文泉学堂的高清png下载修正版

搜到网上高人分享的资源，做了点简化。希望对网友有点用。

'''
python 3.6, 3.7
 
pip install httpx loguru pyjwt tqdm
 
# 文泉学堂
# 3208943 ('Python+TensorFlow机器学习实战', '248') 第1页
python fetch_png.py
 
# 第10页
python fetch_png.py 3208943 10
 
'''
 
# from typing import Union, Tuple
from pathlib import Path
from time import time
import json
import httpx
import jwt
from tqdm import trange
from loguru import logger
 
JWT_SECRET = 'g0NnWdSE8qEjdMD8a1aq12qEYphwErKctvfd3IktWHWiOBpVsgkecur38aBRPn2w'
SESS = httpx.Client()
URL = 'https://lib-nuanxin.wqxuetang.com'
SESS.get(URL)
 
 
# def gen_jwt_key(self):
def gen_jwt_key(bookid):
    ''' jwt key for bookid '''
    # url = "https://lib-nuanxin.wqxuetang.com/v1/read/k?bid=%s" % bookid
    url = f'{URL}/v1/read/k?bid={bookid}'
    # r = self.session.get(url, timeout=5)
 
    # r = SESS.get(url, timeout=5)
    # j = json.loads(r.text)
 
    try:
        resp = SESS.get(url)
        resp.raise_for_status()
    except Exception as exc:
        logger.warning(exc)
        return str(exc)
 
    try:
        jdata = resp.json()
    except Exception as exc:
        logger.warning(exc)
        jdata = {}
 
    res = jdata.get('data')
    if res is None:
        raise Exception('returned None, something is not right...')
 
    return res
 
 
# def gen_jwt_token(self, page):
def gen_jwt_token(bookid, page=1):
    ''' gen jwt token '''
    cur_time = time()
    jwtkey = gen_jwt_key(bookid)
    jwttoken = jwt.encode(
        {
            "p": page,
            "t": int(cur_time) * 1000,
            "b": str(bookid),
            "w": 1000,
            # "k": json.dumps(self.jwtkey),
            "k": json.dumps(jwtkey),
            "iat": int(cur_time),
        },
        JWT_SECRET,
        algorithm='HS256',
    ).decode('ascii')
    return jwttoken
 
 
# def bookinfo(self):
def bookinfo(bookid):
    ''' bookinfo '''
    # url = f"https://lib-nuanxin.wqxuetang.com/v1/read/initread?bid={self.bookid}"  # noqa
    url = f'{URL}/v1/read/initread?bid={bookid}'
    # r = self.session.get(url)
 
    try:
        bookid = int(bookid)
    except Exception as exc:
        logger.warning(f'error: {exc}, setting bookid to 1')
        raise
    if bookid < 1:
        # logger.warning(f' bookid {bookid} < 1, setting bookid to 1')
        # bookid = 1
        raise Exception(' bookid must be bigger than zero')
 
    req = httpx.models.Request('GET', URL)
    try:
        resp = SESS.get(url)
        resp.raise_for_status()
    except Exception as exc:
        logger.warning(exc)
        resp = httpx.Response(
            status_code=499, request=req, content=str(exc).encode()
        )
 
    try:
        jdata = resp.json()
    except Exception as exc:
        logger.warning(exc)
        jdata = {}
 
    # info = json.loads(r.text)
 
    # data = info['data']
    # return data['name'], data['canreadpages']
 
    data = jdata.get('data')
 
    if data is None:
        raise Exception(
            'returned None, something is not right...可能无此书号，也有可能是网络有问题或IP被限制……'  # noqa
        )
 
    bookinfo.jdata = jdata
 
    return data.get('name'), data.get('canreadpages')
 
 
# async def download_img(self, page, task_id):
def fetch_png(bookid, page=1):
    ''' download booid page img '''
    token = gen_jwt_token(bookid, page)
    url = f'{URL}/page/img/{bookid}/{page}?k={token}'
    headers = {
        'referer': f'{URL}/read/pdf/{bookid}',
        'user-agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.100 Safari/537.36',  # noqa
    }
 
    req = httpx.models.Request('GET', URL)
 
    count = 0
    while 1:
        try:
            resp = SESS.get(url, headers=headers)
            resp.raise_for_status()
            break
        except Exception as exc:
            logger.warning(exc)
            resp = httpx.Response(
                status_code=499, request=req, content=str(exc).encode()
            )
        count += 1
        if count > 3:
            break
    else:
        logger.warning(' We tried hard (4 times), giving up')
        raise Exception('Failed... ')
 
    fetch_png.resp = resp
 
    try:
        res = resp.content
    except Exception as exc:
        logger.warning(exc)
        return b''
 
    return res
 
 
def fetch_book(bookid, page1=1, page2=None):
    ''' fetch book with bookid page1 to page2 '''
    # '''
 
    try:
        last_page = int(bookinfo(bookid)[1])
    except Exception as exc:
        logger.error(exc)
        raise
 
    if page2 is None:
        page2 = last_page
 
    for elm in trange(page1, page2 + 1):
        # if elm > 100: break
        filename = f'{bookid}-{elm:03d}.png'
        if Path(filename).exists():
            logger.info(f'{filename} already exists, sipping....')
        else:
            logger.info(f' Fetching {filename}...')
 
            count = 0
            while 1:
                try:
                    png = fetch_png(bookid, elm)
                    Path(filename).write_bytes(png)
                    break
                except Exception as exc:
                    count += 1
                if count > 2:
                    break
            else:
                logger.warning(' Page {page} probbaly missing')
 
 
def main():  # pylint: disable=too-many-branches
    ''' main '''
    import os  # pylint: disable=unused-import
    import sys  # pylint: disable=unused-import
 
    bookid_str = ''
    yes_list = ['是', 'y', 'qui', '对', '好']
 
    logger.info(
        r'''
 
        访问 https://lib-nuanxin.wqxuetang.com/
        搜索点击感兴趣的书，例如 《计算机网络基础》
        https://lib-nuanxin.wqxuetang.com/#/Book/2175744
 
        网址尾部的数字2175744 即为书号 bookid。将bookid拷至
        系统剪贴板或记住该数字。
    '''
    )
 
    while 1:
        bookid_str = input('输入书号bookid：（例如 123, 退出输入 q 或 x） ')
 
        if any(map(lambda x: bookid_str.lower().startswith(x), ['q', 'x'])):
            break
 
        if not bookid_str.strip():
            continue
 
        try:
            bookid = int(bookid_str)
        except Exception as exc:
            logger.warning(f'nt 无效书号：{bookid_str}, 重新输入')
            continue
 
        if bookid < 1:
            logger.warning(f'nt 无效书号：{bookid_str}, 重新输入')
            continue
 
        count = 0
        success = False
        while 1:
            try:
                logger.info('ntt diggin...')
                info = bookinfo(bookid)
                success = True
                break
            except Exception as exc:
                logger.error(exc)
 
            count += 1
            if count > 3:
                logger.info('nt 事不过三，还是算了吧')
                break
 
            cont_or_not = input('再试一次？确认输入 y， 输入其他重输书号 ')
 
            if not cont_or_not.strip():
                continue
 
            if any(map(lambda x: cont_or_not.lower().startswith(x), yes_list)):
                continue
            else:
                break
 
        if not success:
            continue
 
        logger.info(bookinfo.jdata)
        logger.info(f'ntt 下载 {info}? ')
 
        yes_no = input('确认输入 y， 输入其他重输书号 ')
 
        if any(map(lambda x: yes_no.lower().startswith(x), yes_list)):
            logger.info(
                f'''
            开始下载 {info}...
            一般情况下（例如网络正常、服务器不太忙，IP未被限制）
            平均每100页约需15-20分钟)。
 
            终断（ctrl-C或ctrl-brea）程序后，已下载的页不会被覆盖。
            因此，如发现下载的页有问题或有些页未成功下载，可以删掉
            再用相同的 bookid 运行一次程序 python fetch_png.py
 
            '''
            )
            fetch_book(bookid)
 
    '''
    bookid = 3208943
    if not sys.argv[1:]:
        logger.info(' Provide at least a bookid.')
        logger.info(' Using %s to test ' % bookid)
    else:
        try:
            bookid = sys.argv[1]
        except Exception as exc:
            logger.warning(exc)
 
    page = 1
    if not sys.argv[2:]:
        logger.info(' Provide a page number.')
        logger.info(' Using %s to test ' % page)
    else:
        try:
            bookid = sys.argv[2]
        except Exception as exc:
            logger.warning(exc)
    logger.info(f' Fetchiing {bookid} {bookinfo(bookid)} page: {page}')
 
    res = fetch_png(bookid, page)
 
    filename = f'{bookid}-{page:03d}.png'
 
    count = 0
    while Path(filename).exists():
        count += 1
        filename = f'{bookid}-{page:03d}-{count}.png'
        if count > 4:
            break
    else:
        logger.warning(f' Possibly overwriting {filename}')
 
    Path(filename).write_bytes(res)
    logger.info(f'{filename} saved.')
 
    if sys.platform in ['win32']:
        os.startfile(f'{filename}')  # type: ignore
    # '''  # pylint: disable=pointless-string-statement
 
 
if __name__ == '__main__':
    main()

修正版更新：交互输入bookid。无引入人为延迟，一般情况下每100页需时15-20分钟。可能有些页显示“下载中”（由于未认为引入延迟，估计服务器有时忙不过来或是服务器有限流机制），可删去这些有问题的页再用系统bookid运行一次，程序会自动跳过已存在的页。