在java servlet上保存列表

In the application I'm building using Java servlets, I have to be able to save a list of objects that contain information about some terminals (phone mobiles) that sent http requests to the servlet. I first thought using a static Vector which I will be creating only once, the first time someone calls the servlet. The problem is, I always find myself in the situation where the Vector object contains only one element, namely the last terminal that called the servlet. The problem is, I don't even know if this is the way to do it or if there's another approach to it. Can you please make some light?In the application I'm building using Java serv