public class StartServlet extends DispatcherServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        if (req.getParameter("add") != null) super.forward("/addPage.jsp", req, resp);
        else if (req.getParameter("last") != null) super.forward("/view", req, resp);
    }
}

ID: <input type="text" name="id"><br/>
Data: <input type="text" name="data"><br/>
<input type="submit" name="add" value="Добавить">

public class DataBaseAddServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        DatabaseManager dbManager = new DatabaseManager();
        String id = req.getParameter("id");
        String data = req.getParameter("data");
        dbManager.addDocument(id, data); //в этой функции добавляется текущее время, преобразуется в JSON и добавляется в БД
    }
}

ID: <input type="text" name="id"><br/>
Data: <input type="text" name="data"><br/>

<input type="submit" name="add" value="Добавить">

String id = req.getParameter("id");
String data = req.getParameter("data");
dbManager.addDocument(id, data);

<form action="add" method="POST">
...