HibernateUtil.java

public static void connessione(){
       
       
        Session session = HibernateUtil.currentSession();
       
       
        Transaction tx= session.beginTransaction();
               
        Cat princess = new Cat();
        princess.setName("Princess");
        princess.setSex('F');
        princess.setWeight(7.4f);
               
        session.save(princess);
               
        tx.commit();
       
        HibernateUtil.closeSession();
       
    }

org.hibernate.exception.GenericJDBCException: Cannot open connection
   org.hibernate.exception.ErrorCodeConverter.handledNonSpecificException(ErrorCodeConverter.java:92)
   org.hibernate.exception.ErrorCodeConverter.convert(ErrorCodeConverter.java:80)
   org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
   org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
   org.hibernate.jdbc.AbstractBatcher.openConnection(AbstractBatcher.java:427)
   org.hibernate.jdbc.JDBCContext.connect(JDBCContext.java:168)
   org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:103)
   org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:49)
   org.hibernate.transaction.JDBCTransactionFactory.beginTransaction(JDBCTransactionFactory.java:24)
   org.hibernate.jdbc.JDBCContext.beginTransaction(JDBCContext.java:231)
   org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1073)
   org.hibernate.examples.quickstart.HibernateUtil.connessione(HibernateUtil.java:63)
   prova.processRequest(prova.java:56)
   prova.doGet(prova.java:72)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
   org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:362)

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

    <session-factory>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="connection.datasource">java:comp/env/jdbc/quickstart2</property>
        <property name="show_sql">false</property>
       
        <!-- Mapping files -->
        <mapping resource="org/hibernate/examples/quickstart/Cat.hbm.xml"/>

    </session-factory>

</hibernate-configuration>

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/quickstart2">
  <Logger className="org.apache.catalina.logger.FileLogger" prefix="quickstart2." suffix=".log" timestamp="true"/>
 
  <ResourceLink name="java:comp/env/jdbc/quickstart2" global="java:comp/env/jdbc/quickstart2"
      type="javax.sql.DataSource"/>
</Context>

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class name="org.hibernate.examples.quickstart.Cat" table="CAT">

        <!-- A 32 hex character is our surrogate key. It's automatically
            generated by Hibernate with the UUID pattern. -->
        <id name="id" type="string" unsaved-value="null" >
            <column name="CAT_ID" sql-type="char(32)" not-null="true"/>
            <generator class="uuid.hex"/>
        </id>

        <!-- A cat has to have a name, but it shouldn' be too long. -->
        <property name="name">
            <column name="NAME" length="16" not-null="true"/>
        </property>

        <property name="sex"/>

        <property name="weight"/>

    </class>

</hibernate-mapping>

<Context path="/quickstart2" docBase="quickstart2">
           <Resource name="jdbc/quickstart2" scope="Shareable" type="javax.sql.DataSource"/>
           <ResourceParams name="jdbc/quickstart2">
               <parameter>
                   <name>factory</name>
                   <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
               </parameter>
      
               <!-- DBCP database connection settings -->
               <parameter>
                   <name>url</name>
                   <value>jdbc:mysql://localhost:3306/quickstart2</value>
               </parameter>
               <parameter>
                   <name>driverClassName</name><value>com.mysql.jdbc.Driver</value>
               </parameter>
               <parameter>
                   <name>username</name>
                   <value>root</value>
               </parameter>
               <parameter>
                   <name>password</name>
                   <value>mox601</value>
               </parameter>
      
               <!-- DBCP connection pooling options -->
               <parameter>
                   <name>maxWait</name>
                   <value>3000</value>
               </parameter>
               <parameter>
                   <name>maxIdle</name>
                   <value>100</value>
               </parameter>
               <parameter>
                   <name>maxActive</name>
                   <value>10</value>
               </parameter>
           </ResourceParams>
   </Context>