使用Python下载.Jar文件

Question

I am attempting to download a file from the internet using Python along with the sys and urllib2 modules. The general idea behind the program is for the user to input the version of the file they want to download, 1_4 for example. The program then adds the user input and the "/whateverfile.jar" to the url and downloads the file. My problem arises when the program inserts the "/whateverfile.jar" instead of inserting onto the same line the program inserts the "/whateverfile.jar" onto a new line. Which causes the program to fail to download the .jar properly.

Can anyone help me with this? The code and output is below.

Code:

import sys
import urllib2

print('Type version of file you wish to download.')
print('To download 1.4 for instance type "1_4" using underscores in place of the            periods.')
W = ('http://assets.file.net/')
X = sys.stdin.readline()
Y = ('/file.jar')
Z = X+Y
V = W+X
U = V+Y
T = U.lstrip()
print(T)

def JarDownload():
  url = "T"

  file_name = url.split('/')[-1]
  u = urllib2.urlopen(url)
  f = open(file_name, 'wb')
  meta = u.info()
  file_size = int(meta.getheaders("Content-Length")[0])
  print "Downloading: %s Bytes: %s" % (file_name, file_size)

  file_size_dl = 0
  block_sz = 8192
  while True:
      buffer = u.read(block_sz)
      if not buffer:
          break

      file_size_dl += len(buffer)
      f.write(buffer)
      status = r"%10d  [%3.2f%%]" % (file_size_dl, file_size_dl * 100. / file_size)
      status = status + chr(8)*(len(status)+1)
      print status,

  f.close()

Output:

Type version of file you wish to download.
To download 1.4 for instance type "1_4" using underscores in place of the periods.
1_4
http://assets.file.net/1_4
/file.jar

I am currently not calling the JarDownload() function at all until the URL will display as a single line when printed to screen

Answer 1

When you type the input and hit Return, the sys.stdin.readline() call will append the new line symbol to the string and return it. To get the desired effect, you should strip the new line from the input before using it. This should work:

X = sys.stdin.readline().rstrip()

As a side note, you should probably give more meaningful names to your variables. Names like X, Y, Z, etc. say nothing about the variables content and make even simple operations, like your concatenations, unnecessarily hard to understand.