This gets repeated a lot. Maybe Chinese propaganda make this point to justify its outward investments to the Chinese people. Statements like this then take on a sinister sheen when discussed in the West.
Commodities are fungible and China is rich in natural resources itself. Oil is the one thing it is insecure about yet the insecurity is much more about a potential blockade in time of conflict than insufficiency of suppliers. Yes it has interests to see more supplies so it certainly would encourage investments in natural resources but to control the resources? That doesn't even make sense in the modern (WTO) context. It can't even control rare earth exports when 90% of the supply is based inside China, how can it expect to control supplies outside of China?
China has a high savings rate and runs a trade surplus and by necessity it will export capital. There is no other way around it. The Chinese government right now finds it more attractive investing in overseas infrastructures than buying more US Treasury bills.