Erreur de connexion

package newpackage;


import java.io.IOException;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Vector;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**


* Servlet implementation class AjouterClient

*/
@WebServlet("/AjouterClient")
public class AjouterClient extends HttpServlet {
 private static final long serialVersionUID = 1L;
    private String Driver;
 
 

    /**


* @see HttpServlet#HttpServlet()

*/
    public AjouterClient() {
        super();
    }    
    protected void connexionBdd(){
            try {
                Class.forName(Driver);
            } catch (ClassNotFoundException ex) {
                Logger.getLogger(AjouterClient.class.getName()).log(Level.SEVERE, null, ex);
            }
  try{
            Class.forName("org.postgresql.Driver");
            System.out.println("Driver chargé");
            
            
        }catch(Exception e){
            System.out.println("Driver non chargé"+e.getMessage());
        }

//Connexion à la Base de données

try{
            String url = "jdbc:postgresql://localhost:5432/Banque";
      String user = "postgres";
      String passwd = "postgres";

      Connection conn = DriverManager.getConnection(url, user, passwd);
      System.out.println("Connexion effective !");         

     }catch(Exception e){
            System.out.println("Base de données non connectée"+e.getMessage());
        }
    }
 public void setData(String s) {
            state.executeUpdate(s);
          

 }
    
    
        @Override
 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  // TODO Auto-generated method stub
  response.getWriter().append("Served at: ").append(request.getContextPath());
 }

 /**


* @param request

* @param response

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/
 protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  String nom = request.getParameter("nom");
  String prenom = request.getParameter("prenom");
  Double solde = Double.parseDouble(request.getParameter("solde"));
  String requete ="INSERT INTO CLIENT(nom,prenom,solde) VALUES('"+nom+"','"+prenom+"',"+solde+");";
  System.out.println(requete);
  connexionBdd();
  setData(requete);
  doGet(request, response);
  response.sendRedirect("index.jsp");
 }

    private static class state {

        private static void executeUpdate(String s) {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }

        public state() {
        }
    }

}