Unless you are in transit, arriving late and have a flight that departs the following day, you would not be able to spend the night at San Jose International Airport
San Jose Operations
No person shall sleep in or remain in the Airport terminals overnight for the purpose of lodging, unless: (a) the person has arrived at, is in transit through, or will be departing from the Airport as an airline passenger within twenty-four (24) hours, as evidenced by a valid travel itinerary, ticket, or boarding pass matching the person’s valid identification; or (b) the person is awaiting the arrival of a travel passenger due to arrive within two (2) hours, or within four (4) hours if the passenger’s travel has been delayed, as evidenced by verifiable travel information
The period each day between the hours of 11 p.m. and 4 a.m., or in the International Arrivals Facility from one hour after the last international flight using that facility to one hour before the first international flight of the day using that Facility.
Safety is under the purview of a special unit of the San Jose Police Department, the Airport Division whom you might just meet should you decide to spend the night at SJC.