SQLException w/ Tomcat 7.0 JDBC connection pool and MySql

I'm trying to use the new Tomcat 7.0 JDBC connection pool and MySql. It says here that you can drop the latest tomcat-jdbc.jar into your tomcat/lib directory in a Tomcat 6.0 environment, and that's what I've done.

I'm using Spring to initialize and instantiate the DataSource per examples around the web:

<bean id="myDataSource" class="org.apache.tomcat.jdbc.pool.DataSource" destroy-method="close" 
p:driverClassName="${driver_class}"
p:url="${url}"
p:username="${username?root}"
p:password="${password}"
p:initialSize="10"
p:initSQL="SELECT DTS FROM DT_TM_TS FOR READ ONLY WITH UR"
p:minIdle="10"
p:maxIdle="100"
p:maxActive="100"
p:maxWait="6000"
p:jmxEnabled="true"
p:jdbcInterceptors="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer"
p:removeAbandoned="true"
p:removeAbandonedTimeout="60"
p:logAbandoned="true"
p:testOnBorrow="true"
p:testOnReturn="false"
p:testWhileIdle="false"
p:useEquals="false"
p:fairQueue="false"
p:timeBetweenEvictionRunsMillis="30000"
p:minEvictableIdleTimeMillis="30000"
p:validationInterval="1800000"
p:validationQuery="SELECT DTS FROM DT_TM_TS FOR READ ONLY WITH UR"
/>   

However when I try to connect to the db it throws this exception:

java.sql.SQLException: "com.mysql.jdbc.Driver"
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:243)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:176)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:647)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:589)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:452)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:130)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:99)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:110)
    at org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider.getConnection(InjectedDataSourceConnectionProvider.java:46)
    at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:111)
    at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2101)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1325)
    at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669)
    at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:132)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:225)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:308)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1477)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1417)
    at org.springframework.beans.factory.s开发者_C百科upport.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
    at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor.findDefaultEntityManagerFactory(PersistenceAnnotationBeanPostProcessor.java:529)
    at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor.findEntityManagerFactory(PersistenceAnnotationBeanPostProcessor.java:495)
    at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor$PersistenceElement.resolveEntityManager(PersistenceAnnotationBeanPostProcessor.java:656)
    at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor$PersistenceElement.getResourceToInject(PersistenceAnnotationBeanPostProcessor.java:629)
    at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:147)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:84)
    at org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor.postProcessPropertyValues(PersistenceAnnotationBeanPostProcessor.java:338)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1074)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
    at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:276)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:197)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:47)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4135)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4630)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
    at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
    at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:445)
    at org.apache.catalina.core.StandardService.start(StandardService.java:519)
    at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: java.lang.ClassNotFoundException: "com.mysql.jdbc.Driver"
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:247)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:236)
    ... 59 more

I've got mysql-connector-java-5.1.13-bin.jar in both the webapp WEB-INF/lib and tomcat/lib. I can connect fine specifying the driver details in persistence.xml (no DataSource/connection pooling).

There is actually a very simple workaround with Spring. Instead of having the Tomcat connection pool create the database connection and fail because of class loader shenanigans, let Spring create it and pass a reference to the connection pool.

<!-- Data source template for use in the connection pool. -->
<bean id="dataSourceTemplate" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="${jdbc.driver}" />
    <property name="url" value="${jdbc.url}" />
    <property name="username" value="${jdbc.username}" />
    <property name="password" value="${jdbc.password}" />
</bean>

<!-- Connection pool as data source. -->
<bean id="dataSource" class="org.apache.tomcat.jdbc.pool.DataSource" destroy-method="close">
    <!-- Refer to a separately created bean as a data source template to work around a quirk of Tomcat's class loader. -->
    <property name="dataSource" ref="dataSourceTemplate" />
    ...
</bean>

Then the connection pool will actually use the database connection as a template for creating as many additional connections as it needs.

The best part is that you don't have to mess with tomcat/lib, which you may not even have access to.

I'm using Spring 3.1, Hibernate 4.0, VMware vFabric tc Server Developer Edition 2.6.1 with Tomcat 7.0.20.B and Maven 3. Having the connector managed by Maven I encountered the same issue.

Infact reading the manual I've found

driverClassName

(String) The fully qualified Java class name of the JDBC driver to be used. The driver has to be accessible from the same classloader as tomcat-jdbc.jar

So I resolved by adding the mysql connector (mysql-connector-java-5.1.18-bin.jar) in the lib directory of Tomcat (vfabric-tc-server-developer-2.6.1.RELEASE/tomcat-7.0.20.B.RELEASE/lib) and setting in Maven the scope of the connector package to provided.

In Tomcat 6.0 I need to put my JDBC drivers into common/lib/ext

But the search path for that is configured in catalina.properties check out the property common.loader in there. Make sure that common/lib is listed there.