Int64 id = 0;

int tmp = (int)readInt();---------》Int64 tmp = (Int64)readInt();

id = id + tmp * 256 * 256 * 256 * 256;

--->如果tmp是int类型，那么tmp * 256 * 256 * 256 * 256==0

-->必须改为Int64 tmp，这样才能正确计算出非0的实际值

Debug.Log("Entity id " + id);