我必须从 FTP 服务器下载一些文件。似乎足够平淡无奇。但是，此服务器的行为方式是，如果文件非常大，则连接会在表面上完成下载时挂起。
如何在 python 中使用 ftplib 优雅地处理这个问题？
示例 python 代码:
from ftplib import FTP
...
ftp = FTP(host)
ftp.login(login, passwd)
files=ftp.nlst()
ftp.set_debuglevel(2)
for fname in files:
ret_status = ftp.retrbinary('RETR ' + fname, open(fname, 'wb').write)
上面的调试输出:
*cmd* 'TYPE I'
*put* 'TYPE I\r\n'
*get* '200 Type set to I.\r\n'
*resp* '200 Type set to I.'
*cmd* 'PASV'
*put* 'PASV\r\n'
*get* '227 Entering Passive Mode (0,0,0,0,10,52).\r\n'
*resp* '227 Entering Passive Mode (0,0,0,0,10,52).'
*cmd* 'RETR some_file'
*put* 'RETR some_file\r\n'
*get* '125 Data connection already open; Transfer starting.\r\n'
*resp* '125 Data connection already open; Transfer starting.'
[just sits there indefinitely]
这是我尝试使用 curl -v 进行相同下载时的样子:
* About to connect() to some_server port 21 (#0)
* Trying some_ip... connected
* Connected to some_server (some_ip) port 21 (#0)
< 220 Microsoft FTP Service
> USER some_user
< 331 Password required for some_user.
> PASS some_password
< 230 User some_user logged in.
> PWD
< 257 "/some_dir" is current directory.
* Entry path is '/some_dir'
> EPSV
* Connect data stream passively
< 500 'EPSV': command not understood
* disabling EPSV usage
> PASV
< 227 Entering Passive Mode (0,0,0,0,11,116).
* Trying some_ip... connected
* Connecting to some_ip (some_ip) port 2932
> TYPE I
< 200 Type set to I.
> SIZE some_file
< 213 229376897
> RETR some_file
< 125 Data connection already open; Transfer starting.
* Maxdownload = -1
* Getting file with size: 229376897
{ [data not shown]
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 218M 100 218M 0 0 182k 0 0:20:28 0:20:28 --:--:-- 0* FTP response timeout
* control connection looks dead
100 218M 100 218M 0 0 182k 0 0:20:29 0:20:29 --:--:-- 0* Connection #0 to host some_server left intact
curl: (28) FTP response timeout
* Closing connection #0
wget 的输出也很有趣，它注意到连接已断开，然后尝试重新下载文件，这只会确认它已经完成:
--2009-07-09 11:32:23-- ftp://some_server/some_file
=> `some_file'
Resolving some_server... 0.0.0.0
Connecting to some_server|0.0.0.0|:21... connected.
Logging in as some_user ... Logged in!
==> SYST ... done. ==> PWD ... done.
==> TYPE I ... done. ==> CWD not needed.
==> SIZE some_file ... 229376897
==> PASV ... done. ==> RETR some_file ... done.
Length: 229376897 (219M)
100%[==========================================================>] 229,376,897 387K/s in 18m 54s
2009-07-09 11:51:17 (198 KB/s) - Control connection closed.
Retrying.
--2009-07-09 12:06:18-- ftp://some_server/some_file
(try: 2) => `some_file'
Connecting to some_server|0.0.0.0|:21... connected.
Logging in as some_user ... Logged in!
==> SYST ... done. ==> PWD ... done.
==> TYPE I ... done. ==> CWD not needed.
==> SIZE some_file ... 229376897
==> PASV ... done. ==> REST 229376897 ... done.
==> RETR some_file ... done.
Length: 229376897 (219M), 0 (0) remaining
100%[+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++] 229,376,897 --.-K/s in 0s
2009-07-09 12:06:18 (0.00 B/s) - `some_file' saved [229376897]
请您参考如下方法:
我认为一些调试可能会有用。你能把下面的类折叠到你的代码中吗？ (我自己没有这样做，因为我知道这个版本有效，并且不想冒犯错误的风险。你应该能够将类放在文件的顶部并用什么替换循环体我在#LOOP BODY 之后写过)
class CounterFile():
def __init__(self, file, maxsize):
self.file = file
self.count = 0
self.maxsize = maxsize
def write(self, bytes):
self.count += len(bytes)
print "total %d bytes / %d"%(self.count, self.maxsize)
if self.count == self.maxsize:
print " Should be complete"
self.file.write(bytes)
from ftplib import FTP
ftp = FTP('ftp.gimp.org')
ftp.login('ftp', 'thouis@gmail.com')
ftp.set_debuglevel(2)
ftp.cwd('/pub/gimp/v2.6/')
fname = 'gimp-2.6.2.tar.bz2'
# LOOP BODY
sz = ftp.size(fname)
if sz is None:
print "Could not get size!"
sz = 0
ret_status = ftp.retrbinary('RETR ' + fname, CounterFile(open(fname, 'wb'), sz).write)
