Java Hibernate Web应用程序无法使用MySQL数据库显示数据

Question

I am learning Java CRUD operation with Hibernate . I am using MYSQL database for back end and its running without any problem . But when i run the application ,its shows following errors .

java.lang.ExceptionInInitializerError
    at com.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:36)
    at com.util.HibernateUtil.getSessionFactory(HibernateUtil.java:42)
    at com.dao.UserDAO.AllUsers(UserDAO.java:26)
    at com.controller.bean.UserBean.getUsers(UserBean.java:38)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:363)
    at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:140)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:204)
    at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:226)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
    at javax.faces.component.UIData.getValue(UIData.java:732)
    at org.primefaces.component.datatable.DataTable.getValue(DataTable.java:1002)
    at org.primefaces.component.api.UIData.getDataModel(UIData.java:629)
    at javax.faces.component.UIData.getRowCount(UIData.java:356)
    at org.primefaces.component.api.UIData.calculateFirst(UIData.java:175)
    at org.primefaces.component.datatable.DataTableRenderer.preRender(DataTableRenderer.java:110)
    at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:82)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:919)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
    at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
    at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:456)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:133)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282)
    at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235)
    at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.hibernate.boot.registry.classloading.spi.ClassLoadingException: Unable to load class [com.mysql.jdbc.Driver]
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:245)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.loadDriverIfPossible(DriverManagerConnectionProviderImpl.java:200)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.buildCreator(DriverManagerConnectionProviderImpl.java:156)
    at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.configure(DriverManagerConnectionProviderImpl.java:95)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:89)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.buildJdbcConnectionAccess(JdbcServicesImpl.java:260)
    at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:94)
    at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:89)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:206)
    at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:178)
    at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1885)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1843)
    at com.util.HibernateUtil.buildSessionFactory(HibernateUtil.java:29)
    ... 64 more
Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.mysql.jdbc.Driver
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl$AggregatedClassLoader.findClass(ClassLoaderServiceImpl.java:230)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at org.hibernate.boot.registry.classloading.internal.ClassLoaderServiceImpl.classForName(ClassLoaderServiceImpl.java:242)

Here is code UserBeans ..

ManagedBean(name = "userBean")
@ViewScoped
public class UserBean implements Serializable {
    private List<User> usersList;
    private List<User> searchList;
    private List<User> searchByRecordNoList;
    UserDAO userDao = new UserDAO();
    User user = new User();
    User newuser = new User();



        public List<User> getUsers()
    {

       usersList = userDao.AllUsers();
       int count =  usersList.size();
       return usersList;

    } 
    public void addUser(){

        String Remark = newuser.getRemark();
                Integer userId=0;
         userId= userDao.getId();
                newuser.setId(userId);
                  String Id = Integer.toString(newuser.getId());

                newuser.setRecordNo(Integer.toString(userId));
                userDao.add(newuser);

        System.out.println("User successfully saved.");
                  FacesMessage message= new FacesMessage(FacesMessage.SEVERITY_INFO, "Save Information","User successfully saved.");
                RequestContext.getCurrentInstance().showMessageInDialog(message);

                newuser = new User();
    }

        public void changeUser(User user) {
        this.user= user;


    }

        public void UpdateUser(User user){

        String Name = user.getName();
                 FacesMessage message1= new FacesMessage(FacesMessage.SEVERITY_INFO, "Name",Name);
                RequestContext.getCurrentInstance().showMessageInDialog(message1);
        userDao.update(user);
        System.out.println("User Info successfully saved.");
                  FacesMessage message= new FacesMessage(FacesMessage.SEVERITY_INFO, "Save Information","User updated successfully .");
                RequestContext.getCurrentInstance().showMessageInDialog(message);
                user = new User();

    }

        public void deleteUser(User user){
          String Name = user.getName();
          //FacesMessage message3= new FacesMessage(FacesMessage.SEVERITY_INFO, "Delete Item",contactName);

        // RequestContext.getCurrentInstance().showMessageInDialog(message3);
         userDao.delete(user);
          FacesMessage message= new FacesMessage(FacesMessage.SEVERITY_INFO, "Delete","Record deleted successfully");

         RequestContext.getCurrentInstance().showMessageInDialog(message);

    }
        public void searchbyRecordno(){

       searchByRecordNoList=userDao.SearchByRecordNo(user.getRecordNo());

         int count = searchByRecordNoList.size();
         FacesMessage message = new FacesMessage(FacesMessage.SEVERITY_INFO, "Number of Record Selected:", Integer.toString(count));
         RequestContext.getCurrentInstance().showMessageInDialog(message);

     }


    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

     public User getNewuser() {
        return newuser;
    }

    public void setNewuser(User newuser) {
        this.newuser = newuser;
    }



      public List<User> getUsersList() {
        return usersList;
    }

    public void setUsersList(List<User> usersList) {
        this.usersList = usersList;
    }

    public List<User> getSearchList() {
        return searchList;
    }

    public void setSearchList(List<User> searchList) {
        this.searchList = searchList;
    }

    public List<User> getSearchByRecordNoList() {
        return searchByRecordNoList;
    }

    public void setSearchByRecordNoList(List<User> searchByRecordNoList) {
        this.searchByRecordNoList = searchByRecordNoList;
    }

     public void onRowEdit(RowEditEvent event) {
        FacesMessage msg = new FacesMessage(" Edited Record No", ((User) event.getObject()).getRecordNo());
        FacesContext.getCurrentInstance().addMessage(null, msg);
        User editeduser = (User) event.getObject();
        userDao.update(editeduser);
    }



    public void onCancel(RowEditEvent event) {  
        FacesMessage msg = new FacesMessage("Edit Cancelled");   
        FacesContext.getCurrentInstance().addMessage(null, msg); 
        usersList.remove((User) event.getObject());
    }  


} 

Here is the code in UserDAO..

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.dao;

import java.util.List;
import java.util.ArrayList;
import org.hibernate.Query;
import org.hibernate.Session;
import com.util.HibernateUtil;
import com.model.pojo.User;


public class UserDAO {

    private User user;
    private User newuser;
    private List<User> DaoAllUsers;
    private List<User> DaoSearchUserList;
     //Session session;


    public List<User> AllUsers(){
        Session session = HibernateUtil.getSessionFactory().openSession();

        try{

               session.beginTransaction();
              DaoAllUsers = session.createCriteria(User.class).list();
               int count =DaoAllUsers.size();
             // FacesMessage message1 = new FacesMessage(FacesMessage.SEVERITY_INFO, "List Size", Integer.toString(count));//Debugging Purpose
       //RequestContext.getCurrentInstance().showMessageInDialog(message1);
               session.getTransaction().commit();
        }
        catch(Exception e){
          e.printStackTrace();
          session.getTransaction().rollback();
        }
            session.close();

        return DaoAllUsers;
    }

    public Integer getId (){
          Session  session = HibernateUtil.getSessionFactory().openSession();
        String hql = "select max(U.id) from Users U";
        Query query = session.createQuery(hql);
        List<Integer> results = query.list();
        Integer userId = 1;
                if (results.get(0) != null ) {
               userId = results.get(0)+1 ;
                }
                session.flush();

                 session.close();
                return userId;
    }

        public  List<User> SearchByRecordNo(String RecordNo) {

      Session session= HibernateUtil.getSessionFactory().openSession();
      List<User>   daoSearchList = new ArrayList<>();

        try{

              session.beginTransaction();
              Query qu = session.createQuery("From Users U where U.recordNo =:recordNo");//User is the entity not the table

              qu.setParameter("recordNo", RecordNo);
              daoSearchList=qu.list();
             int count = daoSearchList.size();
             session.getTransaction().commit();

        }
        catch(Exception e){
          e.printStackTrace();
         session.getTransaction().rollback();

        }
       finally {

          session.close();
        }  
        return daoSearchList;

}


    public void add(User newuser){
      Session session = HibernateUtil.getSessionFactory().openSession();
        try{
           String Id = Integer.toString(newuser.getId());
           // begin a transaction
             session.beginTransaction();
             session.merge(newuser);
              session.flush();
              System.out.println("NewUser saved, id: " +
newuser.getId());
              session.getTransaction().commit();


        }
        catch(Exception e){
          e.printStackTrace();
         session.getTransaction().rollback();
        }
           session.close();



    }

    public void delete(User user){
      Session session = HibernateUtil.getSessionFactory().openSession();
        try{
     String  name= user.getName();

               session.beginTransaction();
              session.delete(user);
               session.getTransaction().commit();
        }
        catch(Exception e){
          e.printStackTrace();
          session.getTransaction().rollback();
        }

            session.close();


    }

    public void update(User user){
      Session  session = HibernateUtil.getSessionFactory().openSession();
        try{

              session.beginTransaction();
             session.update(user);
             session.flush();

               session.getTransaction().commit();

        }
        catch(Exception e){
          e.printStackTrace();
          session.getTransaction().rollback();
        }
            session.close();
    }
} 

Here is the code in User Class.

@Entity
@Table(name="users"
    ,catalog="userinformation"
)
public class User  implements java.io.Serializable {

     private Integer id;
     private String recordNo;
     private String name;
     private Integer age;
     private String sex;
     private Date dob;
     private String remark;

    public User() {
    }

    public User(String recordNo, String name, Integer age, String sex, Date dob, String remark) {
       this.recordNo = recordNo;
       this.name = name;
       this.age = age;
       this.sex = sex;
       this.dob = dob;
       this.remark = remark;
    }

     @Id @GeneratedValue(strategy=IDENTITY)


    @Column(name="id", unique=true, nullable=false)
    public Integer getId() {
        return this.id;
    }

    public void setId(Integer id) {
        this.id = id;
    }


    @Column(name="RecordNo", length=20)
    public String getRecordNo() {
        return this.recordNo;
    }

    public void setRecordNo(String recordNo) {
        this.recordNo = recordNo;
    }


    @Column(name="Name", length=50)
    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }


    @Column(name="Age")
    public Integer getAge() {
        return this.age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }


    @Column(name="Sex", length=20)
    public String getSex() {
        return this.sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Temporal(TemporalType.DATE)
    @Column(name="Dob", length=10)
    public Date getDob() {
        return this.dob;
    }

    public void setDob(Date dob) {
        this.dob = dob;
    }


    @Column(name="Remark", length=50)
    public String getRemark() {
        return this.remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }


    //This method writes the values of contact object with System.out.println(Emp.toString()) code
    @Override
    public String toString() {
    return "users"
    + "\n\t RecordNo: " + this.recordNo   
    + "\n\t EmployeeName: " + this.name        
    + "\n\t Age: " + this.age
    + "\n\t Sex: " + this.sex
    + "\n\t Date of Birth: " + this.dob
    + "\n\t Remark: " + this.remark;
    }




}

Here is the code HibernateUtil Class .

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.util;


import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;



    public class HibernateUtil {
        //Annotation based configuration
    private static SessionFactory sessionFactory;
        private static SessionFactory buildSessionFactory() {
        try {
            // Create the SessionFactory from hibernate.cfg.xml
            Configuration configuration = new Configuration();
            configuration.configure("/hibernate.cfg.xml");
            System.out.println("Hibernate Annotation Configuration loaded");

            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
            System.out.println("Hibernate Annotation serviceRegistry created");

             sessionFactory = configuration.buildSessionFactory(serviceRegistry);

            return sessionFactory;
        }
        catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }


    public static SessionFactory getSessionFactory() {
        if(sessionFactory == null) sessionFactory = buildSessionFactory();
        return sessionFactory;
    }

    public static void shutdown() {
// Close caches and connection pools
       sessionFactory.close();
}



}

Here is the hibernate.cfg.xml file .

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/userinformation?zeroDateTimeBehavior=convertToNull</property>
    <property name="hibernate.connection.username">root</property>
   <property name="hibernate.connection.password"/>
    <property name="hibernate.connection.pool_size">10</property>
    <property name="show_sql">true</property>
    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.hbm2ddl.auto">update</property>
    <mapping class="com.model.pojo.User"/>
    <mapping class="com.model.pojo.User"/>
  </session-factory>

</hibernate-configuration>

Here is the code in hibernate.revenge.xml file ..

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-reverse-engineering PUBLIC "-//Hibernate/Hibernate Reverse Engineering DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd">
<hibernate-reverse-engineering>
  <schema-selection match-catalog="userinformation"/>
  <table-filter match-name="users"/>
</hibernate-reverse-engineering>

Here is the HTML Code .

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:p="http://primefaces.org/ui">



        <h:head>

            <h2><center>All User Information</center></h2>
        </h:head>

        <h:body>
            <h:form>

           <p:commandButton action="Search?faces-redirect=true" icon="ui-icon-search"  value="Search" />

    </h:form>


            <p:spacer>    </p:spacer>     
            <h:form id="form1">

                <p:dataTable  id="dataTable" var="user" paginator="true" rows="5" value="#{userBean.users}">
                    <p:column headerText="RecordNo">
                        <h:outputText value="#{user.recordNo}"/>

                    </p:column>
                    <p:column headerText="Name" >
                        <h:outputText value="#{user.name}"/>

                    </p:column>
                    <p:column sortBy="#{user.age}" headerText="Age" >
                        <h:outputText value="#{user.age}"/>

                    </p:column>

                    <p:column headerText="Sex">
                        <h:outputText value="#{user.sex}"/>
                    </p:column>
                    <p:column headerText="Date of Birth" >
                     <h:outputText value="#{user.dob}">
                     <f:convertDateTime type="date" pattern="dd-MMM-yyyy"/>
                         </h:outputText>
                   </p:column>


                    <p:column headerText="Remark" >
                        <h:outputText value="#{user.remark}"/>
                    </p:column>


                </p:dataTable>   

                 </h:form>  


            <h:panelGroup >

            <h3>Add User Information</h3>
            <h:form>
                <p>User Name: <p:inputText value="#{userBean.newuser.name}" /></p>
                <p>User Age: <p:inputText value="#{userBean.newuser.age}" />Enter Number Only</p>
                 <h:panelGrid    columns="2" style="margin-bottom:10px" cellpadding="5">
                   <p>Choose Sex:</p>
                   <p:selectOneMenu label="Sex:" value="#{userBean.newuser.sex}" id="ulist2">
                        <f:selectItem itemLabel="Select One" itemValue="" />
                        <f:selectItem itemLabel="Male" itemValue="Male"/>
                        <f:selectItem itemLabel="Female" itemValue="Female"/>

                </p:selectOneMenu>
        </h:panelGrid>
               <p>User Date of Birth: <p:calendar id="dop" value="#{userBean.newuser.dob}" label="DatePosted:"

required="true" pattern="dd/MMM/yyyy" effect="slideDown" requiredMessage="Please Enter Date of Posting!"

navigator="true" showButtonPanel="true" yearRange="c-60:c+60" /> </p>




                <p>Remark: <p:inputTextarea value="#{userBean.newuser.remark}" /></p>

                <p><p:commandButton icon="ui-icon-plusthick" update=":form1:dataTable"  type="submit" value="add" action="#{userBean.addUser()}" /></p>
                </h:form>

        </h:panelGroup>



        </h:body>

    </html>

Here is the screen shot when i run the application .

Answer 1

Looks like the MySQL driver can't be found. Some things to check:

• Has the driver JAR been deployed to the serverlet container or application server?
• Have the connection details been verified through the container console?