I can feel you on that one, having experienced similar problems during my undergraduate studies. It is true that it is very difficult to find a true friend among Chinese classmates. There seems always to be a huge barrier among us and them. As a group of foreigners in that promotion, we tried to integrate, by taking part in sports teams organized by the department, where we were welcome because of what we were able to bring on the table, inviting classmates to attend birthdays or other events in the foreigners' dorms etc. but the gap was still there, so in our junior and senior years we basically gave up. The most frustrating was the feeling that because you were a foreigner you were not REALLY a member of the promotion. Parties organized were mostly discussed in students dorms, while foreigners were at their own dormitory, and in most of cases we learnt about those events only the following week.
Other minor things didn't help. For example, in the first two years foreigners were not allowed to take the political classes, which is good, but when calculating the means of the students these were taken into accounts, all the foreigners got 0 for not taking classes meaning that your good grades in other subjects (maths, business english, accounting in my case) were useless and foreigners were automatically at the bottom of the rankings. I really failed to see the logic behind this but since I didn't fail any subject and passed to the next year so it was fine.
For male students what might help is if you got hooked up with a girl in the class, and if that girl is strong enough to not take care of other classmates comments...
I have also found out that it is easier to get help if in return your classmates can gain something from you (help in English-related courses, invitation to foreigners parties with possible introduction to potential American/European bf/gf etc.). At the end of the time the more you give the more you receive, don't expect your Chinese classmates come to you if you don't make the first steps. That's true in most cases.
To be fair in my case at the beginning I received nice help from a girl from Harbin, but with time it seems she was singled out as being my gf, which was not the case, so rapidly she kind of backed off and I did understand that. Also some teachers were very helpful when help was requested from them. I had a friend, a girl from Angola at another department, who was so friendly with her teachers than most of them did not hesitate to help her out with her assignments during week-ends even coming to her dorm sometimes.
Nevertheless with years passing by my classmates became more mature and the relations were more relax by the time of graduation. Now several years after finishing my courses I am still in touch with some of them (mostly girls though

) although during the years of study we didn't have much in common.
I believe most of the problems come from the inexperience of classmates and even the departments in dealing with foreigners, the age difference sometimes (most of the African are a couple of years older than the 16-1yrs old freshmen who enter Chinese universities), the separation that seems to exist between foreigners and Chinese (different dorms, different rules, courses to be taken by one group and not by the other, political activities at the university level which the foreigners obviously are not permitted to attend etc.), the lack of flexibility, the group dominance over individual thinking as it is often the case in China, different educational backgrounds etc.