title: Could not open Hibernate Session for transaction
body: <p>I am getting this error. please help me.</p>
  
  <pre>org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Cannot open connection
   org.springframework.orm.hibernate3.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:599)
   org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:374)
   org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:263)
   org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:101)
   org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
   $Proxy20.findFlierByID(Unknown Source)
   servlets.AwardServlet.doGet(AwardServlet.java:34)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
  root cause
  
  org.hibernate.exception.GenericJDBCException: Cannot open connection
   org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:126)
   org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:114)
   org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
   org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
   org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
   org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
   org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142)
   org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85)
   org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1354)
   org.springframework.orm.hibernate3.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:558)
   org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:374)
   org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:263)
   org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:101)
   org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
   $Proxy20.findFlierByID(Unknown Source)
   servlets.AwardServlet.doGet(AwardServlet.java:34)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
  root cause
  
  org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
   org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1452)
   org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
   org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
   org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.getConnection(LocalDataSourceConnectionProvider.java:82)
   org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
   org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
   org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142)
   org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85)
   org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1354)
   org.springframework.orm.hibernate3.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:558)
   org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:374)
   org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:263)
   org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:101)
   org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
   $Proxy20.findFlierByID(Unknown Source)
   servlets.AwardServlet.doGet(AwardServlet.java:34)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
  root cause
  
  java.lang.NullPointerException
   sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(Unknown Source)
   sun.jdbc.odbc.JdbcOdbcDriver.knownURL(Unknown Source)
   sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(Unknown Source)
   java.sql.DriverManager.getDriver(Unknown Source)
   org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1437)
   org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
   org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
   org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.getConnection(LocalDataSourceConnectionProvider.java:82)
   org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446)
   org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
   org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142)
   org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:85)
   org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1354)
   org.springframework.orm.hibernate3.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:558)
   org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:374)
   org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:263)
   org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:101)
   org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
   $Proxy20.findFlierByID(Unknown Source)
   servlets.AwardServlet.doGet(AwardServlet.java:34)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
   javax.servlet.http.HttpServlet.service(HttpServlet.java:717)</pre>
  
  <p>I have seen many examples on net but i could'nt solve  this problem. so please help me.</p>