Hi , As per the servlet specs DoGet is not a must .If you do not want anyone to access the servlet via typing the URL in the address bar you could just implement the DoPost method and inb the Form method tag that would call this servlet mention it as "Post"
Traditionally there where distinct uses for GET, POST and other HTTP message types, but over time many have fallen into rare usage and GET and POST have often been treated as interchangeable.
Going back to their original intents, GET was designed to be used for 'repeatable' requests, commonly called 'idempotent'. If you browse a catalogue, all 'browse' operations would be expected to be repeatable.
POST operations would involve state changes and not designed for repeating. Logging in, purchasing, registering etc would be POST operations.
While both involve sending and receiving data over HTTP, there are subtle differences that can encourage the choice between ond message type and another.