required=False)

    parser.add_argument('--file',action="store",dest="file",required=False)
    given_args=parser.parse_args()
    host=given_args.host
    port=given_args.port
    filename=given_args.file

    try:
        s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    except socket.error,e:
        print "发生错误当创建sock对象时:%s" %e
        sys.exit(1)


    try:
        print host,port
        s.connect((host,port))
    except socket.gaierror,e:
        print "连接服务器时地址释放发生错误:%s" %e
        sys.exit(1)
    except socket.error,e:
        print "连接发生错误：%s" %e
        sys.exit(1)


    try:
        s.sendall("GET %s HTTP/1.0

" %filename)
    except socket.error,e:
        print "发送数据时发生错误:%s" %e
        sys.exit(1)


    while 1:

        try:
            buf=s.recv(2048)
        except socket.error,e:
            print "接收数据发生错误：%s" %e
            sys.exit(1)
        if not len(buf):
            break

        sys.stdout.write(buf)


if __name__=='__main__':
    main()

 

3.修改套接字发送和接收的缓存区大小：

# -*- coding: UTF-8 -*-
# 默认的套接字缓冲区大小可能不够用，此时可以将默认的套接字缓冲区大小改成一个更合适的值
# !usr/bin/env python
# Python Network Programming Cookbook --Chapter -1
# This program is optimized for Python 2.7
# It may run on any other version with/without modifications

import socket

SEND_BUF_SIZE=4096
RECV_BUF_SIZE=4096

def modify_buf_size():
    sock=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    
    bufsize=sock.getsockopt(socket.SOL_SOCKET,socket.SO_SNDBUF)
    print "缓冲区之前的大小:%d" %bufsize

    sock.setsockopt(socket.SOL_TCP,socket.TCP_NODELAY,1)
    sock.setsockopt(
        socket.SOL_SOCKET,
        socket.SO_SNDBUF,
        SEND_BUF_SIZE
    )
    sock.setsockopt(
        socket.SOL_SOCKET,
        socket.SO_RCVBUF,
        RECV_BUF_SIZE
    )

    bufsize=sock.getsockopt(socket.SOL_SOCKET,socket.SO_SNDBUF)
    print "修改后缓冲区大小是:%d" %bufsize

if __name__=='__main__':
    modify_buf_size()

 4.把套接字改为阻塞或非阻塞模式：默认情况下，TCP套接字处于阻塞模式中，也就是说，除非完成了某项操作，否则不会把控制权交还给程序

例如：调用connect()API后，连接操作会阻止程序继续往下执行，直到连接成功为止

很多情况下，你并不想让程序一直等待服务器响应或者有异常终止操作

# -*- coding: UTF-8 -*-
# 在Python中，套接字可以被设置为阻塞模式或非阻塞模式，
# 在非阻塞模式下，调用API后，例如send()或recv()方法如果遇到问题就会抛出异常，
# 但在阻塞模型下，遇到问题并不会阻止操作
# !usr/bin/env python
# Python Network Programming Cookbook --Chapter -1
# This program is optimized for Python 2.7
# It may run on any other version with/without modifications

import socket

def test_socket_modes():
    s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    s.setblocking(1)
    s.settimeout(0.5)
    s.bind(("127.0.0.1",0))

    socket_address=s.getsockname()
    print "服务器登录socket:%s" %str(socket_address)

    while(1):
        s.listen(1)

if __name__=='__main__':
    test_socket_modes()