python编程从一个ftp传输文件到另一个ftp服务器

import ftplib, sys
ftp1 = ftplib.FTP("127.0.0.1", "book", "bookpw")
ftp1.cwd("/Dir")
ftp2 = ftplib.FTP("www.holdenweb.com", "bookuser", "bookpw")
ftp2.cwd("/public")
sock1 = ftp1.transfercmd("RETR a.zip")
sock2 = ftp2.transfercmd("STOR b.zip")
 
flen = 0                           
while 1:
    block = sock1.recv(1024)       
    if len(block) == 0:            
        break
    flen += len(block)             
    while len(block) > 0:          
        sentlen = sock2.send(block)
        block = block[sentlen:]    
         
print "Transferred", flen, "bytes"
 
sock1.close()
sock2.close()
ftp1.quit()
ftp2.quit()