I can connect to my database with a simple classe Java like this :
package javappli;

import java.sql.*;

public class Main {

    public static void main(String[] args){

        String pilote = "com.mysql.jdbc.Driver";

        try{
            Class.forName(pilote);
            Connection connexion =
DriverManager.getConnection("jdbc:mysql://localhost/articles","root","root");
            connexion.setAutoCommit( true );
            Statement instruction = connexion.createStatement();
            ResultSet resultat = instruction.executeQuery("SELECT *
FROM articles");
            while(resultat.next()){

                System.out.println("code:
"+resultat.getString("code"));
                    System.out.println("nom:
"+resultat.getString("nom"));
                        System.out.println("Prix:
"+resultat.getFloat("prix"));
                            System.out.println("Stock actuel:
"+resultat.getInt("stockActuel"));
                                System.out.println("Stock minimum:
"+resultat.getInt("stockMinimum"));

            }
                    }
        catch (Exception e){

            System.out.println("driver failed : "+e);
        }
    }
}
In Another test, I create a datasource with Tomcat Admin in
Ressources->datasources like this:
JNDI Name: jdbc/test
Data Source URL:jdbc: mysql://localhost:3306/test?autoReconnect=true
JDBC Driver Class: com.mysql.jdbc.Driver
User Name: root
Password: root
Max. Active Connections: 4
Max. Idle Connections: 2
Max. Wait for Connection:5000

And modify a context.xml like this:

<Context path="/test">
 <ResourceLink name="jdbc/test"
               type="javax.sql.DataSource"
               global="jdbc/test"/>
 <Logger className="org.apache.catalina.logger.FileLogger"
prefix="test" suffix=".log" timestamp="true"/>

And the web.xml like this :

<resource-ref>
  <description>Connection pool</description>
  <res-ref-name>jdbc/test</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
  <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

But I doesn't work, if I try to execute an application with a simple
JSP.

If you have ideas, give me them
Thank

Kris