Well chinese SAM development isen't results of some glory espionage actions but a handicaped country by industrial capacitys effors to create one of their own. It is was one would assume, a lenghty and propelmatic venture. The first SAM system for PLAN, the HQ-61 took decades to get operational and it was completely outdated to comparing systems even when the development started.
As time passed on chinese where able to obtain foreing SAM systems, the Aspide and Crotale which emerged as LY-60 and HQ-7 which both were availble (tough only the HQ-7 was adopted) before the HQ-61 was in full service. As you may quess the servicelife of HQ-61 was quite short.
In the 90's chinese were able to increase their SAM quantity with top-of-the noch russian systems which both (S-300 and Buk) were adopted in service as such and both influenced new chinese developments like HQ-9 and HQ-16.
Nonetheless, the technology has been absorbed and can now be domestically manufactured and improved upon. HQ-9 looks a bit like the Shtil or 5V55 with long body rail like fins, but then so are a number of missiles including the RIM-66. However the radar set of the HQ-9 looks closer to the MPQ-53 used in the PAC, and has a detection to kill capability all in one unit, unlike the S-300PMU1/2.
Now that's a huge leap in both radar technology and as well as the quality of it. A set like the MPQ-53 has multiple arrays in one panel. In order to do that, without interference from each other, the arrays must have ultra low sidelobs or sidelob cancellation, something the Russians themselves could not achieve with their own units until this decade. Hence the Russians never fielded similar all in one units.
Even the chinese crown jewl, the APAR radar is rumoured based on the soviet program which was continued by the Kvant NPO in ukraine where it was left after the dissolution of USSR.
This rumor has been blown completely out of the water. Ukraine has admitted that the Kvant was only shipped after 2004 for evaluation, and already at that time, the 052C were undergoing trials in the water. The Kvant is only a search radar, and lacks fire control capabilities.