We learn a technique or framework, it should first figure out what it is and what the main role is? So we can have on the whole of what we've learned a general understanding, reduce strangeness, increase learning information and learning efficiency.
As we all know, web sites based on the HTTP protocol. If you use Java as a server-side development language, and assuming that no technical framework for you to develop server-side program, how do need?
For each request from the browser, the general process should be such that:
(1) the server accepts HTTP requests from the client
(2) parsing the server receives the HTTP request, parses the HTTP parameters and attributes associated
(3) executed on the server logic calculation associated with the request
(4) server binding results, rendering HTML content sent to the client ().
The above process contains some small differences stencil operations: (1), (2), (4). If each request to do so, it is bound to complicate the development, implementation and each person may be slightly different, is not easy to transfer when the code changed hands. Servlet is to solve these problems.
With the Servlet, the server generally needs to accomplish the above step (3), and since the normalized Servlet, so that the code is easy to develop, and transfer appreciated, this greatly simplifies the development JAVA.
Of course, not limited to the role of the Servlet, and Session, Cookie management.