Short:
You are extremely unlikely to have any problems at all if you are otherwise sensibly behaved. If you did happen to incur the wrath of the authorities I would not be overly surprised if a statute relating to knife carrying was found to have been breached. It's not something I'd be concerned about personally, see below.
You hear about some very very very bad things happening in China. More than a few of these are probably true. If you do run afoul of the system things can go rather wrong. But, they do generally treat foreigners well enough officially. (I have seen a 'local' man with his hands handcuffed behind him pushed to the ground on a city street by a largish group of um - guys with all the same colour clothes and helmets and matching sticks... and kicked repeatedly in the back. Why I know not. He didn't actually seem to care too much, to my surprise.) Whereas I have given people in authority enough excuse to justify treating me badly and they have instead treated me acceptably well. YMMV.
My knives are absolutely NOT intended as weapons. When occasion arises I instruct young people what to do with a knife if you are attacked - viz: "Bury it deep in your pocket and make sure nobody knows that you have it - odds are that any one who wishes you physical harm knows how to use a knife better than you do, will probably manage to take it from you and giving them something that may be more liable to kill you than what they have already is probably unwise." But - other people do not know why I carry them.
The two knives I usually carry are metal, folding, single blade. About 3" I think. Neither is spring open-open style but both can be seen as borderline 'flick knife' as both are designed to be opened one handed either by a stud on the blade on one which allows the thumb to swing the blade or by pressure on a short behind the hinge blade extension on the other which allows thumb pressure to rotate the blade. Both lock open and have a latch that must be operated to allow them to close. Again one handed with due practice. I practiced with both enough to allow me to withdraw the knife and open it in one motion and to also put it away one handed.
ie the knives are of a type that while useful would be expected to be borderline legal or worse in some countries. They are sharp and pointed and made to be opened as they are taken from a pocket. The blades lock open.
I once - stupidly - failed to place a Swiss Army knife and it was found in my bag at boarding security at an inland (non-border) Chinese airport airport and confiscated. I had no problem at all with that at it was a clear rule violation on my part. They also however confiscated an inkjet cartridge refiller that had 3 x 10mm needles internal to it. It had previously passed through several international customs checks and several internal Chinese customs checks. I was so annoyed at the complete ludicrousness of the decision and their failure to accept my explanation re prior acceptability that I yelled loudly at the 'customs' man - the only time I've ever done so and an immensely stupid thing to do (and very out of character for me.) He politely stood his ground and I continued to my aircraft. I have no doubt that he would have been within his rights to decide to teach me a lesson and delay my trip while I was subject to more intensive official processes. My point in detailing that occurrence (apart from showing how stupid I can be on (rare :-) ) occasions) is to show that even when I did "try" to carry a knife onto an aircraft and then behaved in a manner which everyone knows may result in 'a delay in your journey', they still behaved politely and properly and ignored my behaviour.
More soonSo ................
Knives are openly available in many places in China.
Knives carried in checked baggage do not seem to excite them.
Knife carrying noisy idiots at check in may be tolerated.
All the same, don't push your luck too far :-).
