使用Python生成url短链接的方法

#引入哈希库
import hashlib 
    
def get_md5(s): 
  s = s.encode('utf8') if isinstance(s, unicode) else s 
  m = hashlib.md5() 
  m.update(s) 
  return m.hexdigest() 
    
code_map = ( 
      'a' , 'b' , 'c' , 'd' , 'e' , 'f' , 'g' , 'h' , 
      'i' , 'j' , 'k' , 'l' , 'm' , 'n' , 'o' , 'p' , 
      'q' , 'r' , 's' , 't' , 'u' , 'v' , 'w' , 'x' , 
      'y' , 'z' , '0' , '1' , '2' , '3' , '4' , '5' , 
      '6' , '7' , '8' , '9' , 'A' , 'B' , 'C' , 'D' , 
      'E' , 'F' , 'G' , 'H' , 'I' , 'J' , 'K' , 'L' , 
      'M' , 'N' , 'O' , 'P' , 'Q' , 'R' , 'S' , 'T' , 
      'U' , 'V' , 'W' , 'X' , 'Y' , 'Z'
      ) 
    
    
def get_hash_key(long_url): 
  hkeys = [] 
  hex = get_md5(long_url) 
  for i in xrange(0, 4): 
    n = int(hex[i*8:(i+1)*8], 16) 
    v = [] 
    e = 0
    for j in xrange(0, 5): 
      x = 0x0000003D & n 
      e |= ((0x00000002 & n ) >> 1) << j 
      v.insert(0, code_map[x]) 
      n = n >> 6
    e |= n << 5
    v.insert(0, code_map[e & 0x0000003D]) 
    hkeys.append(''.join(v)) 
  return hkeys 
    
if __name__ == '__main__': 
  print get_hash_key('http://www.pythontab.com')