Can I use the visa when I arrive in Beijing and leave the port of tianjin?

I leave Italy on October 4, I will stop at Abu Dhabi and my plane will arrive in BJ on October 5th.
I will be there two days because on October 7th I will take a Cruise ship departing from Tianjin and heading to Japan, Taiwan, Hong Kong and Singapore.
From Singapore I will take another plane to Italy.
What do you advise me to do?