在我看来，addAttachment-Method总是替换当前的附件。
从PyPDF2 Github中的www.example.com：pdf.py in the PyPDF2 Github :

def addAttachment(self, fname, fdata):
    file_entry = DecodedStreamObject()
    file_entry.setData(fdata)
    file_entry.update({
            NameObject("/Type"): NameObject("/EmbeddedFile")
            })

    efEntry = DictionaryObject()
    efEntry.update({ NameObject("/F"):file_entry })

    filespec = DictionaryObject()
    filespec.update({
            NameObject("/Type"): NameObject("/Filespec"),
            NameObject("/F"): createStringObject(fname),  # Perhaps also try TextStringObject
            NameObject("/EF"): efEntry
            })

    embeddedFilesNamesDictionary = DictionaryObject()
    embeddedFilesNamesDictionary.update({
            NameObject("/Names"): ArrayObject([createStringObject(fname), filespec])
            })

    embeddedFilesDictionary = DictionaryObject()
    embeddedFilesDictionary.update({
            NameObject("/EmbeddedFiles"): embeddedFilesNamesDictionary
            })
    # Update the root
    self._root_object.update({
        NameObject("/Names"): embeddedFilesDictionary
        })

我相信

self._root_object.update({
        NameObject("/Names"): embeddedFilesDictionary
        })

替换附件，而不是添加附件。

• • EDIT：**这个脚本为我附加了两个. txt文件。它使用了上面的addAttachment方法，我稍微调整了一下，以允许附加多个文件。

from PyPDF2 import PdfFileReader, PdfFileWriter
from PyPDF2.generic import DecodedStreamObject, NameObject, DictionaryObject, createStringObject, ArrayObject

def appendAttachment(myPdfFileWriterObj, fname, fdata):
    # The entry for the file
    file_entry = DecodedStreamObject()
    file_entry.setData(fdata)
    file_entry.update({NameObject("/Type"): NameObject("/EmbeddedFile")})

    # The Filespec entry
    efEntry = DictionaryObject()
    efEntry.update({ NameObject("/F"):file_entry })

    filespec = DictionaryObject()
    filespec.update({NameObject("/Type"): NameObject("/Filespec"),NameObject("/F"): createStringObject(fname),NameObject("/EF"): efEntry})

    if "/Names" not in myPdfFileWriterObj._root_object.keys():
        # No files attached yet. Create the entry for the root, as it needs a reference to the Filespec
        embeddedFilesNamesDictionary = DictionaryObject()
        embeddedFilesNamesDictionary.update({NameObject("/Names"): ArrayObject([createStringObject(fname), filespec])})

        embeddedFilesDictionary = DictionaryObject()
        embeddedFilesDictionary.update({NameObject("/EmbeddedFiles"): embeddedFilesNamesDictionary})
        myPdfFileWriterObj._root_object.update({NameObject("/Names"): embeddedFilesDictionary})
    else:
        # There are files already attached. Append the new file.
        myPdfFileWriterObj._root_object["/Names"]["/EmbeddedFiles"]["/Names"].append(createStringObject(fname))
        myPdfFileWriterObj._root_object["/Names"]["/EmbeddedFiles"]["/Names"].append(filespec)

fr = PdfFileReader('dummy.pdf','rb')
fw = PdfFileWriter()
fw.appendPagesFromReader(fr)

my_attach_files = ['test.txt','test2.txt']
for my_test in my_attach_files:
    with open(my_test, 'rb') as my_test_attachment:
        my_test_data = my_test_attachment.read()
    appendAttachment(fw, my_test, my_test_data)

with open('dummy_new.pdf','wb') as file:
    fw.write(file)

希望这对你有用。

**免责声明：**我是borb的作者，此答案中使用的库

在borb中，Document类有一个方法add_embedded_file，它接受一个文件名（将显示在PDF查看器中）和字节。
此简短代码片段显示如何将嵌入文件添加到现有PDF：

from borb.pdf import Document
from borb.pdf import PDF

import typing

doc: typing.Optional[Document] = None
with open("input.pdf", "rb") as fh:
    doc = PDF.loads(fh)

# The next line adds an embedded file to the PDF.
# In order to keep this example short, I've used an inline byte string
# but you can of course read a file, and use those bytes
doc.add_embedded_file("name.json", b"{}")

# store
with open("output.pdf", "wb") as fh:
    PDF.dumps(fh, doc)