Python使用PyPDF2为Pdf文件添加水印

import os,sys,shutil
import json
import glob
from pathlib import Path
import PyPDF2


pdfWriter = PyPDF2.PdfWriter()   
fi_path = 'file/309118'    
#读取水印文件第一页
water = PyPDF2.PdfReader('data/气虚质.pdf').pages[0]
fls = glob.glob(f'{fi_path}/*.pdf')
for fn in fls:
    #读取待添加水印文件
    reader = PyPDF2.PdfReader(fn)
    #待写入水印文件
    writer = PyPDF2.PdfWriter()
    #获取文件页数
    num = len(reader.pages)
    fi_name =Path(fn).stem.split('-')[0]
    code = int(fi_name)
    for i in range(num):
        page = reader.pages[i]
        if i == num -1:
            page.merge_page(water)
        writer.add_page(page)
    with open(f'{Path(fn).stem}.pdf', 'wb') as target_file:
        writer.write(target_file)
    print(Path(fn).stem,num,type(page))