ho questa servlet:
codice:
package operazioni_database;

import java.io.IOException;
import java.sql.*;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Insert extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html");
        String entrate = request.getParameter("txtEntrate".trim());
        String uscite = request.getParameter("txtUscite".trim());
        String causale = request.getParameter("txtCausale".trim());
//        String data = request.getParameter("data".trim());
        boolean proceed = false;
        try {
            if (entrate != null && uscite != null && causale != null /*&& data != null*/) {
                if (entrate.length() > 0 && uscite.length() > 0 && causale.length() > 0) {
                    proceed = true;
                    Connection conn = Connessione.getConnection();
                    PreparedStatement ps = null;
                    String sql = "INSERT INTO movimenti(entrate,uscite,causale,data) VALUES(?,?,?,curdate())";
                    ps = conn.prepareStatement(sql);
                    if (proceed) {
                        ps.setString(1, entrate);
                        ps.setString(2, uscite);
                        ps.setString(3, causale);
                        ps.executeUpdate();
                    }
                    RequestDispatcher disp = request.getRequestDispatcher("DoQuery");
                    disp.forward(request, response);
                    ps.close();
                }
            }
        } catch (ClassNotFoundException ex) {
            ex.getMessage();
        } catch (SQLException ex) {
            ex.getMessage();
        }
    }
}
in index.jsp ho il form:
codice:
.....
    <form action="Insert" method="post">
        <input type="text" name="txtEntrate" value="100"/>

        <input type="text" name="txtUscite" value="0"/>

        <input type="text" name="txtCausale" value="jsp 1"/>

        <!--<input type="text" name="txtData" />
-->
        <input type="submit" name="Submit" value="Submit" />
    </form>
quando do il submit:
HTTP method POST is not supported by this URL.

l'errore dipende dal server (tomcat) o da java??