Hi , i have a symple jsp page :
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ page import="java.sql.*" %>
-
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" >
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Pagina 2 elenco</title>
</head>
<body>
<jsp:useBean id="db" scope="page" class="classi.Db" ></jsp:useBean>
<%
//db.connettiAlDatabase("localhost", "java_db"," root", "root");
Connection connect= db.get_connessione();
out.println(connect);
// Class.forName("com.mysql.jdbc.Driver") ; // Imposta la connessione al server e al database
// Connection connect = DriverManager.getConnection("jdbc:mysql://localhost/java_db","root","root");
String sql = "select * from utenti";
/* Statement stmt = connect.createStatement();
ResultSet rs = stmt.executeQuery(sql);
String r = "<div><h1>Elenco dati utenti</h1><table>";
rs.first(); // si porta all'inizio del resulset
String a1,a2;
do {
a1="<a href='modificaUtente.jsp?idutente="+rs.getInt("id")+"'>Mod</a>";
a2="<a href=\"elimina_utente.jsp?idutente="+rs.getInt("id")+"\"onclick=\"return confirm('Procedo con la cancellazione');\">Elimina</a>";
r += "<tr><td>" + rs.getString("nome") + "</td>";
r += "<td>" + rs.getString("cognome") + "</td>";
r += "<td>" +a1+"</td>";
r += "<td>" +a2+"</td></tr>";
//String nome = rs.getString("nome");
//String cognome = rs.getString("cognome");
//out.println("nome : " + nome);
//out.println("cognome : " + cognome);
}while(rs.next()); // scorre i record
r += "</table>";
out.print(r);
connect.close();
*/
%>
<a href="indexjsp">Torna a index</a>
</body>
</html>
and a class in the same project :
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package classi;
import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author Frame 11
*/
public class Db {
private Connection connect;
private int id;
private String prova;//per testare la stringa per connettersi
private String server, nomedb, username, password;
public Db(){
try {
try {
Class.forName("com.mysql.jdbc.Driver") ; // Imposta la connessione al server e al database
} catch (Exception e) {
throw new RuntimeException("Oops, failed to initialize the driver"); }
// prova="jdbc:mysql://"+server+"/"+nomedb+",\""+username+"\",\""+password+"\"";
connect = DriverManager.getConnection("jdbc:mysql://localhost/java_db","root","root");
} catch (SQLException ex) {
Logger.getLogger(Db.class.getName()).log(Level.SEVERE, null, ex);
}
}
public void connettiAlDatabase(String server,String nomeDb,String username,String password){
try {
try {
Class.forName("com.mysql.jdbc.Driver") ; // Imposta la connessione al server e al database
} catch (ClassNotFoundException ex) {
Logger.getLogger(Db.class.getName()).log(Level.SEVERE, null, ex);
}
// prova="jdbc:mysql://"+server+"/"+nomedb+",\""+username+"\",\""+password+"\"";
// Imposta la connessione al server e al database
connect = DriverManager.getConnection("jdbc:mysql://" + server + "/" + nomeDb +"?" + "user="+username+"&password="+password); // N.B. la password vuota si scrive password=
} catch (SQLException ex) {
Logger.getLogger(Db.class.getName()).log(Level.SEVERE, null, ex);
}
}
public Connection get_connessione(){
return connect;
}
public ResultSet getDati(Connection connect,String sql){
this.connect=connect;
Statement stmt;
ResultSet rs=null;
try {
stmt = connect.createStatement();
rs = stmt.executeQuery(sql);
} catch (SQLException ex) {
Logger.getLogger(Db.class.getName()).log(Level.SEVERE, null, ex);
}
return rs;
}
public void eliminazione(String id,String tabelladb){
try {
this.id=Integer.parseInt(id);
String nometabella=tabelladb;
String sql = "delete from "+nometabella+" where id="+id;
Statement stmt = connect.createStatement();
stmt.executeUpdate(sql);
} catch (SQLException ex) {
Logger.getLogger(Db.class.getName()).log(Level.SEVERE, null, ex);
}
}
/*
public String getProva(){
return prova;
}
*/
}
i have imported the external jar my-sql connector in the project but when i run it i have :
HTTP Status 500 -
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperException: java.lang.RuntimeException: Oops, failed to initialize the driver
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:534)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:457)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
root cause
java.lang.RuntimeException: Oops, failed to initialize the driver
classi.Db.<init>(Db.java:27)
org.apache.jsp.pagina2_jsp._jspService(pagina2_jsp.java:72)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.12 logs.
Apache Tomcat/7.0.12
] 
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