listing27-3.py

《Beginning Python--From Novice to Professional》 的源码

from xmlrpclib import ServerProxy, Fault
from cmd import Cmd
from random import choice
from string import lowercase
from server import Node, UNHANDLED
from threading import Thread
from time import sleep
import sys

HEAD_START = 0.1 # Seconds
SECRET_LENGTH = 100

def randomString(length):
    """
    Returns a random string of letters with the given length.
    """
    chars = []
    letters = lowercase[:26]
    while length > 0:
        length -= 1
        chars.append(choice(letters))
    return ''.join(chars)

class Client(Cmd):
    """
    A simple text-based interface to the Node class.
    """

    prompt = '> '


    def __init__(self, url, dirname, urlfile):
        """
        Sets the url, dirname, and urlfile, and starts the Node
        Server in a separate thread.
        """
        Cmd.__init__(self)
        self.secret = randomString(SECRET_LENGTH)
        n = Node(url, dirname, self.secret)
        t = Thread(target=n._start)
        t.setDaemon(1)
        t.start()
        # Give the server a head start:
        sleep(HEAD_START)
        self.server = ServerProxy(url)
        for line in open(urlfile):
            line = line.strip()
            self.server.hello(line)

    def do_fetch(self, arg):
        "Call the fetch method of the Server."
        try:
            self.server.fetch(arg, self.secret)
        except Fault, f:
            if f.faultCode != UNHANDLED: raise
            print "Couldn't find the file", arg

    def do_exit(self, arg):
        "Exit the program."
        print
        sys.exit()

    do_EOF = do_exit # End-Of-File is synonymous with 'exit'

def main():
    urlfile, directory, url = sys.argv[1:]
    client = Client(url, directory, urlfile)
    client.cmdloop()

if __name__ == '__main__': main()