The apk package can be decompressed directly with winrar. If apk is not encrypted, you can view and replace the decompressed files. Then, to package apk, you need to find digital signature tools and packaging tools on the Internet. Pack the file first, and then run the digital signature tool to re-sign, so that the new apk can be installed and run. Generally, there are many modifications of apk embedded advertising content on the Internet. You can also search apk modification tools and find many.