On a cruise that calls into Shanghai for one day do I need any sort of visa

Your eligibility for 24 hour visa free transit is determined by your itinerary. If the ports of call, immediately before and after Shanghai are in different countries or eligible territories, for example:

Busan (South Korea) - Shanghai - Okinawa (Japan)

or

Hong Kong - Shanghai - Busan

Then, you will be eligible for 24 hour visa free transit and you don't need any kind of visa. Also, if you are eligible for this visa free transit option, you will be granted a temporary entry permit that will allow you to explore Shanghai on your own or with an organized tour. This will be your choice.

Anyway, if you have a port of call, immediately before or immediately after Shanghai in mainland China, you will not be eligible for this visa free transit option. Also, you will not be eligible for this option if your ports of call, immediately before and after are both in the same country, fore example:

Nagasaki (Japan) - Shanghai - Okinawa (Japan)

As you can see, just take a look at your itinerary and you will be able to determine your eligibility. Also, if you feel insecure, just ask here.