Python+MongDB实现短链接，pythonmongdb实现,实现任意数制变换（通过列

Python+MongDB实现短链接，pythonmongdb实现,实现任意数制变换（通过列

实现任意数制变换（通过列表及字典的方法）一种短网址实现方法（将MongoDB的id转化成短网址）

rebase摘自ActiveState CodeRecipes: rebase -- convert a number to/from any base in range(-256,257) 其实通过any2any的方法使用更普遍，但我是先看到rebase才写的any2any。还有一点值得注意，实例中，如果你把lis36的顺序random一下并将状态记录下来。这样可能更符合你的随机要求。

rebase.py

import stringdef rebase(i, frombase=None, tobase=None, fromalphabet=None, toalphabet=None, resize=1, too_big=40000, debug=False):    ''' if frombase is not specified, it is guessed from the type and/or char in i with highest ord.        tobase defaults to [10, 2][frombase == 10].        the alphabets are map(chr, range(256)) if its base is between 62 and 255;        otherwise, string.digits+string.letters.        always returns a string which is also valid input.        valid bases are ints in range(-256, 257).        alphabets must be subscriptable, and can only contain str's.        invalid tobases are replied with 'why?'; rebase('why?') == '217648673'.        returned string is zfilled to the next largest multiple of resize    '''    if frombase == None:        if isinstance(i, (int, long)):            frombase = 10        elif isinstance(i, str):            a = str(i)            if any([(chr(x) in a) for x in range(ord('0')) + range(58, 65) + range(91, 97) + range(123, 256)]):                frombase = max(map(ord, a)) + 1            else:                frombase = max(map((string.digits + string.letters).index, a)) + 1    if tobase == None:        tobase = [10, 2][frombase == 10]    # got bases, ensuring that everything is an int    tobase = int(tobase)    frombase = int(frombase)    abstobase = abs(tobase)    absfrombase = abs(frombase)    if absfrombase in [0, 1]:        i = len(str(i))    elif 2 <= frombase <= 36:        # may be difficult to translate to C        i = int(str(i), frombase)    else:        i = str(i)        n = 0        if fromalphabet == None:            if 62 <= absfrombase <= 256:                fromalphabet = map(chr, range(256))            else:                fromalphabet = string.digits + string.letters        fromalphabet = fromalphabet[:absfrombase]        for j in range(len(i)):            n += (frombase ** j) * fromalphabet.index(i[-1-j])        i = n    # got ints, converting to tobase    if debug: print 'converting %d from base %d to %d' % (i, frombase, tobase)    if abstobase in [0, 1]:        return '0' * ((i > 0) and int(i) or 0)    elif abstobase > 256:        return 'why?'    # if execution gets here, we might want the result to be zfilled to a multiple of resize    r = ''    if tobase == 10:        r = str(i)    else:        if i < 0:            print 'negative',            i = -i        if toalphabet is None:            if 62 <= abstobase <= 256:                toalphabet = map(chr, range(abstobase))            else:                toalphabet = (string.digits + string.letters)[:abstobase]        if tobase < 0:            i = -i        j = 0        while i != 0:            r = toalphabet[i % tobase] + r            i /= tobase            j += 1            if j >= too_big: raise "call again; set too_big bigger"    if resize > 1:        if 62 <= abstobase <= 256:            r = toalphabet[0] * (resize - (len(r) % resize)) + r        else:            r = r.zfill(len(r) + resize - (len(r) % resize))    return r

shortURL.py

from pymongo import Connectionfrom rebase import rebasedef short_url(url, size):    '''        shorten url example    '''    ## 62 charaters    CHAR62 = list('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ')    ## mapping chr(?) to 62-base charaters    re_dic = {}    j = 0    for i in CHAR62:        re_dic.update({map(chr, range(62))[j]: i})        j += 1    # another way to get it     '''    re_dic = {'\x01': '1', '\x00': '0', '\x03': '3', '\x02': '2', '\x05': '5',     '\x04': '4', '\x07': '7', '\x06': '6', '\t': '9', '\x08': '8', '\x0b': 'b',     '\n': 'a', '\r': 'd', '\x0c': 'c', '\x0f': 'f', '\x0e': 'e', '\x11': 'h',     '\x10': 'g', '\x13': 'j', '\x12': 'i', '\x15': 'l', '\x14': 'k', '\x17': 'n',     '\x16': 'm', '\x19': 'p', '\x18': 'o', '\x1b': 'r', '\x1a': 'q', '\x1d': 't',     '\x1c': 's', '\x1f': 'v', '\x1e': 'u', '!': 'x', ' ': 'w', '#': 'z', '"': 'y',     '%': 'B', '$': 'A', "'": 'D', '&': 'C', ')': 'F', '(': 'E', '+': 'H', '*': 'G',     '-': 'J', ',': 'I', '/': 'L', '.': 'K', '1': 'N', '0': 'M', '3': 'P', '2': 'O',     '5': 'R', '4': 'Q', '7': 'T', '6': 'S', '9': 'V', '8': 'U', ';': 'X', ':': 'W',     '=': 'Z', '<': 'Y'}    '''    # for test only, connecting to mongoDB    # default host->'localhost' port->'27017'    conn = Connection()    db = conn['test']    coll = db['short_url']    _one = coll.find_one({'url': url})    # if the url already existes in the database    # return it directly    if _one:        res_final =  str(_one['tiny'])    else:        uid = coll.insert({}) # insert a empty dict and get a unique id        _id = str(uid) # mongoDB returned a 24-charater id object        ## rebase 36-base to 62-base        re_str = rebase(_id, frombase=16, tobase=62)        ## use re_dic to convert re_str to 62-base charaters        res = ''.join([re_dic[x] for x in list(re_str)])        # what you need just a slice, i.e. 6 charaters        si = 0 - int(size)        res_final = res[si:]        # find the document and update it        coll.find_and_modify(query={'_id': uid}, update={'tiny': res_final, 'url': url})    return res_final

any2any.py

## # map(chr, range(48,58)) == ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']# or [str(i) for i in range(10)]# map(chr, range(65,91)) == ['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']# map(chr, range(97,123)) == ['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']## example: 36-base to 64-base#     char36 = 'u38ki9'#     lis36 = map(chr, range(48,58)) + map(chr, range(97, 123))#     map36 = any2any_map(lis36, [str(i) for i in range(36)])#     num_lis = [int(map36[i]) for i in char36]#     num_lis.reverse()#     dec = any2dec(num_lis, 36)#     lis = [str(i) for i in dec2any(dec, 64, [])]#     lis.reverse()#     lis64 = lis36 + map(chr, range(65,91))#     map64 = any2any_map([str(i) for i in range(64)], lis64)#     out_lis = [map64[i] for i in lis]#     char64 = ''.join(out_lis) #-> '1Iszjh'##def any2any_map(from_lis, to_lis):    _dic = {}    for k,v in zip(from_lis, to_lis):        _dic.update({k: v})    return _dicdef any2dec(num_lis, base):    j = 0    _dec = 0    for n in num_lis:        _dec += n * pow(base, j)        j += 1    return _decdef dec2any(dec, base, lis=[]):    if dec > 0:        lis.append(dec%base)        dec2any(dec//base, base, lis=lis)    return lis